Network Working Group N.B. Sopher Internet-Draft O. Finkelman Obsoletes: 8007 (if approved) Qwilt Intended status: Standards Track S. Mishra Expires: 24 April 2025 Verizon J.K. Robertson Qwilt A. Arolovitch Viasat 21 October 2024 Content Delivery Network Interconnection (CDNI) Control Interface / Triggers 2nd Edition draft-ietf-cdni-ci-triggers-rfc8007bis-15 Abstract This document obsoletes RFC8007. The document describes the part of Content Delivery Network Interconnection (CDNI) Control interface that allows a CDN to trigger activity in an interconnected CDN that is configured to deliver content on its behalf. The upstream CDN MAY use this mechanism to request that the downstream CDN preposition metadata or content as well as request that it invalidate or purge metadata or content. The upstream CDN MAY monitor the status of activity that it has triggered in the downstream CDN. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 24 April 2025. Copyright Notice Copyright (c) 2024 IETF Trust and the persons identified as the document authors. All rights reserved. Sopher, et al. Expires 24 April 2025 [Page 1] Internet-Draft CDN Interconnect Triggers October 2024 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 2. Model for CDNI Triggers . . . . . . . . . . . . . . . . . . . 5 2.1. REST Architecture . . . . . . . . . . . . . . . . . . . . 5 2.2. HTTP Methods . . . . . . . . . . . . . . . . . . . . . . 6 2.3. Trigger . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.4. Trigger Collection . . . . . . . . . . . . . . . . . . . 7 2.5. Session Overview . . . . . . . . . . . . . . . . . . . . 7 2.6. Trigger Processing . . . . . . . . . . . . . . . . . . . 9 2.6.1. Timing and Order . . . . . . . . . . . . . . . . . . 9 2.6.2. Scope . . . . . . . . . . . . . . . . . . . . . . . . 9 2.6.3. Results . . . . . . . . . . . . . . . . . . . . . . . 10 2.7. Trigger Extensibility . . . . . . . . . . . . . . . . . . 10 2.8. Multiple Interconnected CDNs . . . . . . . . . . . . . . 11 3. CDNI Trigger Interface . . . . . . . . . . . . . . . . . . . 13 3.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 14 3.2. Modifying Triggers . . . . . . . . . . . . . . . . . . . 15 3.3. Cancelling Triggers . . . . . . . . . . . . . . . . . . . 16 3.4. Checking Status . . . . . . . . . . . . . . . . . . . . . 16 3.4.1. Polling Trigger Collections . . . . . . . . . . . . . 17 3.4.2. Polling Triggers . . . . . . . . . . . . . . . . . . 18 3.5. Deleting Triggers . . . . . . . . . . . . . . . . . . . . 18 3.6. Expiry of Triggers . . . . . . . . . . . . . . . . . . . 19 3.7. Loop Detection and Prevention . . . . . . . . . . . . . . 19 3.8. Error Handling . . . . . . . . . . . . . . . . . . . . . 19 3.8.1. Error Propagation . . . . . . . . . . . . . . . . . . 20 4. CI/T Object Properties and Encoding . . . . . . . . . . . . . 23 4.1. Trigger Resource . . . . . . . . . . . . . . . . . . . . 24 4.1.1. Trigger Action . . . . . . . . . . . . . . . . . . . 26 4.1.2. Trigger Specs . . . . . . . . . . . . . . . . . . . . 27 4.1.3. Trigger Extensions . . . . . . . . . . . . . . . . . 35 4.1.4. Trigger State . . . . . . . . . . . . . . . . . . . . 48 4.1.5. Trigger Errors . . . . . . . . . . . . . . . . . . . 49 4.2. Trigger Collection Resource . . . . . . . . . . . . . . . 54 4.2.1. Filtered Collections by Status Link . . . . . . . . . 56 4.2.2. Filtered Collections by Label Link . . . . . . . . . 57 4.3. Other CI/T Objects . . . . . . . . . . . . . . . . . . . 57 Sopher, et al. Expires 24 April 2025 [Page 2] Internet-Draft CDN Interconnect Triggers October 2024 4.3.1. URL Type . . . . . . . . . . . . . . . . . . . . . . 57 4.3.2. ObjectList . . . . . . . . . . . . . . . . . . . . . 58 4.3.3. CDN Provider ID . . . . . . . . . . . . . . . . . . . 64 5. Footprint and Capabilities . . . . . . . . . . . . . . . . . 64 5.1. CI/T Endpoint Capability Object . . . . . . . . . . . . . 64 5.1.1. CI/T Endpoints Capability Object Serialization . . . 65 5.2. CI/T Trigger Scope Capability Object . . . . . . . . . . 66 5.2.1. CI/T Trigger Scope Capability Object Serialization . 68 5.3. CI/T Object List Type Capability Object . . . . . . . . . 68 5.3.1. CI/T Object List Type Capability Object Serialization . . . . . . . . . . . . . . . . . . . . 69 5.4. CI/T Private URL Capability Object . . . . . . . . . . . 69 5.4.1. CI/T Private URL Type Capability Object Serialization . . . . . . . . . . . . . . . . . . . . 69 5.5. CI/T Extended Status Capability Object . . . . . . . . . 70 5.5.1. CI/T Private URL Type Capability Object Serialization . . . . . . . . . . . . . . . . . . . . 70 6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 71 6.1. Creating Triggers . . . . . . . . . . . . . . . . . . . . 71 6.1.1. Preposition . . . . . . . . . . . . . . . . . . . . . 71 6.1.2. Invalidate . . . . . . . . . . . . . . . . . . . . . 73 6.1.3. Invalidation with Regex . . . . . . . . . . . . . . . 75 6.1.4. Preposition with ObjectLists . . . . . . . . . . . . 77 6.2. Examining Trigger Status . . . . . . . . . . . . . . . . 78 6.2.1. Collection of All Triggers . . . . . . . . . . . . . 78 6.2.2. Filtered Collections of Triggers . . . . . . . . . . 80 6.2.3. Individual Trigger Resources . . . . . . . . . . . . 81 6.2.4. Polling for Changes in Status . . . . . . . . . . . . 83 6.2.5. Deleting Triggers . . . . . . . . . . . . . . . . . . 85 6.2.6. Extensions with Error Propagation . . . . . . . . . . 87 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 90 7.1. CDNI Payload Type Parameter Registrations . . . . . . . . 90 7.1.1. CDNI ci-trigger.v2 Payload Type . . . . . . . . . . . 91 7.1.2. CDNI FCI CI/T Payload Types . . . . . . . . . . . . . 91 7.2. "CDNI CI/T Trigger Types" Registry For Trigger Actions . 92 7.3. "CDNI CI/T Trigger Specs" Registry . . . . . . . . . . . 92 7.4. "CDNI CI/T Trigger Subjects" Registry . . . . . . . . . . 93 7.5. "CDNI CI/T Object List Types" Registry . . . . . . . . . 93 7.6. "CDNI CI/T Trigger Extensions" Registry . . . . . . . . . 93 7.7. "CDNI CI/T Error Codes" Registry . . . . . . . . . . . . 94 7.8. "CDNI CI/T URL Types" Registry . . . . . . . . . . . . . 94 8. Security Considerations . . . . . . . . . . . . . . . . . . . 94 8.1. Authentication, Authorization, Confidentiality, Integrity Protection . . . . . . . . . . . . . . . . . . . . . . . 95 8.2. Denial of Service . . . . . . . . . . . . . . . . . . . . 96 8.3. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 96 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 97 9.1. Normative References . . . . . . . . . . . . . . . . . . 97 Sopher, et al. Expires 24 April 2025 [Page 3] Internet-Draft CDN Interconnect Triggers October 2024 9.2. Informative References . . . . . . . . . . . . . . . . . 98 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 99 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 99 1. Introduction [RFC6707] introduces the problem scope for Content Delivery Network Interconnection (CDNI) and lists the four categories of interfaces that may be used to compose a CDNI solution (Control, Metadata, Request Routing, and Logging). [RFC7336] expands on the information provided in [RFC6707] and describes each of the interfaces and the relationships between them in more detail. The CDNI Control Interface / Triggers 1st edition [RFC8007], deprecated by this document, describes the "CI/T" interface -- "CDNI Control interface / Triggers". It does not consider those parts of the Control interface that relate to configuration, bootstrapping, or authentication of CDN Interconnect interfaces. Section 4 of [RFC7337] identifies the requirements specific to the CI/T interface; requirements applicable to the CI/T interface are CI-1 to CI-6. This document is a second edition of the CDNI Control Interface / Triggers, which defines a new version, "v2", of the interface objects. The new objects replace the trigger interface's main objects, the "ci-trigger-command" object and its matching "ci- trigger-status" object with "ci-trigger.v2" object to support REST [REST] architectural style in a way that improves the interface's flexibility, extensibility and interoperability, and allows encoding the interface using OpenAPI. The second edition of the CI/T interface further allows use of separate Control interface endpoints for content and metadata. The document also provides a Trigger Extension mechanism that MAY be used to provide further instruction on the trigger execution. This second edition also includes cascaded CDN error propagation and extended trigger status reporting for improved trigger execution monitoring, as well as use of external object lists for improved scale and integration of trigger-based APIs with existing content workflows. * Section 2 outlines the model for the CI/T interface at a high level. Sopher, et al. Expires 24 April 2025 [Page 4] Internet-Draft CDN Interconnect Triggers October 2024 * Section 3 defines the CI/T interface offered by the downstream CDN. * Section 4 defines encoding of the standard CI/T objects, and introduces trigger spec and trigger extension types. * Section 5 describes the FCI capabilities objects used to inform on the supported CI/T-related capabilities. * Section 6 contains example messages. 1.1. Terminology This document reuses the terminology defined in [RFC6707] and uses "uCDN" and "dCDN" as shorthand for "upstream CDN" and "downstream CDN", respectively. Additionally, the following terms are used throughout this document and are defined as follows: * HLS - HTTP Live Streaming * DASH - Dynamic Adaptive Streaming Over HTTP * MSS - Microsoft Smooth Streaming The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 2. Model for CDNI Triggers 2.1. REST Architecture The CI/T interface utilizes HTTP/1.1 protocol [RFC9112] and follows the principles of the Representational State Transfer (REST) architectural style. uCDN, in its capacity of a CI/T interface client, makes a request to dCDN to carry out an action ("trigger") related to metadata or content stored by dCDN on behalf of uCDN. dCDN, as a CI/T interface server, governs the triggers as a set of resources, which can be dynamically created and deleted, and whose state can be retrieved and/or modified by uCDN. Each such trigger is identified by a unique Uniform Resource Identifier (URI) is defined in Section 4.2 of [RFC9110]. Sopher, et al. Expires 24 April 2025 [Page 5] Internet-Draft CDN Interconnect Triggers October 2024 Once a trigger is created, uCDN can retrieve its trigger state from dCDN or request its state to be modified by transferring an updated representation of the trigger state to dCDN. The CI/T interface supports representation of trigger resources using JSON [RFC8259]. This RESTful data model built around a common "trigger" resource replaces the command-oriented model of [RFC8007], wherein uCDN passed commands to dCDN using "ci-trigger-command" objects, and dCDN generated "ci-trigger-status" objects in response. 2.2. HTTP Methods Section 9.3 of [RFC9110] defines the set of methods in HTTP. The CI/ T interface uses some of these methods for resource creation, retrieval of resource state, modification of resources and deletion of resources. The HTTP methods not listed here are not supported by the CI/T interface. * GET - used to retrieve the current state of a resource. The GET method doesn't cause any state change on the server side. * POST - used to request that the target resource process the representation enclosed in the request. If a resource has been created on the server as a result of successfully processing a POST request, the server sends a 201 (Created) response containing a Location header field that contains an identifier for the newly created resource. * DELETE - used to request the server remove the target resource. * HEAD - used to request metadata associated with the target resource, in the form of HTTP response headers that would have been sent if the GET method was used instead. The HEAD method can be used to verify that the target resource exists at the server. 2.3. Trigger To request that an action be carried by dCDN, uCDN requests to create a trigger resource. If dCDN accepts the request, it creates a new Trigger resource and returns its unique URI to uCDN. uCDN MUST use this URI for all requests associated with the created Trigger resource. uCDN can only access Trigger resources it created. Note that the version of the Trigger resources that uCDN requests to create MUST match the version of CI/T Trigger objects reported as supported by dCDN. Sopher, et al. Expires 24 April 2025 [Page 6] Internet-Draft CDN Interconnect Triggers October 2024 The CI/T interface supports the following types of trigger action:: * preposition - used to instruct dCDN to fetch metadata from the uCDN or content from any origin including uCDN. * invalidate - used to instruct dCDN to revalidate specific metadata or content before reusing it. * purge - used to instruct dCDN to delete specific metadata or content. Note that additional action types can be defined and registered in the future. The trigger resource has a state attribute. dCDN creates new triggers in "pending" state. Once dCDN starts processing a trigger, the trigger state is set to "active". Once the the trigger processing is complete, the state is set to either "complete" or "failed", depending on the processing outcome. uCDN MAY request dCDN to cancel a trigger. If such request is accepted, the trigger state is changed to "cancelling", and when the cancellation is complete, the trigger state changes to "cancelled". For full description of the Trigger resource, please refer to Section 4.1. 2.4. Trigger Collection Trigger Collection is a resource that represents one or more trigger resources, belonging to particular uCDN. dCDN maintains one Trigger Collection resource for each uCDN. Each uCDN only has access to its own collection resource. dCDN supports retrieval of multiple representations of the trigger collection resource. The supported trigger collection representations are listed in Section 4.2, and include filtering of Trigger resources by Trigger State and Trigger Label attributes. Note that additional trigger collection representations can be defined and registered in the future. 2.5. Session Overview Figure 1 is an example showing the basic message flow in a CI/T interface session used by the uCDN to trigger activity in dCDN and for uCDN to discover the status of that activity. Only successful triggering is shown. Examples of the messages are shown in Section 6. Sopher, et al. Expires 24 April 2025 [Page 7] Internet-Draft CDN Interconnect Triggers October 2024 uCDN dCDN | (1) POST https://dcdn.example.com/triggers/uCDN | [ ] --------------------------------------------------> [ ]--+ | [ ] | (2) | (3) HTTP 201 Response [ ]<-+ [ ] <-------------------------------------------------- [ ] | Loc: https://dcdn.example.com/triggers/uCDN/123 | | | . . . . . . . . . | | | (4) GET https://dcdn.example.com/triggers/uCDN/123 | [ ] --------------------------------------------------> [ ] | [ ] | (5) HTTP 200 Trigger resource representation [ ] [ ] <-------------------------------------------------- [ ] | | | | | (6) DELETE https://dcdn.example.com/triggers/uCDN/123 | [ ] --------------------------------------------------> [ ]--+ | [ ] | (7) | (8) HTTP 200 OK [ ]<-- [ ] <-------------------------------------------------- [ ] | | Figure 1: Basic CDNI Message Flow for Triggers The steps in Figure 1 are as follows: 1. uCDN requests to create a new Trigger resource by POSTing its representation to the trigger collection resource with a well- known URI "https://dcdn.example.com/triggers/uCDN". 2. dCDN authenticates the request, validates the Trigger resource in it, and if the request is accepted, creates a new Trigger resource. 3. dCDN responds to uCDN with an HTTP 201 response status and the location of the Trigger resource. 4. uCDN MAY query, possibly repeatedly, the Trigger resource in dCDN. 5. dCDN responds to each query with the current Trigger resource representation, including the trigger state, that reflects the progress of the uCDN request. Sopher, et al. Expires 24 April 2025 [Page 8] Internet-Draft CDN Interconnect Triggers October 2024 6. Once the trigger reaches a terminal state ("complete", "failed" or "cancelled"), uCDN MAY request to delete Trigger resource. 7. dCDN validates the request and the trigger resource state. If successful, the trigger resource is removed by the server, and subsequent requests for this resource MUST result in 404 (Not Found). 8. dCDN responds to the deletion request with 200 (OK) status code. 2.6. Trigger Processing 2.6.1. Timing and Order uCDN MAY place limits on timing and order of execution of a trigger through optional TimePolicy (Section 4.1.3.3.2) and/or ExecutionPolicy (Section 4.1.3.3.3) extensions. If neither of these extensions are present in the trigger resource, the timing and order of the trigger execution is under dCDN's control, including start time, pacing of the activity in the network and order in which dCDN chooses to process pending triggers. The CI/T "invalidate" and "purge" trigger actions MUST be applied to all data acquired before dCDN begins the trigger processing (i.e. enters "active" state). dCDN implementation SHOULD apply "invalidate" and "purge" triggers to content acquisition that is in progress when the trigger becomes active, to avoid placing purged or invalidated content into cache upon completion of the content acquisition. dCDN SHOULD NOT apply CI/T "invalidate" and "purge" actions to data acquired after the trigger processing started, but this may not always be achievable, so uCDN cannot count on that. If uCDN wishes to invalidate or purge content and then immediately preposition replacement content at the same URLs, it SHOULD ensure that dCDN has completed the invalidate/purge before initiating the prepositioning. Otherwise, there is a risk that the dCDN prepositions the new content, then immediately invalidates or purges it (as a result of the two uCDN requests running in parallel). uCDN MAY use the Execution Policy (Section 4.1.3.3.3) extension to condition the start of preposition trigger processing on completion of the earlier invalidate/purge trigger(s). 2.6.2. Scope Each trigger can operate on multiple metadata and content elements, usually referred to by their URLs. These elements are targeted by specifying both their subject (i.e., "metadata" or "content") as well as specification method (e.g., URL Regexes) and value. Sopher, et al. Expires 24 April 2025 [Page 9] Internet-Draft CDN Interconnect Triggers October 2024 Multiple representations of an HTTP resource may share the same URL. Triggers that invalidate or purge metadata or content apply to all resource representations with matching URLs. 2.6.3. Results Possible trigger states are defined in Section 4.1.4. Trigger state MUST NOT be reported as "complete" until all operations listed in the trigger have been completed successfully. The reasons for failure, and URLs or patterns affected, SHOULD be made available in the trigger state representation. For more details, see Section 3.8. 2.7. Trigger Extensibility The CDNI Control Interface / Triggers 1st edition [RFC8007] defines a set of properties and objects used by the trigger commands. This 2nd edition defines an extension mechanism to the triggers interface that enables applications to add instructions for finer control over the trigger execution, for example indicating a time window in which to execute the trigger. This document specifies a generic trigger extension object wrapper for managing individual CDNI trigger extensions in an opaque manner. All trigger extensions are optional, and it is thus the responsibility of the extension specification to define a consistent default behavior for the case the extension is not present. All trigger extensions MUST be registered in the IANA "CDNI CI/T Trigger Extensions" registry (see Section 7.6). This document also defines an initial set of trigger extension objects and registers them in the IANA "CDNI CI/T Trigger Extensions" registry: Sopher, et al. Expires 24 April 2025 [Page 10] Internet-Draft CDN Interconnect Triggers October 2024 +==================+=========================================+ | JSON String | Description | +==================+=========================================+ | location-policy | Allowing the control over the locations | | | in which the trigger is executed. | +------------------+-----------------------------------------+ | time-policy | Allowing the scheduling of a trigger to | | | run in a specific time window. | +------------------+-----------------------------------------+ | execution-policy | Allowing the control over the order and | | | timing in which triggers are executed. | +------------------+-----------------------------------------+ Table 1 Example use cases * Preposition with cache location policy * Purge content with cache location policy * Preposition at a specific time * Purge by content acquisition time (e.g., purge all content acquired in the past X hours) 2.8. Multiple Interconnected CDNs In a network of interconnected CDNs, a single uCDN will originate a given item of metadata and associated content. It MAY distribute that metadata and content to one or more dCDNs, which in turn distributes that metadata and content to additional dCDNs located further downstream. An intermediate CDN is dCDN that passes on CDNI Metadata and content to dCDNs located further downstream. A "diamond" configuration is one where dCDN can acquire metadata and content originated in one uCDN from that uCDN itself and an intermediate CDN, or via more than one intermediate CDN. Triggers originating in the single source uCDN affect metadata and content in all dCDNs; however, in a diamond configuration, it may not be possible for dCDN to determine from which uCDN it acquired content. In this case, dCDN MUST allow each uCDN from which it may have acquired the content to act upon that content using triggers. Sopher, et al. Expires 24 April 2025 [Page 11] Internet-Draft CDN Interconnect Triggers October 2024 In all other cases, dCDN MUST reject triggers from uCDN that attempts to act on another uCDN's content by responding, for example, with an HTTP 403 ("Forbidden"). Security considerations are discussed further in Section 8. The diamond configuration may lead to inefficient interactions, but the interactions are otherwise harmless. For example: * When uCDN requests to create an "invalidate" trigger, dCDN will receive that request from multiple directly connected uCDNs. The dCDN may schedule multiple such triggers separately, and the last scheduled trigger may affect content already revalidated following execution of the "invalidate" trigger that was scheduled first. * If one of dCDN's directly connected uCDNs loses its rights to distribute content, it may issue a "purge" trigger. That purge may affect content dCDN could retain because it's distributed by another directly connected uCDN. But, that content can be reacquired by dCDN from the remaining uCDN. * When uCDN originating an item of content issues a purge followed by a preposition, two directly connected uCDNs will pass those triggers to a dCDN. That dCDN implementation need not merge those operations or notice the repetition, in which case the purge issued by one uCDN will be completed before the other. The first uCDN to finish its purge may then forward the "preposition" trigger, and content prepositioned as a result might be affected by the still-running purge issued by the other uCDN. However, dCDN will reacquire that content as needed, or when it's asked to preposition the content by the second uCDN. dCDN implementation could avoid this interaction by knowing which uCDN it acquired the content from, or it could minimize the consequences by recording the time at which the "invalidate"/"purge" trigger was received and not applying it to content acquired after that time. If dCDN is also acting as uCDN in a cascade, it MUST forward trigger requests to any dCDNs that may be affected. The trigger state MUST NOT be reported as "complete" by an intermediate CDN until it is "complete" in all of its dCDNs and in the intermediate CDN itself. If a trigger is reported as "processed" in the intermediate CDN or any one of its dCDNs, intermediate CDNs MUST report trigger as "processed" as well. If a trigger is reported as "failed" by the intermediate CDN or any one of its dCDNs, the intermediate CDN must report the trigger as "failed" only after its processing is finished in it and all of its dCDNs. A cancelled trigger MUST be reported as "cancelling" until it has been reported as "cancelled", "complete", or "failed" by all dCDNs in a cascade. Sopher, et al. Expires 24 April 2025 [Page 12] Internet-Draft CDN Interconnect Triggers October 2024 3. CDNI Trigger Interface This section describes an interface to enable uCDN to trigger activity in dCDN. The CI/T interface builds on top of HTTP, so dCDNs may make use of any HTTP feature when implementing the CI/T interface. For example, dCDN SHOULD make use of HTTP's caching mechanisms to indicate that a requested resource representation has not been modified, reducing uCDN's processing needed to determine whether the status of a trigger has changed. dCDNs MAY implement separate CI/T interfaces per Section 4.1.2.2, i.e. one CI/T interface for trigger operations on metadata and another for operations on content. In this case, dCDN MUST advertise separate interface endpoints via Section 5.1. All dCDNs implementing CI/T MUST support the HTTP GET, HEAD, POST, and DELETE methods as defined in [RFC9110]. The only resource representation specified in this document is JSON [RFC8259]. It MUST be supported by uCDN and by dCDN. The CI/T interface uses a root URL for retrieval of the Trigger Collection resource and creation of new triggers. The mechanism for discovery of that URL is part of the CI/T interface bootstrapping and is outside the scope of this document. uCDN requests to create a new Trigger resource by POSTing its representation to the root interface URL, discovered at the time of interface bootstrapping, e.g. "https://dcdn.example.com/triggers/ uCDN". If the request is accepted by dCDN, it creates a new Trigger resource and returns its URI to uCDN in an HTTP 201 response. Once created, the new trigger URI also becomes available via the trigger collection resource described in Section 4.2. Additionally, uCDN may discover the URIs of multiple trigger collection representations using the interface root URL. This means that the URIs for all trigger resources and trigger collection representations can be discovered by uCDN, so dCDNs are free to assign whatever structure they desire to the URIs for CI/T resources. Therefore, uCDNs MUST NOT make any assumptions regarding the structure of CI/T URIs or the mapping between CI/T objects and their associated URIs. The URIs used in the examples in this document are purely illustrative and are not intended to impose a definitive structure on CI/T interface implementations. Sopher, et al. Expires 24 April 2025 [Page 13] Internet-Draft CDN Interconnect Triggers October 2024 3.1. Creating Triggers To create a new trigger, uCDN makes an HTTP POST request with the trigger representation to the root interface URL. The trigger representation MUST include the mandatory attributes of trigger resource (Section 4.1). uCDN MAY also optionally specify optional trigger v2 specification attributes, namely trigger labels and trigger extensions, as well as the optional "cdn-path" attribute of the trigger resource. dCDN validates the trigger resource representation sent by uCDN. If the representation is malformed or uCDN does not have sufficient access rights, dCDN MUST either respond with an appropriate 4xx HTTP error code and not create a trigger resource or create a trigger resource with "failed" state and an appropriate Error.v2 Description (Section 4.1.5.1). The new trigger resource is created in "pending" state. If successful, The HTTP response to the uCDN trigger creation request MUST have status code 201 (Accepted) and MUST convey the URI of the newly created trigger resources in the Location response header field [RFC9110]. The HTTP response SHOULD include the updated representation of the trigger resource. This is particularly important in cases where dCDN processed the trigger immediately. Once a trigger resource has been created, dCDN MUST NOT reuse its URI, even after the trigger resource has been fully removed. It is therefore recommended that dCDN utilize unique UUID identifiers as specififed in [RFC9562]. dCDN SHOULD provide continuous updates of the trigger processing progress, by responding with updated trigger resource representations to subsequent uCDN requests sent to the created trigger URL. If the dCDN is unable to do that, it MUST indicate that it has accepted the request but will not be providing further status updates. To do this, it MUST set the trigger state to "processed" at creation time. In this case, CI/T processing should continue as it were a request in the "complete" state. In this case dCDN SHOULD also provide an estimated completion time for the request by using the trigger "etime" property. Otherwise dCDN MUST set the state of the new trigger to "pending". Once trigger processing has started, the status MUST be changed to "active". Finally, once the the trigger processing is complete, the trigger state MUST be set to "complete" or "failed". Sopher, et al. Expires 24 April 2025 [Page 14] Internet-Draft CDN Interconnect Triggers October 2024 Once created, trigger resources can be cancelled, modified or deleted by uCDN, subject to constraints described below. 3.2. Modifying Triggers Modification of existing triggers is useful for uCDN to correct an error in trigger specification or trigger extension(s) that may govern when the trigger is to be processed. uCDN can request modification of an existing trigger resource by sending an updated trigger representation to the trigger URI using HTTP POST command. dCDN MAY accept modifications of the trigger specifications, trigger extensions and trigger labels, when the trigger is in "pending" state, i.e. dCDN didn't start its processing yet. dCDN MAY also accept a request to change the trigger state subject to the following constraints: * the requested state is "cancelled", and the trigger was in either "pending" or "active" state when dCDN receives the request * the requested state is "active", and the trigger was in "pending" state when dCDN received the request The Section 3.3 describes processing of the trigger cancellation requests in detail. uCDN MAY request to set the trigger state to "active" to prompt dCDN to re-examine the trigger resource and start its processing immediately. dCDN MUST respond to the trigger modification request appropriately. Thus, the HTTP status code 200 ("OK") should be returned if the modification has been processed, 202 ("Accepted") if the command has been accepted but the modification is not fully complete yet, 404 ("Not Found") when the trigger resource does not exist, 409 ("Conflict") when the trigger resource is in a state that doesn't allow the requested modification, 501 ("Not Implemented") if the modification is not supported by dCDN or an appropriate 4xx HTTP error code in case of a malformed request. In case of successful 2xx response, dCDN MUST provide the updated trigger resource representation in the response body. Sopher, et al. Expires 24 April 2025 [Page 15] Internet-Draft CDN Interconnect Triggers October 2024 3.3. Cancelling Triggers uCDN MAY request cancellation of a trigger by requesting its state to be set to "cancelled", as described in Section 3.2. dCDN MUST respond to such request, however the actual cancellation of a trigger resource is optional to implement. dCDN MUST respond to the trigger cancellation request appropriately. dCDN MUST respond with the HTTP status code 200 ("OK") if the trigger processing has been cancelled and the trigger state has been set to "cancelled", 202 ("Accepted") if the command has been accepted but the trigger processing has not been cancelled yet, 404 ("Not Found") when the trigger resource does not exist, or 501 ("Not Implemented") if cancellation is not supported by dCDN. If cancellation of a "pending" trigger is accepted by dCDN, dCDN SHOULD NOT start the processing of that activity. Requesting a cancellation of a "pending" trigger does not, however, guarantee that the corresponding activity will not be started, because uCDN cannot control the timing of that activity. Processing could, for example, start after the POST is sent by uCDN but before that request is processed by dCDN. If cancellation of an "active" or "processed" trigger is accepted by dCDN, dCDN SHOULD stop processing the trigger. However, as with the cancellation of a "pending" trigger, dCDN does not guarantee that the trigger processing doesn't run to completion in the meantime. If uCDN cannot stop the trigger processing immediately after receiving the request from uCDN to do so, it MUST set the trigger state to "cancelling" and provide this state in the trigger representation in its response. If the trigger processing is stopped before its normal completion, the trigger state MUST be set to "cancelled". Cancellation of a "complete", "failed" or "cancelled" trigger requires no processing in dCDN. Its state MUST NOT be changed. 3.4. Checking Status uCDN has two ways to check the progress of its triggers' processing, as described in Section 3.4.1 and Section 3.4.2. To allow uCDN to use client-side caching of all triggers and trigger collections, dCDN SHOULD include an ETag response header with every resource representation it sends. dCDN SHOULD also respond with the HTTP code 304 ("Not Modified") without a response body in response to conditional resource requests that use "If-None-Match" and/or "If- Sopher, et al. Expires 24 April 2025 [Page 16] Internet-Draft CDN Interconnect Triggers October 2024 Modified-Since" request headers as described in Section 13 of [RFC9110] , in case dCDN doesn't have a more recent resource representation. dCDN SHOULD use the cache control headers for responses to GET requests for its resources to indicate the frequency at which it recommends that uCDN and/or intermediate proxies should poll for change. If provided, uCDN should match the frequency of polling to the cache control information provided by dCDN. 3.4.1. Polling Trigger Collections uCDN MAY fetch the trigger collection or one of filtered representations of it. This makes it possible for uCDN to poll the status of all trigger resources or selected trigger subsets, filtered by trigger state or by trigger label. In this way, uCDN is able to monitor trigger state changes by polling the representation of the trigger collection filtered by trigger state. 3.4.1.1. Trigger resource collection: extended view representation If dCDN advertises support for extended status, uCDN MAY request the extended trigger collection representation, which embeds full representations of trigger resources in the collection resource. The extended representation is supported for all filtered representations of the trigger collection, so it is possible to retrieve all trigger resource representations for a specific trigger state (e.g. all triggers in "pending" state). uCDN SHOULD request the extended representation by passing the query string parameter "status=extended" when requesting a trigger collection resource or one of its filtered representations. dCDN SHOULD appropriately respond to the request for extended status with HTTP Status 200 ("OK") when such request can be satisfied, with error code 501 ("Not Implemented") if the capability has not been implemented or advertised, and 400 ("Bad Request") when dCDN encounters a malformed query format. By default, trigger resources are represented in the trigger collection with their resource URL only. Sopher, et al. Expires 24 April 2025 [Page 17] Internet-Draft CDN Interconnect Triggers October 2024 3.4.2. Polling Triggers uCDN has a URI provided by dCDN at the trigger creation time. Alternatively, uCDN MAY discover trigger resource URI by retrieving the trigger collection resource and/or one of its filtered representations. It may fetch an up-to-date representation of the trigger resource at any time using HTTP GET request, including changes in trigger state, as well as the outcome of the trigger processing. 3.5. Deleting Triggers uCDN MAY request delete trigger resources at any time using the HTTP DELETE method. As defined in the CDNI Control Interface / Triggers 1st edition [RFC8007], Once deleted, the deleted trigger MUST be removed from all representations of the trigger collection. Subsequent requests to the trigger resource URI MUST be rejected by dCDN with HTTP error 404 ("Not Found"). the effect of deletion is similar to cancellation, except that the trigger resource becomes unavailable after the deletion is complete. For this reason, uCDN SHOULD cancel triggers rather than delete them when it is important for uCDN to access the trigger status after the trigger processing is stopped. If a "pending" trigger is deleted, dCDN SHOULD NOT start the processing of that activity. Deleting a "pending" trigger does not, however, guarantee that its processing has not started, because uCDN cannot control the timing of that activity. Processing may, for example, start after the DELETE is sent by uCDN but before that request is processed by dCDN. When an "active" or "processed" trigger is deleted, the dCDN SHOULD stop processing it. However, as with deletion of a "pending" trigger, dCDN does not guarantee this. Deletion of a "complete", "cancelled" or "failed" trigger no processing in dCDN. dCDN MUST respond to the trigger deletion request appropriately. dCDN MUST respond with the HTTP status code 200 ("OK") without a response body if the trigger has been deleted immediately. 202 ("Accepted") if the command has been accepted but the trigger has not been deleted yet. 404 ("Not Found") when the trigger resource does not exist, or 501 ("Not Implemented") if deletion is not supported by dCDN. Sopher, et al. Expires 24 April 2025 [Page 18] Internet-Draft CDN Interconnect Triggers October 2024 The trigger state MUST be set to "cancelling" while dCDN is processing a deletion request asynchronously. 3.6. Expiry of Triggers dCDN MAY automatically delete trigger resources sometime after they reach a terminate state (one of "complete", "processed", "failed", or "cancelled"). In this case, after dCDN removed such trigger, it MUST respond to subsequent requests for it with the HTTP error 404 ("Not Found") and remove it from the trigger collection resource. If dCDN does remove triggers in a terminal state automatically, it MUST report the expiry timeout period, using an attribute of the trigger collection resource. It is RECOMMENDED that dCDN sets its expiry timeout to at least 24 hours. It is further RECOMMENDED that uCDN sets its trigger polling period to less than the expiry period, so it doesn't miss trigger status updates before the "complete" or "failed" triggers are expired by dCDN. 3.7. Loop Detection and Prevention Given three CDNs, A, B, and C, if CDNs B and C delegate delivery of CDN A's content to each other, CDN A's trigger creation requests could be passed between CDNs B and C in a loop. More complex networks of CDNs could contain similar loops involving more hops. To prevent and detect such CI/T loops, each CDN uses a CDN Provider ID (PID) (Section 4.3.3). to uniquely identify itself. In every trigger resource it creates or cascades, each CDN MUST append an array element containing its CDN PID to a JSON array under an entry named "cdn-path". When receiving a trigger creation request, dCDN MUST check the cdn-path and reject any trigger that already contains its own CDN PID in the cdn-path. Transit CDNs MUST check the "cdn- path" and not cascade the trigger creation request to dCDNs that are already listed in the cdn-path. 3.8. Error Handling dCDN MAY reject CI/T interface requests, by responding to those requests with 4xx or 5xx HTTP status codes. For example, uCDN MAY respond with 400 ("Bad Request") if the request is malformed, or 403 ("Forbidden") or 404 ("Not Found") if the request could not be properly authenticated or if uCDN is trying to act on another CDN's resources. Sopher, et al. Expires 24 April 2025 [Page 19] Internet-Draft CDN Interconnect Triggers October 2024 If any part of the trigger processing fails, the trigger SHOULD be reported as "failed" once its activity is complete or if no further errors will be reported. The "errors" property in the trigger will be used to enumerate which actions failed and the reasons for failure, and can be present while the trigger is still "pending" or "active" if the trigger processing is still running for some URLs or patterns in the trigger specs. Once a request has been accepted, processing errors are reported in the trigger using a list of Error.v2 Descriptions. Each Error.v2 Description is used to report errors against one or more of the URLs or patterns in the Trigger Specification. If a Surrogate affected by a trigger is offline in the dCDN or dCDN is unable to pass a trigger on to any of its cascaded dCDNs: * If the trigger is abandoned by dCDN, dCDN SHOULD report an error. * A CI/T "invalidate" command may be reported as "complete" when Surrogates that may have the data are offline. In this case, Surrogates MUST NOT use the affected data without first revalidating it when they are back online. * CI/T "preposition" and "purge" commands can be reported as "processed" if affected caches are offline and the activity will complete when they return to service. * Otherwise, dCDN SHOULD keep the trigger "pending" or "active" state until either the trigger is acted upon or uCDN chooses to cancel it. 3.8.1. Error Propagation This subsection explains the mechanism for enabling uCDN to trace an error back to dCDN in which it occurred. CDNI triggers may be propagated over a chain of downstream CDNs. For example, an upstream CDN A (uCDN-A) that is delegating to a downstream CDN B (dCDN-B) and dCDN-B is delegating to a downstream CDN C (dCDN-C). Triggers sent from uCDN-A to dCDN-B may be redistributed from dCDN-B to dCDN-C, and errors can occur anywhere along the path. Therefore, it might be essential for uCDN-A that sets the trigger, to be able to trace back an error to the downstream CDN where it occurred. This document adds a mechanism to propagate the PID of dCDN where the fault occurred, back to the uCDN by adding the PID to the error.v2 description. When dCDN-B propagates a trigger further to the downstream dCDN-C, it MUST also propagate back the errors received in the trigger status resource from dCDN-C by adding them to the errors array in its own status resource to be sent back to the originating uCDN-A. While Sopher, et al. Expires 24 April 2025 [Page 20] Internet-Draft CDN Interconnect Triggers October 2024 propagating back the errors dCDN-B MAY also specify dCDN-C PID, indicating to which CDN the error specifically relates. The trigger originating upstream CDN then receives an array built of the errors that occurred in all the CDNs along the execution path, where each error MAY carry its own CDN identifier. Figure 2 below is an example showing the message flow used by uCDN-A to trigger activity in dCDN-B, followed by dCDN-C, as well as the discovery of the status of that activity, including the Error Propagation. uCDN-A dCDN-B dCDN-C | | | | (1) POST | | | https://dcdn-b.example.com | | | /triggers/uCDN-A | | [ ]--------------------------->[ ]--+ | | [ ] | (2) | | [ ]<-+ | | (3) HTTP 201 Response. [ ] | |<----------------------------[ ] | | Loc: [ ] | | https://dcdn-b.example.com [ ] (4) POST | | /triggers/uCDN-A/123 [ ] https://dcdn-c.example.com | | [ ] /triggers/dCDN-B | (5) | [ ]--------------------------->[ ]--+ | | [ ] | | | [ ]<-+ | | (6) HTTP 201 Response. [ ] | [ ]<---------------------------[ ] | | Loc: | | | https://dcdn-c.example.com | | | /triggers/dCDN-B/456 | | | | | [ ]--+ | | [ ] | (7.1) | | [ ]<-+ [ ]--+ | | (7.2) [ ] | | | [ ]<-+ | | | . . . . . . . . . | | (8) GET | | | https://dcdn-c.example.com | | | /triggers/dCDN-B/456 | | [ ]--------------------------->[ ] | | [ ] Sopher, et al. Expires 24 April 2025 [Page 21] Internet-Draft CDN Interconnect Triggers October 2024 | | (9) HTTP 200 [ ] | | Trigger resource [ ] | [ ]<---------------------------[ ] | | | . . . . . . . . . | (10) GET | | | https://dcdn-b.example.com | | | /triggers/uCDN-A/123 | | [ ]--------------------------->[ ] | | [ ] | | (11) HTTP 200 [ ] | | Trigger resource [ ] | [ ]<---------------------------[ ] | Figure 2: CDNI Message Flow for Triggers, Including Error Propagation The steps in Figure 2 are as follows: 1. uCDN-A triggers an action in dCDN-B by POSTing a trigger representation to a triggers collection URI "https://dcdn- b.example.com/triggers/uCDN-A". This URL was given to uCDN-A when the CI/T interface was established. 2. dCDN-B authenticates the request, validates the trigger creation request, and, if it accepts the request, creates a new trigger resource. 3. dCDN-B responds to uCDN-A with an HTTP 201 response status and the location of the newly created trigger. 4. dCDN-B triggers the action in dCDN-C by POSTing a trigger representation to a triggers collection URI "https://dcdn- c.example.com/triggers/dCDN-B". This URL was given to dCDN-B when the CI/T interface was established. 5. dCDN-C authenticates the request, validates the trigger creation request, and, if it accepts the request, creates a new trigger resource. 6. dCDN-C responds to dCDN-B with an HTTP 201 response status and the location of the newly created trigger resource. Sopher, et al. Expires 24 April 2025 [Page 22] Internet-Draft CDN Interconnect Triggers October 2024 7. dCDN-C acts upon the trigger. However, the command fails at dCDN-C as, for example, the trigger definition contains an "action" type that is not supported by dCDN-C. dCDN-C's action is depicted by 7.2 in the diagram, while 7.1 shows dCDN-B acting on its own trigger. 8. dCDN-B queries, possibly repeatedly, the trigger resource in dCDN-C. 9. dCDN-C responds with the trigger resource representation, describing the progress or results of the trigger processing. In the described flow, the trigger state is "failed", with an Error.v2 Description object holding "eunsupported" Error Code reflecting the reason. 10. uCDN-A queries, possibly repeatedly, the trigger status in dCDN- B. 11. dCDN-B responds with the updated trigger resource representation, describing the progress or results of trigger processing. In the flow described above, the trigger state is "failed", and the "eunsupported" error received in the trigger status from dCDN-C is propagated along with dCDN-C PID by adding it to the errors array in dCDN-B's own status resource to be sent back to the originating uCDN-A. 4. CI/T Object Properties and Encoding Trigger and Trigger Collection resources as well as their properties, are encoded using JSON, as defined in Section 4.1, and Section 4.2, respectively. When sending the JSON-based representation of these resources, the MIME media type "application/cdni" MUST be used, with parameter "ptype" values as defined below and in Section 7.1. Names in JSON are case-sensitive. The names and literal values specified in the present document MUST always use lowercase. JSON types, including "object", "array", "number", and "string", are defined in [RFC8259]. Unrecognized name/value pairs in JSON objects SHOULD NOT be treated as an error by either uCDN or dCDN. They SHOULD be ignored during processing and passed on by dCDN to any further dCDNs in a cascade. Sopher, et al. Expires 24 April 2025 [Page 23] Internet-Draft CDN Interconnect Triggers October 2024 4.1. Trigger Resource Trigger resource is encoded as a JSON object and MUST use a MIME media type of "application/cdni; ptype=ci-trigger.v2". The rigger resource contains the following name/value pairs: Name: action Description: Defines the type of the CI/T Trigger Action. Value: Trigger Action Type, as defined in Section 4.1.1. Mandatory: Yes. Name: specs Description: Array of trigger specs representing the trigger's targets, as described in Section 4.1.2. Value: Array of GenericTriggerSpec objects (see Section 4.1.2.1). Mandatory: Yes. Furthermore, the list MUST NOT be empty. Name: extensions Description: Array of trigger extensions, as described in Section 4.1.3. Value: Array of GenericTriggerExtension objects (see Section 4.1.3.2). Mandatory: No. The default is no extensions. Name: labels Description: Array of trigger labels. Value: Array of Trigger labels, Each label is encoded as a JSON string and SHOULD be unique per trigger. Mandatory: No. The default is no labels. Name: cdn-path Description: The chain of CDN PIDs of CDNs that have already created this trigger resource. Value: Non-empty array of JSON strings, where each string is a CDN PID as defined in Section 4.3.3. Mandatory: No. The default is no CDN path. Sopher, et al. Expires 24 April 2025 [Page 24] Internet-Draft CDN Interconnect Triggers October 2024 Name: ctime Description: The time at which the trigger resource was received by the dCDN. The time is determined by dCDN; there is no requirement to synchronize clocks between interconnected CDNs. Value: A JSON number, seconds since the UNIX epoch (00:00:00 UTC on 1 January 1970). Mandatory: Yes. Name: mtime Description: The time at which the trigger resource was last modified. The time is determined by dCDN; there is no requirement to synchronize clocks between interconnected CDNs. Value: A JSON number, seconds since the UNIX epoch (00:00:00 UTC on 1 January 1970). Mandatory: Yes. Name: etime Description: The estimate of the time at which dCDN expects to complete the trigger processing. Time is determined by dCDN; there is no requirement to synchronize clocks between interconnected CDNs. Value: A JSON number, seconds since the UNIX epoch (00:00:00 UTC on 1 January 1970). Mandatory: No. Name: state Description: The current trigger state. Value: Trigger state, as defined in Section 4.1.4. Mandatory: No. Name: state-reason Description: A human-readable explanation for the object state. Value: A JSON string, the human-readable reason. Mandatory: No. Name: errors Sopher, et al. Expires 24 April 2025 [Page 25] Internet-Draft CDN Interconnect Triggers October 2024 Description: Descriptions of errors that have occurred while processing the trigger. Value: An array of Error.v2 Descriptions, as defined in Section 4.1.5.1. An empty array is allowed and is equivalent to omitting "errors" from the object. Mandatory: No. Name: objects Description: List of objects derived by dCDN when processing the trigger. Value: An array of ObjectList (Section 4.3.2) objects. dCDN SHOULD provide the list of objects it used as input for processing the trigger with Section 4.1.2.7, provided that dCDN advertised support for extended status (Section 5.5). An empty array is allowed and is equivalent to omitting "objects" from the trigger representation. This field is intended to provide the list of all objects used in processing. The objects that failed to process SHOULD be specified using the Error.v2 Description resource. Mandatory: No. 4.1.1. Trigger Action Trigger Action is used in a trigger resource to describe trigger actions. It was initially referred to in [RFC8007] as "Trigger Type". All trigger actions MUST be registered in the IANA "CDNI CI/T Trigger Types" registry (see Section 7.2). dCDN receiving a request containing a trigger action that it does not recognize or does not support MUST reject the request by creating a trigger with "failed" state and the "errors" array containing an Error.v2 Description with error "eunsupported" (see Section 4.1.5.2). The following trigger actions are defined by this document: Sopher, et al. Expires 24 April 2025 [Page 26] Internet-Draft CDN Interconnect Triggers October 2024 +=============+============================================+ | JSON String | Description | +=============+============================================+ | preposition | A request for dCDN to acquire metadata or | | | content. | +-------------+--------------------------------------------+ | invalidate | A request for dCDN to invalidate metadata | | | or content. After servicing this request, | | | dCDN will not use the specified data | | | without first revalidating it using, for | | | example, an "If-None-Match" HTTP request. | | | dCDN need not erase the associated data. | +-------------+--------------------------------------------+ | purge | A request for dCDN to erase metadata or | | | content. After servicing the request, the | | | specified data MUST NOT be held on dCDN | | | (dCDN should reacquire the metadata or | | | content from uCDN if it needs it). | +-------------+--------------------------------------------+ Table 2 4.1.2. Trigger Specs The CDNI Control Interface / Triggers 1st edition [RFC8007] defines a set of properties and objects used by the trigger commands in order to specify the targets upon which the trigger is applied. This document modifies the trigger interface objects so it has a list of trigger specs. Such structure improves the interface's extensibility and flexibility. Furthermore, the document defines a generic trigger spec object that acts as a wrapper for managing individual CDNI trigger specs in an opaque manner, allowing future extension of the interface. All trigger specs MUST be registered in the IANA "CDNI CI/T Trigger Specs" registry (see Section 7.3). dCDN receiving a trigger creation request containing a trigger spec that it does not recognize or does not support MUST reject the request by creating a trigger resource with "failed" state and the "errors" array containing an Error.v2 Description with error "espec" (see Section 4.1.5.2). This document also defines an initial set of trigger spec objects and registers them in the IANA "CDNI CI/T Trigger Specs" registry: Sopher, et al. Expires 24 April 2025 [Page 27] Internet-Draft CDN Interconnect Triggers October 2024 +====================+========================================+ | JSON String | Description | +====================+========================================+ | urls | Allowing the specification of trigger | | | targets via URLs. | +--------------------+----------------------------------------+ | ccids | Allowing the specification of trigger | | | targets via CCIDs content grouping, as | | | defined in section 4.2.8 [RFC8006]. | +--------------------+----------------------------------------+ | uri-pattern-match | Allowing the specification of trigger | | | targets via [RFC3986] URI patterns. | +--------------------+----------------------------------------+ | uri-regex-match | Allowing the specification of trigger | | | targets via regexes matching their | | | URI, as defined in Section 4.1.2.6. | +--------------------+----------------------------------------+ | content-objectlist | Allowing the specification of trigger | | | targets via an object list and an | | | object list type. | +--------------------+----------------------------------------+ Table 3 Each trigger usually refers to the targets by the target URLs, using a "urls" trigger spec object or some aggregating spec such as the "url-regex-match". If content URLs are transformed by an intermediate CDN in a cascade, that intermediate CDN MUST similarly transform URLs in triggers it passes to its dCDNs. When processing a trigger, CDNs MUST ignore the URL scheme (HTTP or HTTPS) in comparing URLs. For example, for a CI/T "invalidate" or "purge" action, content MUST be invalidated or purged regardless of the protocol clients used to request it. 4.1.2.1. Generic Spec Object A trigger resource, as defined in Section 4.1, includes an array of trigger spec objects. Each trigger spec object contains properties that are used as trigger target selection directives for dCDN when processing the trigger. e.g. content URLs or metadata URI patterns. Each such trigger spec is a specialization of a CDNI GenericTriggerSpec object. The GenericTriggerSpec object abstracts the basic information required for trigger distribution from the specifics of any given property (i.e., property semantics, enforcement options, etc.). Sopher, et al. Expires 24 April 2025 [Page 28] Internet-Draft CDN Interconnect Triggers October 2024 The semantics of the trigger specs list is additive, i.e., the trigger applies to any object matching one of the listed specs. A GenericSpecObject object is a wrapper for managing individual CDNI Trigger specs in an opaque manner. It is encoded as a JSON object containing the following name/value pairs: Name: trigger-subject Description: Case-insensitive CDNI Trigger subject. Value: String containing the type of the subject matching the generic-trigger-spec-value property, such as "content" or "metadata" as defined in Section 4.1.2.2. Mandatory: Yes. Name: generic-trigger-spec-type Description: Case-insensitive CDNI Trigger spec type. Value: String containing the spec type of the object contained in the generic-trigger-spec-value property (see table in Section 4.1.2). Mandatory: Yes. Name: generic-trigger-spec-value Description: A CDNI Trigger spec object. Value: Defined by the value of the generic-trigger-spec-type property. Mandatory: Yes. The structure of a JSON-serialized GenericTriggerSpec object, containing a specific trigger spec is illustrated below: Sopher, et al. Expires 24 April 2025 [Page 29] Internet-Draft CDN Interconnect Triggers October 2024 { "generic-trigger-spec-type": , "generic-trigger-spec-value": { }, "generic-trigger-spec-subject": } 4.1.2.2. Trigger Subject Because the scope of the trigger may relate to either metadata as well as content, the "trigger spec object" also specifies the trigger's target subject (i.e., metadata or content) against which to match. All trigger subjects MUST be registered in the IANA "CDNI CI/T Trigger Subjects" registry (see Section 7.4). dCDN receiving a trigger creation request containing a trigger subject that it does not recognize or does not support MUST reject the request by creating a trigger resource with "failed" state and the "errors" array containing an Error.v2 Description with error "esubject" (see Section 4.1.5.2). This document also defines an initial set of trigger subject values and registers them in the IANA "CDNI CI/T Trigger Subjects" registry: +=============+====================================================+ | JSON String | Description | +=============+====================================================+ | metadata | Indicating the trigger target specification refers | | | to Metadata object(s), as defined at [RFC8006]. | +-------------+----------------------------------------------------+ | content | Indicating the trigger target specification refers | | | to client-facing content objects. | +-------------+----------------------------------------------------+ Table 4 4.1.2.3. URLs Spec The "urls" spec type allows uCDN to manage uCDN content or metadata objects held by dCDN based on the objects' URLs. Sopher, et al. Expires 24 April 2025 [Page 30] Internet-Draft CDN Interconnect Triggers October 2024 The URLs spec is encoded as a JSON object containing the following name/value pairs: Name: urls Description: An array of URLs over which the trigger MUST be executed. Value: A JSON array of URLs represented as JSON strings. Mandatory: Yes. Name: url-type Description: Type of URL used. Value: URL Type as defined in Section 4.3.1. Mandatory: No. When omitted or empty, "published" URL type is assumed. Below is an example of a JSON-serialized URLs spec object, matching the metadata at metadata.example.com/a/b/c. { "trigger-subject": "metadata", "generic-trigger-spec-type": "urls", "generic-trigger-spec-value": { "urls": [ "https://metadata.example.com/a/b/c" ], "url-type": "published" } } 4.1.2.4. CCIDs Spec The "ccids" spec type allows uCDN to specify the Content Collection IDentifier (CCID) of content to which the trigger applies. The CCID is a grouping of content as defined by [RFC8006]. The "ccids" spec type is valid only for the content spec subject (see Section 4.1.2.2). CCIDs spec is encoded as a JSON object containing the following name/ value pairs: Name: ccids Description: An array of Content Collection IDentifiers over which the trigger MUST be executed. Value: A JSON array of strings, where each string is a Content Collection IDentifier. Sopher, et al. Expires 24 April 2025 [Page 31] Internet-Draft CDN Interconnect Triggers October 2024 Mandatory: Yes. 4.1.2.5. URI Pattern Match Spec The "uri-pattern-match" spec type allows uCDN to manage uCDN content or metadata objects held by dCDN based on the objects' URI pattern. The value is a UriPatternMatch object, as defined in Section 4.1.2.5.1. 4.1.2.5.1. UriPatternMatch A UriPatternMatch consists of a string pattern to match against a URI, and flags describing the type of match. It is encoded as a JSON object containing the following name/value pairs: Name: pattern Description: A pattern for URI matching. Value: A JSON string representing the pattern. The pattern can contain the wildcards "*" and "?", where "*" matches any sequence of [RFC3986] pchar or "/" characters (including the empty string) and "?" matches exactly one [RFC3986] pchar character. The three literals "$", "*" and "?" MUST be escaped as "$$", "$*" and "$?" (where "$" is the designated escape character). All other characters are treated as literals. Mandatory: Yes. Name: case-sensitive Description: Flag indicating whether or not case-sensitive matching should be used. Value: One of the JSON values "true" (the matching is case sensitive) or "false" (the matching is case insensitive). Mandatory: No; default is "false", i.e., a case-insensitive match. Name: match-query-string Description: Flag indicating whether to include the query part of the URI when compared against the pattern. Sopher, et al. Expires 24 April 2025 [Page 32] Internet-Draft CDN Interconnect Triggers October 2024 Value: One of the JSON values "true" (the full URI, including the query part, should be compared against the given pattern) or "false" (the query part of the URI should be dropped before comparison with the given pattern). Mandatory: No; default is "false". The query part of the URI should be dropped before comparison with the given pattern. Name: url-type Description: Type of URLs to match. Value: URL Type as defined in Section 4.3.1. Mandatory: No. When omitted or empty, "published" URL type is assumed. Example of case-sensitive prefix match against "https://www.example.com/trailers/": { "pattern": "https://www.example.com/trailers/*", "case-sensitive": true } 4.1.2.6. URI Regex Match Spec The "uri-regex-match" spec type allows uCDN to manage content or metadata objects held by dCDN based on the objects' URI regex. 4.1.2.6.1. RegexMatch A RegexMatch consists of a regular expression string a URI is matched against, and flags describing the type of match. It is encoded as a JSON object with the following properties: Name: regex Description: A regular expression for URI matching. Value: A regular expression to match against the URI, i.e., against the path-absolute and the query string parameters [RFC3986]. The regular expression string MUST be compatible with POSIX [POSIX.1] Section 9 Extended Regular Expressions. This regular expression MUST be evaluated in the POSIX locale (POSIX [POSIX.1] Section 7.2). Note: Because '\' has a special meaning in JSON [RFC8259] as the escape character within JSON strings, the regular expression character '\' MUST be escaped as '\\'. Sopher, et al. Expires 24 April 2025 [Page 33] Internet-Draft CDN Interconnect Triggers October 2024 Mandatory: Yes. Name: case-sensitive Description: Flag indicating whether or not case-sensitive matching should be used. Value: JSON boolean. Either "true" (the matching is case- sensitive) or "false" (the matching is case insensitive). Mandatory: No; default is "false", i.e., a case-insensitive match. Name: match-query-string Description: Flag indicating whether to include the query part of the URI when compared against the regex. Value: JSON Boolean. Either "true" (the full URI, including the query part, should be compared against the regex) or "false" (the query part of the URI should be dropped before comparison with the given regex). Mandatory: No; default is "false". The query part of the URI MUST be dropped before comparison with the given regex. This makes the regular expression simpler and safer for cases in which the query parameters are not relevant for the match. Name: url-type Description: Type of URLs to match against. Value: URL Type as defined in Section 4.3.1. Mandatory: No. When omitted or empty, "published" URL type is assumed. Example of a case-sensitive, no query parameters, regex match against is below. Please note that some lines in the example are wrapped for clarity. "^(https:\/\/video\.example\.com)\/([a-z])\/ movie1\/([1-7])\/*(index.m3u8|\d{3}.ts)$" { "regex": "^(https:\\/\\/video\\.example\\.com)\\/([a-z])\\/ movie1\\/([1-7])\\/*(index.m3u8|\\d{3}.ts)$", "case-sensitive": true, "match-query-string": false } Sopher, et al. Expires 24 April 2025 [Page 34] Internet-Draft CDN Interconnect Triggers October 2024 This regex matches URLs of the domain "video.example.com" where the path structure is /(single lower case letter)/(name-of-title)/(single digit between 1 to 7)/(index.m3u8 or a 3 digit number with ts extension). For example: https://video.example.com/d/movie1/5/index.m3u8 or https://video.example.com/k/movie1/4/013.ts 4.1.2.7. Object List Spec The "objectlist" spec type allows uCDN to manage content held by dCDN based on structured object lists. The Object List spec type is valid only for the content spec subject (see Section 4.1.2.2). An object list is encoded as a JSON object with the following properties: Name: objects Description: An array of objects to be used in the trigger Value: ObjectList (Section 4.3.2) object Mandatory: Yes. 4.1.3. Trigger Extensions A "trigger" object, as defined in Section 4.1 includes an optional array of trigger extension objects. A trigger extension contains properties that are used as directives for dCDN when executing the trigger command, e.g., location policies, time policies, and so on. Each such CDNI Trigger extension is a specialization of a CDNI GenericTriggerExtension object. The GenericTriggerExtension object abstracts the basic information required for trigger distribution from the specifics of any given property (i.e., property semantics, enforcement options, etc.). All trigger extensions are optional, and it is thus the responsibility of the extension specification to define a consistent default behavior for extensions supported by dCDN when not specified by uCDN. 4.1.3.1. Enforcement Options The trigger enforcement options concept is in accordance with the metadata enforcement options as defined in Section 3.2 of [RFC8006]. Sopher, et al. Expires 24 April 2025 [Page 35] Internet-Draft CDN Interconnect Triggers October 2024 The GenericTriggerExtension object defines the properties contained within it as well as whether or not the properties are "mandatory-to- enforce". If dCDN does not understand or support a mandatory-to- enforce property, dCDN MUST NOT execute the trigger command. If the extension is not mandatory-to-enforce, then that GenericTriggerExtension object can be safely ignored and the trigger command can be processed in accordance with the rest of the CDNI Trigger spec. Although a CDN MUST NOT execute a trigger command if a mandatory-to- enforce extension cannot be enforced, it could still be safe to redistribute that trigger (the "safe-to-redistribute" property) to another CDN without modification. For example, in the cascaded CDN case, a transit CDN (tCDN) could convey mandatory-to-enforce trigger extension to dCDN. For a trigger extension that does not require customization or translation (i.e., trigger extension that is safe- to-redistribute), the data representation received off the wire MAY be stored and redistributed without being understood or supported by tCDN. However, for trigger extension that requires translation, transparent redistribution of uCDN trigger values might not be appropriate. Certain trigger extensions can be safely, though perhaps not optimally, redistributed unmodified. For example, preposition command might be executed in suboptimal times for some geographies if transparently redistributed, but it might still work. Redistribution safety MUST be specified for each GenericTriggerExtension listed. If a CDN does not understand or support a given GenericTriggerExtension object that is not safe-to- redistribute, the CDN MUST set the "incomprehensible" flag to true for that GenericTriggerExtension object before redistributing it. The "incomprehensible" flag signals to dCDN that trigger metadata was not properly transformed by the tCDN. A CDN MUST NOT attempt to execute a trigger with an extension that has been marked as "incomprehensible" by uCDN. tCDNs MUST NOT change the value of mandatory-to-enforce or safe-to- redistribute when propagating a trigger to dCDN. Although a tCDN can set the value of "incomprehensible" to true, a tCDN MUST NOT change the value of "incomprehensible" from true to false. Table 5 describes the action to be taken by a tCDN for the different combinations of mandatory-to-enforce ("MtE") and safe-to-redistribute ("StR") properties when the tCDN either does or does not understand the trigger extension object in question: Sopher, et al. Expires 24 April 2025 [Page 36] Internet-Draft CDN Interconnect Triggers October 2024 +=======+=======+============+=================================+ | MtE | StR | Extension | Trigger action | | | | object | | | | | understood | | | | | by tCDN | | +=======+=======+============+=================================+ | False | True | True | Can execute and redistribute. | +-------+-------+------------+---------------------------------+ | False | True | False | Can execute and redistribute. | +-------+-------+------------+---------------------------------+ | False | False | False | Can execute. MUST set | | | | | "incomprehensible" to true when | | | | | redistributing. | +-------+-------+------------+---------------------------------+ | False | False | True | Can execute. Can redistribute | | | | | after transforming the trigger | | | | | extension (if the CDN knows how | | | | | to do so safely); otherwise, | | | | | MUST set "incomprehensible" to | | | | | true when redistributing. | +-------+-------+------------+---------------------------------+ | True | True | True | Can execute and redistribute. | +-------+-------+------------+---------------------------------+ | True | True | False | MUST NOT execute but can | | | | | redistribute. | +-------+-------+------------+---------------------------------+ | True | False | True | Can execute. Can redistribute | | | | | after transforming the trigger | | | | | extension (if the CDN knows how | | | | | to do so safely); otherwise, | | | | | MUST set "incomprehensible" to | | | | | true when redistributing. | +-------+-------+------------+---------------------------------+ | True | False | False | MUST NOT serve. MUST set | | | | | "incomprehensible" to true when | | | | | redistributing. | +-------+-------+------------+---------------------------------+ Table 5: Action to be taken by a tCDN for the different combinations of MtE and StR properties Table 6 describes the action to be taken by dCDN for the different combinations of mandatory-to-enforce and "incomprehensible" ("Incomp") properties, when dCDN either does or does not understand the trigger extension object in question: Sopher, et al. Expires 24 April 2025 [Page 37] Internet-Draft CDN Interconnect Triggers October 2024 +=======+========+==================+==========================+ | MtE | Incomp | Extension object | Trigger action | | | | understood by | | | | | dCDN | | +=======+========+==================+==========================+ | False | False | True | Can execute. | +-------+--------+------------------+--------------------------+ | False | True | True | Can execute but MUST NOT | | | | | interpret/apply any | | | | | trigger extension marked | | | | | as "incomprehensible". | +-------+--------+------------------+--------------------------+ | False | False | False | Can execute. | +-------+--------+------------------+--------------------------+ | False | True | False | Can execute but MUST NOT | | | | | interpret/apply any | | | | | trigger extension marked | | | | | as "incomprehensible". | +-------+--------+------------------+--------------------------+ | True | False | True | Can execute. | +-------+--------+------------------+--------------------------+ | True | True | True | MUST NOT execute. | +-------+--------+------------------+--------------------------+ | True | False | False | MUST NOT execute. | +-------+--------+------------------+--------------------------+ | True | True | False | MUST NOT execute. | +-------+--------+------------------+--------------------------+ Table 6: Action to be taken by dCDN for the different combinations of MtE and Incomp properties 4.1.3.2. GenericExtensionObject A GenericTriggerExtension object is a wrapper for managing individual CDNI Trigger extensions in an opaque manner. It is encoded as a JSON object containing the following name/value pairs: Name: generic-trigger-extension-type Description: Case-insensitive CDNI Trigger extension object type. Value: String containing the CDNI Extension Type [RFC7736] of the object contained in the "generic-trigger-extension-value" property (see table in Section 2.7). Mandatory: Yes. Sopher, et al. Expires 24 April 2025 [Page 38] Internet-Draft CDN Interconnect Triggers October 2024 Name: generic-trigger-extension-value Description: CDNI Trigger extension object. Value: Defined by the value of the "generic-trigger-extension- type" property above. Mandatory: Yes. Name: mandatory-to-enforce Description: Flag identifying whether or not the enforcement of this trigger extension is mandatory. Value: Boolean. Mandatory: No. The default is to treat the trigger extension as mandatory to enforce (i.e., a value of True) Name: safe-to-redistribute Description: Flag identifying whether or not this trigger extension can be safely redistributed without modification, even if the CDN fails to understand the extension. Value: Boolean. Mandatory: No. The default is to allow transparent redistribution (i.e., a value of True). Name: incomprehensible Description: Flag identifying whether or not any CDN in the chain of delegation has failed to understand and/or failed to properly transform this trigger extension object. Note: This flag only applies to trigger extension objects whose "safe-to- redistribute" property has a value of False. Value: Boolean. Mandatory: No. The default is comprehensible (i.e., a value of False). The structure of a JSON-serialized GenericTriggerExtension object containing a specific trigger extension object is illustrated below: Sopher, et al. Expires 24 April 2025 [Page 39] Internet-Draft CDN Interconnect Triggers October 2024 { "generic-trigger-extension-type": , "generic-trigger-extension-value": { }, "mandatory-to-enforce": , "safe-to-redistribute": , "incomprehensible": } 4.1.3.3. Trigger Extension Objects The objects defined below are intended to be used in the GenericTriggerExtension object's generic-trigger-extension-value field as defined in Section 4.1.3.2, and their generic-trigger- extension-type property MUST be set to the appropriate Extension Type as defined in Section 2.7. 4.1.3.3.1. LocationPolicy Extension A content operation may be relevant for a specific geographical region or need to be excluded from a specific region. In this case, the trigger should be applied only to parts of the network that are either "included" or "not excluded" by the location policy. Note that the restrictions here are on the cache location rather than the client location. The LocationPolicy object defines which CDN or cache locations for which the trigger command is relevant. Example use cases: * Preposition: Certain contracts allow for prepositioning or availability of contracts in all regions except for certain excluded regions in the world, including caches. For example, some content cannot ever knowingly touch servers in a specific country, including cached content. Therefore, these regions MUST be excluded from a prepositioning operation. * Purge: In certain cases, content may have been located on servers in regions where the content must not reside. In such cases, a purge operation to remove content specifically from that region is required. Object specification: Sopher, et al. Expires 24 April 2025 [Page 40] Internet-Draft CDN Interconnect Triggers October 2024 Name: locations Description: An Access List that allows or denies (blocks) the trigger execution per cache location. Value: Array of LocationRule objects (see Section 4.2.2.1 of [RFC8006]). Mandatory: Yes. Name: url-type Description: Type of URL used in the ObjectList(s). Value: URL Type as defined in Section 4.3.1. Mandatory: No. When omitted or empty, the "published" URL type is assumed. If a location policy object is not listed within the trigger command, the default behavior is to execute the trigger in all available caches and locations of dCDN. The trigger command is allowed, or denied, for a specific cache location according to the action of the first location whose footprint matches that cache's location. If two or more footprints overlap, the first footprint that matches against the cache's location determines the action a CDN MUST take. If the "locations" property is an empty list or if none of the listed footprints match the location of a specific cache location, then the result is equivalent to a "deny" action. The following is an example of a JSON-serialized generic trigger extension object containing a location policy object that allows the trigger execution in the US but blocks its execution in Canada: Sopher, et al. Expires 24 April 2025 [Page 41] Internet-Draft CDN Interconnect Triggers October 2024 { "generic-trigger-extension-type": "location-policy", "generic-trigger-extension-value": { "locations": [ { "action": "allow", "footprints": [{ "footprint-type": "countrycode", "footprint-value": [ "us" ] }] }, { "action": "deny", "footprints": [{ "footprint-type": "countrycode", "footprint-value": [ "ca" ] }] } ] }, "mandatory-to-enforce": true, "safe-to-redistribute": true, "incomprehensible": false } 4.1.3.3.2. TimePolicy Extension uCDN may wish to perform content management operations on dCDN on a specific schedule. The TimePolicy extension allows uCDN to instruct dCDN to execute the trigger command in a desired time window. For example, a content provider that wishes to pre-populate a new episode at off-peak time so that it would be ready on caches at prime time when the episode is released for viewing. A scheduled operation enables uCDN to direct dCDN in what time frame to execute the trigger. uCDN may wish to schedule a trigger such that dCDN will execute it in local time, as it is measured in each region. For example, uCDN may wish dCDN to pull the content at off-peak hours, between 2AM-4AM, however, as a CDN is distributed across multiple time zones, the UTC definition of 2AM depends on the actual location. We define two alternatives for localized scheduling: Sopher, et al. Expires 24 April 2025 [Page 42] Internet-Draft CDN Interconnect Triggers October 2024 * Regional schedule: When used in conjunction with the Location Policy defined in Section 4.1.3.3.1, uCDN can trigger separate commands for different geographical regions, for each region using a different schedule. This allows uCDN to control the execution time per region. * Local Time schedule: We introduce a "local time" version for Internet timestamps that follows the notation for local time as defined in Section 4.2.2 of [ISO8601]. When local time is used, that dCDN SHOULD execute the triggers at different absolute times, according to the local time of each execution location. Object specification: Name: unix-time-window Description: A UNIX epoch time window in which the trigger SHOULD be executed. Value: TimeWindow object using UNIX epoch timestamps (see Section 4.2.3.2 of [RFC8006]). Mandatory: No, but exactly one of "unixEpochWindow" or "utcWindow" MUST be present. Name: utc-window Description: A UTC time window in which the trigger SHOULD be executed. Value: UTCWindow object as defined in Section 4.1.3.3.2.1. Mandatory: No, but exactly one of "unixEpochWindow" or "utcWindow" MUST be present. If a time policy object is not listed within the trigger command, the default behavior is to execute the trigger in a time frame most suitable to dCDN taking under consideration other constraints and / or obligations. Example of a JSON-serialized generic trigger extension object containing a time policy object that schedules the trigger execution to a window between 09:00 01/01/2000 UTC and 17:00 01/01/2000 UTC, using the "unix-time-window" property: Sopher, et al. Expires 24 April 2025 [Page 43] Internet-Draft CDN Interconnect Triggers October 2024 { "generic-trigger-extension-type": "time-policy", "generic-trigger-extension-value": { "unix-time-window": { "start": 946717200, "end": 946746000 } }, "mandatory-to-enforce": true, "safe-to-redistribute": true, "incomprehensible": false } 4.1.3.3.2.1. UTCWindow A UTCWindow object describes a time range in UTC or UTC and a zone offset that can be applied by a TimePolicy. It is encoded as a JSON object containing the following name/value pairs: Name: start Description: The start time of the window. Value: Internet date and time as defined in [RFC3339]. Mandatory: No. but at least one of "start" or "end" MUST be present and non-empty. Name: end Description: The end time of the window. Value: Internet date and time as defined in [RFC3339]. Mandatory: No. but at least one of "start" or "end" MUST be present and non-empty. Example JSON-serialized UTCWindow object that describes a time window from 02:30 01/01/2000 UTC to 04:30 01/01/2000 UTC: { "start": "2000-01-01T02:30:00.00Z", "end": "2000-01-01T04:30:00.00Z" } Sopher, et al. Expires 24 April 2025 [Page 44] Internet-Draft CDN Interconnect Triggers October 2024 Example JSON-serialized UTCWindow object that describes a time window in New York time zone offset UTC-05:00 from 02:30 01/01/2000 to 04:30 01/01/2000: { "start": "2000-01-01T02:30:00.00-05:00", "end": "2000-01-01T04:30:00.00-05:00" } 4.1.3.3.3. ExecutionPolicy Extension Unless specified otherwise, dCDN is at liberty to decide how to choose trigger commands for execution from all pending commands, whether to process trigger commands sequentially or in parallel, immediately upon acceptance, or with a delay in batches. uCDN may wish to control trigger processing in more detail, including the order of execution, dependencies, and concurrency. Example use cases: * Priority: uCDN may have multiple trigger commands in "pending" and/or "active" mode. For example, trigger commands with policy constraints, a large number of content objects affected, or other dCDN business logic may take a long time to execute. uCDN may wish to prescribe the order in which dCDN picks up its trigger commands for execution from the "pending" queue, by indicating a relative priority of each trigger. The priority would affect the selection of trigger commands specific to the requesting uCDN. dCDN may separately prioritize triggers from multiple uCDNs subject to its business logic. Multiple priority-related use cases exist: - uCDN needs to introduce an urgent "purge" or "invalidate" trigger into an existing queue of trigger commands to correct wrong versions of content objects published by it - uCDN needs to indicate which content objects should be prepositioned, purged or invalidated first, for example prepositioning newer released content before prepositioning updates to an existing catalog * Prerequisite: In some cases, uCDN may wish to indicate what trigger commands should be processed and completed before another trigger command is processed. For example, uCDN may want to rectify incorrectly published content by purging content objects and then prepositioning them again. In this case, uCDN may want the preposition trigger command to be processed only after the purge trigger command has been processed because concurrent Sopher, et al. Expires 24 April 2025 [Page 45] Internet-Draft CDN Interconnect Triggers October 2024 processing of these triggers may cause the new version of these content objects to be purged. Alternatively, uCDN may wish to condition the execution of purge or invalidation triggers upon the completion or cancellation of long-running preposition triggers to avoid race conditions that would result from processing these in parallel. The prerequisite requirement implies that a previous trigger reaches one of the following states: - "complete" or "processed" for successful completion - "failed" for failed processing - "cancelled" for completion of cancellation * Urgency: uCDN may wish to indicate that dCDN should process a trigger command without delay. This requirement is separate and additional to priority, as priority indicates the order in which triggers should be processed, yet does not prescribe how soon each trigger should be executed. dCDN MAY reject such requests for urgent processing using "ereject" error code. This can happen due to dCDN internal business logic (e.g. batch-driven purge and invalidation), or due to dependencies on other triggers that could not be completed by dCDN immediately. In such a case uCDN should either modify the request by removing prerequisites or cancel such pending triggers before re-trying the request. uCDN may combine multiple options in the same trigger command. dCDN should consider the following when processing such commands: * dCDN MUST reject triggers that are dependent on other pending triggers with lower priority to prevent deadlocks. * When introducing an urgent trigger uCDN SHOULD indicate a priority that is equal to or higher than the highest priority among the pending triggers that belong to the same uCDN. dCDN MUST reject urgent triggers that have lower priority than other pending triggers of the same uCDN. * dCDN MUST reject an urgent trigger that has pending triggers as its prerequisite. dCDN MAY reject an urgent trigger that has triggers in an "active" or "cancelling" state as its prerequisite, such as when such triggers are deemed to take a long time to complete or cancel. Sopher, et al. Expires 24 April 2025 [Page 46] Internet-Draft CDN Interconnect Triggers October 2024 When combining ExtensionPolicy with Section 4.1.3.3.2, TimePolicy governs the time window when the trigger can execute, while ExecutionPolicy controls the order of trigger execution within their respective windows. The following error conditions should be considered by dCDN: * When a trigger is marked urgent, but its TimePolicy extension doesn't allow immediate processing, it should be rejected by dCDN. * When a trigger has a TimePolicy extension and is also dependent on another trigger with a TimePolicy extension, that specifies an execution window (directly or via a chain of dependency) that doesn't start until after the depending trigger's execution window ends, such a trigger should be rejected. The ExtensionPolicy extension is encoded as a JSON object containing the following name/value pairs: Name: priority Description: Relative weight of the trigger. When picking a trigger for execution from all pending triggers posted by each uCDN, dCDN MUST choose the trigger with the highest priority first. Value: Integer from -100 to 100. Mandatory: No. The value defaults to zero if omitted. Name: depends Description: Links to trigger resources that the current trigger depends on. Indicates which triggers should fully finish processing before starting execution of the current trigger. The triggers need to be in one of the following states to be considered finished: "complete", "processed", "failed" or "cancelled". Value: A JSON array of zero or more URLs, represented as JSON strings. Mandatory: No. In case of a missing or an empty list, no dependencies are assumed. Name: urgent Description: Indicates whether the trigger should be immediately moved to the "active" state upon acceptance. In the absence of this flag, dCDN is at liberty to choose the time for trigger execution, e.g., batch processing. Sopher, et al. Expires 24 April 2025 [Page 47] Internet-Draft CDN Interconnect Triggers October 2024 Value: Boolean. Mandatory: No. The default is to handle the trigger as not urgent. The following is an example of a JSON-serialized generic extension trigger object containing an execution policy object that specifies trigger priority of 100, marks the trigger as urgent and makes its execution dependent on the completion of the previously created triggers : { "generic-trigger-extension-type": "execution-policy", "generic-trigger-extension-value": { "priority": 100, "depends": [ "https://dcdn.example.com/triggers/100", "https://dcdn.example.com/triggers/101" ], "urgent": true } } 4.1.4. Trigger State Trigger state describes the current state of the triggered activity. It MUST be one of the JSON strings in the following table: Sopher, et al. Expires 24 April 2025 [Page 48] Internet-Draft CDN Interconnect Triggers October 2024 +============+==============================================+ | JSON | Description | | String | | +============+==============================================+ | pending | The trigger has not yet been acted upon. | +------------+----------------------------------------------+ | active | The trigger is currently being acted upon. | +------------+----------------------------------------------+ | complete | The trigger processing completed | | | successfully. | +------------+----------------------------------------------+ | processed | The trigger has been created, and no further | | | status update will be made (can be used in | | | cases where completion cannot be confirmed). | +------------+----------------------------------------------+ | failed | The trigger processing could not be | | | completed. | +------------+----------------------------------------------+ | cancelling | The trigger processing is still in progress, | | | but the trigger has been cancelled by uCDN. | +------------+----------------------------------------------+ | cancelled | The trigger was cancelled by uCDN. | +------------+----------------------------------------------+ Table 7 Along with the trigger state, the Trigger resource has a state reason property, allowing dCDN to provide additional information for the trigger state. For example, dCDN may indicate that the trigger state is "pending" due to one of the execution prerequisites not being fulfilled. Such a prerequisite may be specified via one of the extensions. 4.1.5. Trigger Errors 4.1.5.1. Error.v2 Description An Error.v2 Description is used to report the failure of a trigger. It is encoded as a JSON object with the following name/value pairs: Name: error Value: Error Code, as defined in Section 4.1.5.2. Mandatory: Yes. Name: description Description: A human-readable description of the error. Sopher, et al. Expires 24 April 2025 [Page 49] Internet-Draft CDN Interconnect Triggers October 2024 Value: A JSON string, the human-readable description. Mandatory: No. Name: specs Description: Array of trigger spec objects from the corresponding "specs" array at the Trigger Specification. Only those specs to which the error applies are listed. Value: Array of Trigger Specifications, as defined in Section 4.1, where each spec object MUST be exactly as they appear in the request. Mandatory: Yes. Name: extensions Description: Array of trigger extension objects copied from the corresponding "extensions" array from the Trigger Specification. Only those extensions to which the error applies are included, but those extensions MUST be exactly as they appear in the request. Value: Array of GenericTriggerExtension objects, where each extension object is copied from the "extensions" array values in the Trigger Specification. Mandatory: No. The "extensions" array SHOULD be used only if the error relates to extension objects. Property omission should be interpreted as "the error is not related to any extension". Name: cdn-id Description: The CDN PID of the CDN where the error occurred. The "cdn-id" property is used by the originating uCDN or by the propagating dCDN in order to distinguish in which CDN the error occurred. Value: A non-empty JSON string, where the string is a CDN PID as defined in Section 3.7 Mandatory: Yes. dCDN may use its own CDN PID if it does not want to expose the CDN PIDs of dCDNs. Name: objects Description: List of objects that failed to be processed during trigger execution. Sopher, et al. Expires 24 April 2025 [Page 50] Internet-Draft CDN Interconnect Triggers October 2024 Value: An array of ObjectList (Section 4.3.2) objects. dCDN SHOULD provide the list of objects that it failed to process during trigger execution with Section 4.1.2.7, provided that dCDN advertised support for extended status (Section 5.5). Mandatory: No. An empty array is allowed and is equivalent to omitting "objects" from the Error.v2 Description. Example of a JSON-serialized Error.v2 Description object reporting a malformed object list : { "error": "econtent", "description": "Failed to parse HLS object list", "specs": [{ "trigger-subject": "content", "generic-trigger-spec-type": "content-objectlist", "generic-trigger-spec-value": { "objects": [{ "href": "https://www.example.com/hls/title/index.m3u8", "type": "hls" }] }} ], "objects": [{ "href": "https://www.example.com/hls/title/index.m3u8", "type": "hls" }], "cdn": "AS64500:0" } Example of a JSON-serialized Error.v2 Description object reporting an unsupported extension object: Sopher, et al. Expires 24 April 2025 [Page 51] Internet-Draft CDN Interconnect Triggers October 2024 { "errors": [{ "error": "eextension", "description": "unrecognized extension ", "specs": [{ "trigger-subject": "content", "generic-trigger-spec-type": "urls", "generic-trigger-spec-value": { "urls": [ "https://www.example.com/a/b/c/1", "https://www.example.com/a/b/c/2" ] } }], "extensions": [{ "generic-trigger-extension-type": "location-policy", "generic-trigger-extension-value": { "locations": [{ "action": "deny", "footprints": [{ "footprint-type": "countrycode", "footprint-value": [ "ca" ] }] }] } }], "cdn": "AS64500:0" }] } 4.1.5.2. Error Code This type is used by dCDN to report failures in trigger processing. All Error Codes MUST be registered in the IANA "CDNI CI/T Error Codes" registry (see Section 7.7). Unknown Error Codes MUST be treated as fatal errors, and the request MUST NOT be automatically retried without modification. The following Error Codes are defined by this document and MUST be supported by an implementation of the CI/T v2 interface. +==============+================================+==============+ | Error Code | Description | Registration | +==============+================================+==============+ | emeta | dCDN was unable to acquire | RFCthis | | | and/or is not in possession of | | | | metadata required to fulfill | | | | the request. | | Sopher, et al. Expires 24 April 2025 [Page 52] Internet-Draft CDN Interconnect Triggers October 2024 +--------------+--------------------------------+--------------+ | econtent | dCDN was unable to acquire | RFCthis | | | content (CI/T "preposition" | | | | commands only). | | +--------------+--------------------------------+--------------+ | eperm | uCDN does not have permission | RFCthis | | | to create the trigger as | | | | requested(for example, the | | | | data is owned by another CDN). | | +--------------+--------------------------------+--------------+ | ereject | dCDN is not willing to process | RFCthis | | | the trigger (for example, a | | | | "preposition" request for | | | | content at a time when dCDN | | | | would not accept Request | | | | Routing requests from uCDN). | | +--------------+--------------------------------+--------------+ | ecdn | An internal error in dCDN or | RFCthis | | | one of its dCDNs. | | +--------------+--------------------------------+--------------+ | ecancelled | uCDN cancelled the request. | RFCthis | +--------------+--------------------------------+--------------+ | eunsupported | The Trigger Specification | RFCthis | | | contained an "action type" | | | | that is not supported by dCDN. | | | | No action was taken by dCDN | | | | other than to create a trigger | | | | in a "failed" state. | | +--------------+--------------------------------+--------------+ | espec | An error occurred while | RFCthis | | | parsing a generic trigger | | | | spec, or that the specific | | | | trigger spec is not supported | | | | by the CDN. | | +--------------+--------------------------------+--------------+ | esubject | An error occurred while | RFCthis | | | parsing a trigger subject, or | | | | that the specific trigger | | | | subject is not supported by | | | | the CDN. | | +--------------+--------------------------------+--------------+ | eextension | An error occurred while | RFCthis | | | parsing a generic trigger | | | | extension, or that the | | | | specific extension is not | | | | supported by the CDN. | | +--------------+--------------------------------+--------------+ Sopher, et al. Expires 24 April 2025 [Page 53] Internet-Draft CDN Interconnect Triggers October 2024 Table 8 [RFC Editor: Please replace RFCthis with the published RFC number for this document.] 4.2. Trigger Collection Resource As described in Section 2, trigger resources exist in dCDN to represent a specific activity that uCDN requests dCDN to carry out. A collection of trigger resources is a resource that represents all triggers in it. By default trigger resources in a collection are represented using their unique URIs. Note that the collection may refer to CI/T Resources from several versions of CI/T objects, i.e., a subsequent call for the retrieval of the relevant trigger status may provide objects of various MIME media types: ci-trigger-status as defined in [RFC8007], ci-trigger.v2 defined in this document, or objects of future CI/T objects versions, based on the version of the JSON object used to create the trigger. dCDN MUST make a collection of uCDN's trigger resources available to that uCDN. This collection includes all triggers that have been created by uCDN and have not yet been deleted by uCDN (see Section 3.5) or expired and removed by dCDN (see Section 3.6). Trigger resources belonging to uCDN MUST NOT be visible to any other CDN. dCDN could, for example, achieve this by offering different collection URLs to each uCDN and by filtering the response based on uCDN with which the HTTP client is associated. To trigger an activity in dCDN or to cancel a triggered activity, the uCDN POSTs a trigger representation to dCDN's collection of uCDN's triggers. To allow uCDN to check the status of multiple triggers in a single request, dCDN MAY maintain optional representations of the trigger collection, that contain a subset of all triggers, filtered based on a parameter These filtered collection representations are "optional- to-implement", but if they are implemented, dCDN MUST include links to them in the trigger collection. dCDN MAY provide filtered collections per trigger state (Section 4.1.4). If implemented, dCDN SHOULD provide a separate filtered collection for every trigger state, and advertise these collections in the trigger collection. Sopher, et al. Expires 24 April 2025 [Page 54] Internet-Draft CDN Interconnect Triggers October 2024 dCDN MAY provide filtered collections per trigger label, as specified by uCDN when creating a trigger resource (Section 4.1). If implemented, dCDN SHOULD provide a separate filtered collection for every unique trigger label, and advertise these collections in the collection of all Trigger resources. Trigger Collections MUST use a MIME media type of "application/cdni; ptype=ci-trigger-collection". A Trigger Collection is encoded as a JSON object containing the following name/value pairs: Name: triggers Description: Links to triggers in the collection. Value: A JSON array of zero or more URLs, represented as JSON strings. Mandatory: Yes. Name: staleresourcetime Description: The length of time for which dCDN guarantees to keep a completed trigger resource. After this time, dCDN SHOULD delete the trigger resource and all references to it from the collection. Value: A JSON number, which must be a positive integer, representing time in seconds. Mandatory: Yes, in the collection of all triggers if dCDN deletes stale entries. If the property is present in the filtered collection representation, it MUST have the same value as in the collection of all triggers. Name: coll-state Description: Array of all Section 4.2.2 objects. Value: An array of JSON-encoded FilteredCollectionStatusLink objects. Mandatory: Mandatory in the collection of all triggers, if dCDN implements the filtered collections. Otherwise, optional. Name: coll-label Description: Array of all Section 4.2.1 objects. Value: An array of JSON-encoded FilteredCollectionLabelLink objects. Sopher, et al. Expires 24 April 2025 [Page 55] Internet-Draft CDN Interconnect Triggers October 2024 Mandatory: Mandatory in the collection of all triggers, if dCDN implements the filtered collections. Otherwise, optional. Name: all-triggers Description: Array of all triggers in the collection. Should be returned only when an extended trigger collection view is requested as described in Section 3.4.1.1. Value: An array of JSON-encoded triggers. Mandatory: No. The "all-triggers" SHOULD only be used by dCDN that supports and advertises the appropriate extended status for trigger collections (see Section 5.5 for details). Name: cdn-id Description: The CDN PID of dCDN. Value: A JSON string, dCDN's CDN PID, as defined in Section 3.7. Mandatory: Only in the collection of all triggers, if dCDN implements the filtered collections. Optional in the filtered collections (uCDN can always find dCDN's cdn-id in the collection of all triggers, but dCDN can choose to repeat that information in its implementation of filtered collections). 4.2.1. Filtered Collections by Status Link The Filtered Collections by state Link object represents a link to a filtered collection per trigger state (Section 4.1.4). It is encoded as a JSON object containing the following name/value pairs: Name: status Description: Trigger state matching the filtered collection. Value: A trigger State, as defined in Section 4.1.4. Mandatory: Yes. Name: collection Description: Filtered collection URL corresponding to the state. Value: A URL represented as a JSON string. Mandatory: Yes. Sopher, et al. Expires 24 April 2025 [Page 56] Internet-Draft CDN Interconnect Triggers October 2024 4.2.2. Filtered Collections by Label Link The Filtered Collections by Label Link object represents a link to a filtered collection per trigger label. It is encoded as a JSON object containing the following name/value pairs: Name: label Description: Trigger Label matching the filtered collection. Value: A Trigger Label, as defined in Section 4.1. Mandatory: Yes. Name: collection Description: Filtered collection URL corresponding to the label. Value: A URL represented as a JSON string. Mandatory: Yes. 4.3. Other CI/T Objects This section describes common CI/T objects and their encodings. 4.3.1. URL Type This type is used by uCDN to indicate how to interpret URLs referenced by trigger specs that use URLs, such as Section 4.1.2.3, Section 4.1.2.5, Section 4.1.2.6 and Section 4.1.2.7. One option for uCDN to use in triggers is published URLs, which are used by end users. When using this URL type, uCDN MUST provide configuration metadata objects related to these URLs before creating a trigger option referencing these URLs. When this is not the case, dCDN MUST return the error code "emeta". When processing published URLs in "preposition" Trigger Action, dCDN MUST invoke processing of metadata objects it would have invoked in content acquisition to satisfy an end-user request, e.g. SourceMetadata (see Section 4.2.1 of [RFC8006]). Another type of URL in common use is a private URL, which is based on cache keys that are dynamically constructed via lightweight processing of various properties of the HTTP request and/or response. As an example, an origin might specify a cache key as a value returned in a specific HTTP response header. Sopher, et al. Expires 24 April 2025 [Page 57] Internet-Draft CDN Interconnect Triggers October 2024 As an example, uCDN may prefer to use such private URLs in "purge" or "invalidate" Trigger Actions to simplify processing. dCDNs implementing the CI/T Interface MUST support the "published" URL type. dCDN MAY support the additional "private" URL type. In this case, dCDN SHOULD advertise the private URL type support via FCI using Section 5.4. If the private URL is not supported by dCDN, it SHOULD reject the trigger creation request using "eunsupported" Error Code. If both URL types are supported by dCDN, uCDN MUST use only one URL type in each trigger. The following URL types are defined by this document and MUST be supported by the implementation of the CI/T interface: +===========+==================================+==============+ | URL Type | Description | Registration | +===========+==================================+==============+ | published | Published URL used by end users | RFCthis | | | to access content | | +-----------+----------------------------------+--------------+ | private | Private URLs used by dCDN to | RFCthis | | | look up content objects in cache | | +-----------+----------------------------------+--------------+ Table 9 [RFC Editor: Please replace RFCthis with the published RFC number for this document.] 4.3.2. ObjectList ObjectList is a metadata object describing lists of objects that can be used in the context of CI/T v2 trigger spec, trigger status resources and other contexts as required. The ObjectList object can either embed the lists of objects or point to external URL(s) that hold such lists. ObjectList allows the specification of an object list type, providing instructions on the interpretation of the object list format. ObjectLists MAY be recursive, i.e. including references to secondary manifests, including references to HLS, MPEG-DASH or MSS manifests as well as additional JSON-encoded ObjectLists, etc. The party consuming the object list MUST parse all recursions based on the object list type property. When doing so, the consuming party should also detect potential loops when the descendant ObjectList points back to the parent ObjectList. Sopher, et al. Expires 24 April 2025 [Page 58] Internet-Draft CDN Interconnect Triggers October 2024 In the case of uCDN accessing ObjectList objects referencing external URLs published by dCDN, both parties should comply with the CI/T interface security requirements (see Section 8.1 for details). When dCDN accesses external URLs referenced by ObjectLists supplied by uCDN, for example as part of Trigger Spec, dCDN MUST match these URLs with source metadata objects, published by uCDN, such as SourceMetadata objects specified in Section 4.2.1 of [RFC8006], and use these metadata objects for content acquisition if a match was found. ObjectLists MAY combine regular objects and secondary ObjectLists in the same object. Please note that when embedding non-JSON object lists directly in ObjectList, absolute URLs MUST be provided at all times and the text SHOULD be encoded in accordance with the JSON grammar specification [ECMA404], including explicit newline encoding. When uCDN accesses ObjectList metadata resources published by uCDN, the same interface authentication and authorization requirements would apply, as when accessing the interface itself. ObjectList is encoded as an array of per-object records in JSON format as follows: External HLS manifest: [ { "href": "https://example.com/hls/a36f764e/index.m3u8", "type": "hls" } ] External object list in text format: [ { "href": "https://example.com/hls/35cdc008/assets", "type": "text" } ] List of external manifests and objects of mixed types: Sopher, et al. Expires 24 April 2025 [Page 59] Internet-Draft CDN Interconnect Triggers October 2024 [ { "href": "https://example.com/hls/35cdc008/index.m3u8", "type": "hls" }, { "href": "https://example.com/dash/35cdc008/main.mpd", "type": "dash" }, { "href": "https://example.com/dash/35cdc008/files.json", "type": "json" } ] Embedded JSON-encoded object list: [ { "data": [ { "href": "https://example.com/hls/35cdc008/index.m3u8", "type": "hls" }, { "href": "https://example.com/dash/35cdc008/main.mpd", "type": "dash" }, { "href": "https://example.com/img/35cdc008/thumb-l.jpg", "size": 10260 }, { "href": "https://example.com/img/35cdc008/thumb-s.jpg", "size": 1453 } ], "type": "json" } ] Embedded HLS manifest: Please note that some lines in the example are wrapped for clarity. Sopher, et al. Expires 24 April 2025 [Page 60] Internet-Draft CDN Interconnect Triggers October 2024 [ { "data": "#EXTM3U\n #EXT-X-STREAM-INF:BANDWIDTH=150000,RESOLUTION=416x234, CODECS=\"avc1.42e00a,mp4a.40.2\"\n http://example.com/low/index.m3u8\n #EXT-X-STREAM-INF:BANDWIDTH=240000,RESOLUTION=416x234, CODECS=\"avc1.42e00a,mp4a.40.2\"\n http://example.com/lo_mid/index.m3u8\n #EXT-X-STREAM-INF:BANDWIDTH=440000,RESOLUTION=416x234, CODECS=\"avc1.42e00a,mp4a.40.2\"\n http://example.com/hi_mid/index.m3u8\n #EXT-X-STREAM-INF:BANDWIDTH=640000,RESOLUTION=640x360, CODECS=\"avc1.42e00a,mp4a.40.2\"\n http://example.com/high/index.m3u8\n #EXT-X-STREAM-INF:BANDWIDTH=64000, CODECS=\"mp4a.40.5\"\n http://example.com/high/index.m3u8\n", "type": "hls" } ] The ObjectList properties are as follows: Name: data Description: List of objects in one of the recognized formats. Value: JSON String. Mandatory: No. Either "data" or "href" MUST be set. Name: href Description: URL pointing to an external object list or object in one of the recognized formats. Value: A URL represented as a JSON String Mandatory: No. Either "data" or "href" MUST be set. Name: type Description: Object list type to be used when parsing and interpreting this object list. By default, each record in the list is assumed to represent an object that does not require additional processing. Value: ObjectListType (see Section 4.3.2). Mandatory: Yes. Sopher, et al. Expires 24 April 2025 [Page 61] Internet-Draft CDN Interconnect Triggers October 2024 4.3.2.1. ObjectList Type ObjectListType objects are used to specify the registered type of ObjectList objects (see Section 7.5), used in trigger spec, trigger objects and Error.v2 Description objects. The following table defines the initial ObjectListType JSON string values +========+==================+===============+===============+ | JSON | Description | Specification | Protocol | | string | | | Specification | +========+==================+===============+===============+ | hls | HTTP Live | RFCthis | RFC 8216 | | | Streaming | | [RFC8216] | +--------+------------------+---------------+---------------+ | mss | Microsoft Smooth | RFCthis | MSS [MSS] | | | Streaming | | | +--------+------------------+---------------+---------------+ | dash | Dynamic Adaptive | RFCthis | MPEG-DASH | | | Streaming over | | [MPEG-DASH] | | | HTTP (MPEG-DASH) | | | +--------+------------------+---------------+---------------+ | json | JSON-serialized | RFCthis | JSON (Section | | | object list | | 4.3.2.2) | +--------+------------------+---------------+---------------+ | text | Object list in | RFCthis | Text (Section | | | text format | | 4.3.2.3) | +--------+------------------+---------------+---------------+ Table 10 [RFC Editor: Please replace RFCthis with the published RFC number for this document.] 4.3.2.2. JSON Serialized Object List This ObjectList type specifies a collection of objects encoded in JSON format, where each entry is encoded as an ObjectEntry (Section 4.3.2.4) object. The entries in the JSON object list MAY have an object list type specified, allowing for a recursive object list structure. Sopher, et al. Expires 24 April 2025 [Page 62] Internet-Draft CDN Interconnect Triggers October 2024 4.3.2.3. Text Object List Unlike the JSON Serialized Object List (Section 4.3.2.2), the text- based object list will not support a recursive object list structure and every object specified in it SHOULD be downloaded without additional processing. 4.3.2.4. ObjectEntry ObjectEntry is a metadata object describing an object and its associated metadata, to be used in JSON-encoded ObjectList (Section 4.3.2) objects. The following is an example of JSON-serialized ObjectEntry objects: [ { "href": "https://example.com/hls/35cdc008/index.m3u8", "type": "hls" }, { "href": "https://example.com/dash/35cdc008/main.mpd", "type": "dash" }, { "href": "https://example.com/img/35cdc008/thumb-l.jpg", "size": 102600 }, { "href": "https://example.com/img/35cdc008/thumb-s.jpg", "size": 14535 } ] The ObjectEntry properties are as follows: Name: href Description: Object URL Value: A URL represented as a JSON string. Mandatory: Yes. Name: type Description: ObjectList type to be used when processing this object. By default, ObjectEntry object is assumed to represent an object and does not require additional processing. Sopher, et al. Expires 24 April 2025 [Page 63] Internet-Draft CDN Interconnect Triggers October 2024 Value: ObjectListType (see Section 4.3.2.1). Mandatory: No. Name: size Description: Object size, in bytes. Can be used to decide to download the object based on size. For example, dCDN may ignore objects that are too small or too large. Value: Integer. Mandatory: No. 4.3.3. CDN Provider ID The CDN PID consists of the two characters "AS" followed by the CDN provider's Autonomous System number [RFC1930], then a colon (":") and an additional qualifier that is used to guarantee uniqueness in case a particular AS has multiple independent CDNs deployed -- for example, "AS64496:0". If the CDN provider has multiple ASes, the same AS number SHOULD be used in all messages from that CDN provider, unless there are multiple distinct CDNs. If the CDNI Request Routing Redirection interface (RI) described in [RFC7975] is implemented by dCDN, the CI/T interface and the RI SHOULD use the same CDN PID. 5. Footprint and Capabilities This section covers the FCI objects required for the advertisement of the specs, extensions, and properties introduced in this document. 5.1. CI/T Endpoint Capability Object The CI/T trigger endpoint capability object is used to advertise one or more CI/T interface endpoints along with CI/T interface versions supported by these endpoints. The capability type is "FCI.CITEndpoints". Version 1, as originally defined in [RFC8007], is the default if this capability is not explicitly declared. A CI/T Endpoints capability object is encoded as an array of JSON objects containing the following name/value pairs: Name: trigger-endpoint-uri Description: CI/T endpoint URI Sopher, et al. Expires 24 April 2025 [Page 64] Internet-Draft CDN Interconnect Triggers October 2024 Value: A URL represented as a JSON string. Mandatory: Yes. Name: trigger-versions Description: A list of CI/T versions supported by the trigger endpoint. Value: An array of JSON strings. Mandatory: Yes. Name: trigger-subject Description: Array of trigger subjects supported by the trigger endpoint. Value: An array of Strings containing the type of the subject matching the generic-trigger-spec-value property, such as "content" or "metadata" as defined in Section 4.1.2.2. Mandatory: No. A missing or empty "trigger-subject" list means that all trigger subjects are supported by the endpoint. dCDN SHOULD advertise only one endpoint for every trigger subject and CI/T interface version pair. If more than one interface endpoint supports the same trigger subject and CI/T interface version (e.g. CI/T version 2 interface for content objects), uCDN SHOULD be able to use any of the advertised CI/T interface endpoints interchangeably. 5.1.1. CI/T Endpoints Capability Object Serialization The following shows an example of CI/T Endpoints Capability object serialization for dCDN that supports versions 2 and 2.1 of the CI/T interface. Sopher, et al. Expires 24 April 2025 [Page 65] Internet-Draft CDN Interconnect Triggers October 2024 { "capabilities": [ { "capability-type": "FCI.CITEndpoints", "capability-value": { "trigger-endpoint-uri": "https://dcdn.example.com/configuration/", "trigger-versions": [ "1" ], "trigger-subjects": "metadata" }, "footprints": { "footprint-type": "countrycode", "footprint-value": [ "us" ] } }, { "capability-type": "FCI.CITEndpoints", "capability-value": { "trigger-endpoint-uri": "https://dcdn.example.com/cache-management/", "trigger-versions": [ "2", "2.1" ], "trigger-subjects": "content" }, "footprints": { "footprint-type": "countrycode", "footprint-value": [ "us" ] } } ] } 5.2. CI/T Trigger Scope Capability Object The CI/T supports several trigger actions for different trigger subjects as defined in Section 4.1.1 and Section 4.1.2.2. Additional actions, as well as subjects, may be defined in the future. The Trigger Scope capability object is used to indicate support for a Trigger Action for a subject. It further specifies the Trigger Generic Spec types that may be used for selecting the targets the triggers are applied on, along with the supported Trigger Generic Extension types. The "trigger-scope-capability" object matches the "FCI.CITScope" capability type and is encoded as a JSON object containing the following name/value pairs: Name: trigger-action Description: The supported CDNI CI/T Trigger Action. Sopher, et al. Expires 24 April 2025 [Page 66] Internet-Draft CDN Interconnect Triggers October 2024 Value: A string corresponding to an entry from the "CDNI CI/T Trigger Types" registry Section 7.2, which corresponds to a CDNI CI/T Trigger Action. Mandatory: Yes. Name: trigger-subject Description: The supported CDNI CI/T Trigger Subject. Value: A string corresponding to an entry from the "CDNI CI/T Trigger Subjects" registry Section 7.4, which corresponds to a CDNI CI/T Trigger Subject. Mandatory: Yes. Name: trigger-specs Description: A list of supported CDNI CI/T GenericSpecObject types for Trigger Action and Subject. Value: List of strings corresponding to entries from the "CDNI CI/T Trigger Specs" registry Section 7.3, which correspond to CDNI CI/T GenericSpecObject objects. Mandatory: No. The default, in case of a missing or an empty list, MUST be interpreted as "no GenericExtensionObject types are supported". A non-empty list MUST be interpreted as containing "the only GenericExtensionObject types that are supported". Name: trigger-extensions Description: A list of supported CDNI CI/T GenericExtensionObject types for Trigger Action and Subject. Value: List of strings corresponding to entries from the "CDNI CI/T Trigger Extension" registry Section 7.6, which corresponds to a CDNI CI/T GenericExtensionObject object. Mandatory: No. The default, in case of a missing or an empty list, MUST be interpreted as "no GenericExtensionObject types are supported". A non-empty list MUST be interpreted as containing "the only GenericExtensionObject types that are supported". Sopher, et al. Expires 24 April 2025 [Page 67] Internet-Draft CDN Interconnect Triggers October 2024 5.2.1. CI/T Trigger Scope Capability Object Serialization The following shows an example of a JSON-serialized CI/T Trigger Scope Capability object serialization for dCDN that supports the preposition and invalidation of content, using "urls" and "ccids" Generic Spec types, with "time-policy" but only for the "preposition" action. Note that in this example, purge is not supported, and no actions involving metadata are supported either. { "capabilities": [{ "capability-type": "FCI.CITScope", "capability-value": { "trigger-scope-capabilities": [ { "trigger-action": "preposition", "trigger-subject": "content", "trigger-specs": [ "urls", "ccids" ], "trigger-extensions": [ "time-policy" ] }, { "trigger-action": "invalidate", "trigger-subject": "content", "trigger-specs": [ "urls", "ccids" ] } ] }, "footprints": { "footprint-type": "countrycode", "footprint-value": [ "us" ] } }] } 5.3. CI/T Object List Type Capability Object Given an object list being supported by dCDN, the CI/T Object List Type capability object is used to indicate support for one or more Object List types listed in Section 7.5 by the type property of the "ObjectList" object. The capability type is "FCI.CITObjectListType". Name: object-list-types Description: A list of supported ObjectList types. Value: An array of Section 4.3.2.1. Mandatory: No. In case of a missing or an empty list, MUST be interpreted as no ObjectList types are supported. Sopher, et al. Expires 24 April 2025 [Page 68] Internet-Draft CDN Interconnect Triggers October 2024 5.3.1. CI/T Object List Type Capability Object Serialization The following shows an example of a JSON-serialized CI/T Object List Type Capability object serialization for dCDN that supports "hls" and "dash". { "capabilities": [{ "capability-type": "FCI.CITObjectListType", "capability-value": { "object-list-types": [ "hls", "dash", "json" ] }, "footprints": { "footprint-type": "countrycode", "footprint-value": [ "us" ] } }] } 5.4. CI/T Private URL Capability Object The CI/T Private URL capability object is used to indicate support for operations on private URLs (see Section 4.3.1 for details). The capability type is "FCI.CITPrivateUrlType". Name: private-url-type-support Description: Indicate whether private URL type is supported by dCDN. Value: Boolean. Mandatory: No. In case of missing or an empty attribute, MUST be interpreted as no support for private URLs. 5.4.1. CI/T Private URL Type Capability Object Serialization The following shows an example of a JSON-serialized CI/T Private URL Type Capability object serialization for dCDN that supports the private URL type in URL-based trigger spec types. Sopher, et al. Expires 24 April 2025 [Page 69] Internet-Draft CDN Interconnect Triggers October 2024 { "capabilities": [{ "capability-type": "FCI.CITPrivateUrlType", "capability-value": { "private-url-type-support": true }, "footprints": { "footprint-type": "countrycode", "footprint-value": [ "us" ] } }] } 5.5. CI/T Extended Status Capability Object CI/T Extended Trigger Status Capability object is used to indicate support for extended trigger status. The extended trigger status is returned upon uCDN request and includes: * "objects" attribute in top-level Trigger object * "objects" attribute in Error.v2 Description object * "all-triggers" attribute in top-level Trigger Collections object The capability type is "FCI.CITExtendedStatus". Name: extended-status-objects Description: List of CI/T objects that support extended attributes. Value: An array of JSON strings listing CI/T objects. Mandatory: No. By default, in case of a missing or an empty list, no extended attribute objects are supported. 5.5.1. CI/T Private URL Type Capability Object Serialization The following shows an example of a JSON-serialized CI/T Extended Status Type Capability object serialization for dCDN that supports extended status in Trigger, Error.v2 Description and Trigger Collections objects. Sopher, et al. Expires 24 April 2025 [Page 70] Internet-Draft CDN Interconnect Triggers October 2024 { "capabilities": [{ "capability-type": "FCI.CITExtendedStatus", "capability-value": { "extended-status-objects": [ "trigger-state" , "error-v2-description", "trigger-collection" ] }, "footprints": { "footprint-type": "countrycode", "footprint-value": [ "us" ] } }] } 6. Examples The following subsections provide examples of different CI/T objects encoded as JSON. The discovery of the CI/T interface is out of scope of this document. In an implementation, all CI/T URLs are under the control of the dCDN. uCDN MUST NOT attempt to ascribe any meaning to individual elements of the path. In examples in this section, the URL "https://dcdn.example.com/ triggers" is used as the location of the collection of all Trigger Status Resources, and the CDN PID of uCDN is "AS64496:1". 6.1. Creating Triggers Examples of uCDN triggering activity in dCDN: 6.1.1. Preposition Below is an example of a "preposition" trigger -- a POST to the collection of all triggers. Note that pattern-based specs like "UriPatternMatch" and "UrisRegexMatch" are not allowed in a preposition Trigger Specification, where dCDN has to have a clear list of objects to obtain. Sopher, et al. Expires 24 April 2025 [Page 71] Internet-Draft CDN Interconnect Triggers October 2024 REQUEST: POST /triggers HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* Content-Type: application/cdni; ptype=ci-trigger.v2 Content-Length: 352 { "action": "preposition", "specs": [ { "trigger-subject": "metadata", "generic-trigger-spec-type": "urls", "generic-trigger-spec-value": { "urls": [ "https://metadata.example.com/a/b/c" ] } }, { "trigger-subject": "content", "generic-trigger-spec-type": "urls", "generic-trigger-spec-value": { "urls": [ "https://www.example.com/a/b/c/1", "https://www.example.com/a/b/c/2", "https://www.example.com/a/b/c/3", "https://www.example.com/a/b/c/4" ] } } ], "cdn-path": [ "AS64496:1" ] } RESPONSE: HTTP/1.1 201 Created Date: Wed, 04 May 2016 08:48:10 GMT Content-Length: 467 Content-Type: application/cdni; ptype=ci-trigger.v2 Location: https://dcdn.example.com/triggers/0 Server: example-server/0.1 { "ctime": 1462351690, "etime": 1462351698, Sopher, et al. Expires 24 April 2025 [Page 72] Internet-Draft CDN Interconnect Triggers October 2024 "mtime": 1462351690, "state": "pending", "action": "preposition", "specs": [ { "trigger-subject": "metadata", "generic-trigger-spec-type": "urls", "generic-trigger-spec-value": { "urls": [ "https://metadata.example.com/a/b/c" ] } }, { "trigger-subject": "content", "generic-trigger-spec-type": "urls", "generic-trigger-spec-value": { "urls": [ "https://www.example.com/a/b/c/1", "https://www.example.com/a/b/c/2", "https://www.example.com/a/b/c/3", "https://www.example.com/a/b/c/4" ] } } ], "cdn-path": [ "AS64496:1" ] } 6.1.2. Invalidate Below is an example of a CI/T "invalidate" trigger -- another POST to the collection of all triggers. This instructs the dCDN to revalidate the content at "https://www.example.com/a/index.html", as well as any metadata and content whose URLs are prefixed by "https://metadata.example.com/a/b/" using case-insensitive matching, and "https://www.example.com/a/b/" using case-sensitive matching, respectively. REQUEST: POST /triggers HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* Content-Type: application/cdni; ptype=ci-trigger.v2 Content-Length: 387 { "action": "invalidate", Sopher, et al. Expires 24 April 2025 [Page 73] Internet-Draft CDN Interconnect Triggers October 2024 "specs": [ { "trigger-subject": "metadata", "generic-trigger-spec-type": "uri-pattern-match", "generic-trigger-spec-value": { "pattern": "https://metadata.example.com/a/b/*" } }, { "trigger-subject": "content", "generic-trigger-spec-type": "urls", "generic-trigger-spec-value": { "urls": [ "https://www.example.com/a/index.html" ] } }, { "trigger-subject": "content", "generic-trigger-spec-type": "uri-pattern-match", "generic-trigger-spec-value": { "pattern": "https://www.example.com/a/b/*", "case-sensitive": true } } ], "cdn-path": [ "AS64496:1" ] } RESPONSE: HTTP/1.1 201 Created Date: Wed, 04 May 2016 08:48:11 GMT Content-Length: 545 Content-Type: application/cdni; ptype=ci-trigger.v2 Location: https://dcdn.example.com/triggers/1 Server: example-server/0.1 { "ctime": 1462351691, "etime": 1462351699, "mtime": 1462351691, "state": "pending", "action": "invalidate", "specs": [ { "trigger-subject": "metadata", "generic-trigger-spec-type": "uri-pattern-match", Sopher, et al. Expires 24 April 2025 [Page 74] Internet-Draft CDN Interconnect Triggers October 2024 "generic-trigger-spec-value": { "pattern": "https://metadata.example.com/a/b/*" } }, { "trigger-subject": "content", "generic-trigger-spec-type": "urls", "generic-trigger-spec-value": { "urls": [ "https://www.example.com/a/index.html" ] } }, { "trigger-subject": "content", "generic-trigger-spec-type": "uri-pattern-match", "generic-trigger-spec-value": { "pattern": "https://www.example.com/a/b/*", "case-sensitive": true } } ], "cdn-path": [ "AS64496:1" ] } 6.1.3. Invalidation with Regex In the following example, a CI/T "invalidate" trigger uses the Regex property to specify the range of content objects for invalidation, the trigger is rejected by dCDN due to regex complexity, and an appropriate error is reflected in the response. Please note that some lines in the example are wrapped for clarity. REQUEST: POST /triggers HTTP/1.1 User-Agent: example-user-agent/0.1 Host: triggers.dcdn.example.com Accept: */* Content-Type: application/cdni; ptype=ci-trigger.v2 { "action": "invalidate", "specs": [{ "trigger-subject": "content", "generic-trigger-spec-type": "uri-regex-match", "generic-trigger-spec-value": { "regex": "^(https:\\/\\/video\\.example\\.com)\\/ ([a-z])\\/movie1\\/([1-7])\\/*(index.m3u8|\\d{3}.ts)$", Sopher, et al. Expires 24 April 2025 [Page 75] Internet-Draft CDN Interconnect Triggers October 2024 "case-sensitive": true, "match-query-string": false } }], "cdn-path": [ "AS64496:0" ] } RESPONSE: HTTP/1.1 201 Created Date: Wed, 04 May 2016 08:48:10 GMT Content-Length: 467 Content-Type: application/cdni; ptype=ci-trigger.v2 Location: https://triggers.dcdn.example.com/triggers/2 Server: example-server/0.1 { "errors": [{ "specs": [{ "trigger-subject": "content", "generic-trigger-spec-type": "uri-regex-match", "generic-trigger-spec-value": { "regex": "^(https:\\/\\/video\\.example\\.com)\\/([a-z])\ \/movie1\\/([1-7])\\/*(index.m3u8|\\d{3}.ts)$", "case-sensitive": true, "match-query-string": false } }], "description": "dCDN rejected a regex due to complexity", "error": "ereject", "cdn": "AS64500:0" }], "ctime": 1462351690, "etime": 1462351698, "mtime": 1462351690, "state": "failed", "action": "invalidate", "specs": [{ "trigger-subject": "content", "generic-trigger-spec-type": "uri-regex-match", "generic-trigger-spec-value": { "regex": "^(https:\\/\\/video\\.example\\.com)\\/([a-z])\ \/movie1\\/([1-7])\\/*(index.m3u8|\\d{3}.ts)$", "case-sensitive": true, "match-query-string": false } }], "cdn-path": [ "AS64496:0" ] Sopher, et al. Expires 24 April 2025 [Page 76] Internet-Draft CDN Interconnect Triggers October 2024 } 6.1.4. Preposition with ObjectLists In the following example, a CI/T "preposition" trigger uses the ObjectList property to specify the full media library of a specific content. The command fails due to object list parse error and an appropriate error is reflected in the status response. REQUEST: POST /triggers HTTP/1.1 User-Agent: example-user-agent/0.1 Host: triggers.dcdn.example.com Accept: */* Content-Type: application/cdni; ptype=ci-trigger.v2 { "action": "preposition", "specs": [{ "trigger-subject": "content", "generic-trigger-spec-type": "content-objectlist", "generic-trigger-spec-value": { "objects": [{ "href": "https://www.example.com/hls/title/index.m3u8", "type": "hls" }] } }], "cdn-path": [ "AS64496:0" ] } RESPONSE: HTTP/1.1 201 Created Date: Wed, 04 May 2016 08:48:10 GMT Content-Length: 467 Content-Type: application/cdni; ptype=ci-trigger.v2 Location: https://triggers.dcdn.example.com/triggers/3 Server: example-server/0.1 { "errors": [{ "specs": [{ "trigger-subject": "content", "generic-trigger-spec-type": "content-objectlist", "generic-trigger-spec-value": { "objects": [{ Sopher, et al. Expires 24 April 2025 [Page 77] Internet-Draft CDN Interconnect Triggers October 2024 "href": "https://www.example.com/hls/title/index.m3u8", "type": "hls" }} }], "description": "dCDN was not able to parse the object list", "error": "econtent", "cdn": "AS64500:0" }], "ctime": 1462351690, "etime": 1462351698, "mtime": 1462351690, "state": "failed", "action": "preposition", "specs": [{ "trigger-subject": "content", "generic-trigger-spec-type": "content-objectlist", "generic-trigger-spec-value": { "objects": [{ "href": "https://www.example.com/hls/title/index.m3u8", "type": "hls" }] } }], "cdn-path": [ "AS64496:0" ] } 6.2. Examining Trigger Status Once triggers have been created, uCDN can check their status as shown in the following examples. 6.2.1. Collection of All Triggers uCDN can fetch the collection of all triggers it has created that have not yet been deleted or expired. After the creation of the "preposition" and "invalidate" triggers shown above, this collection might look as follows: REQUEST: GET /triggers HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* RESPONSE: HTTP/1.1 200 OK Sopher, et al. Expires 24 April 2025 [Page 78] Internet-Draft CDN Interconnect Triggers October 2024 Content-Length: 341 Expires: Wed, 04 May 2016 08:49:11 GMT Server: example-server/0.1 ETag: "-936094426920308378" Cache-Control: max-age=60 Date: Wed, 04 May 2016 08:48:11 GMT Content-Type: application/cdni; ptype=ci-trigger-collection { "cdn-id": "AS64496:0", "coll-status": [ { "status" : "pending", "collection": "/triggers/pending" }, { "status" : "active", "collection": "/triggers/active" }, { "status" : "complete", "collection": "/triggers/complete" }, { "status" : "processed", "collection": "/triggers/processed" }, { "status" : "failed", "collection": "/triggers/failed" }, { "status" : "cancelling", "collection": "/triggers/cancelling" }, { "status" : "cancelled", "collection": "/triggers/cancelled" } ], "coll-label": [ { "label" : "1b1bad0c", "collection": "/triggers/1b1bad0c" }, { "label" : "fafa9a97", "collection": "/triggers/fafa9a97" Sopher, et al. Expires 24 April 2025 [Page 79] Internet-Draft CDN Interconnect Triggers October 2024 } ], "staleresourcetime": 86400, "triggers": [ "https://dcdn.example.com/triggers/0", "https://dcdn.example.com/triggers/1" ] } 6.2.2. Filtered Collections of Triggers The filtered collections are also available to uCDN. Before the dCDN starts processing the two triggers shown above, both will appear in the collection of pending triggers. For example: REQUEST: GET /triggers/pending HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* RESPONSE: HTTP/1.1 200 OK Content-Length: 152 Expires: Wed, 04 May 2016 08:49:11 GMT Server: example-server/0.1 ETag: "4331492443626270781" Cache-Control: max-age=60 Date: Wed, 04 May 2016 08:48:11 GMT Content-Type: application/cdni; ptype=ci-trigger-collection { "staleresourcetime": 86400, "triggers": [ "https://dcdn.example.com/triggers/0", "https://dcdn.example.com/triggers/1" ] } At this point, if no other triggers had been created, the other filtered views would be empty. For example: Sopher, et al. Expires 24 April 2025 [Page 80] Internet-Draft CDN Interconnect Triggers October 2024 REQUEST: GET /triggers/complete HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* RESPONSE: HTTP/1.1 200 OK Content-Length: 54 Expires: Wed, 04 May 2016 08:49:11 GMT Server: example-server/0.1 ETag: "7958041393922269003" Cache-Control: max-age=60 Date: Wed, 04 May 2016 08:48:11 GMT Content-Type: application/cdni; ptype=ci-trigger-collection { "staleresourcetime": 86400, "triggers": [] } 6.2.3. Individual Trigger Resources uCDN can also examine individual triggers. For example, for the "preposition" and "invalidate" triggers from previous examples: REQUEST: GET /triggers/0 HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* RESPONSE: HTTP/1.1 200 OK Content-Length: 467 Expires: Wed, 04 May 2016 08:49:10 GMT Server: example-server/0.1 ETag: "6990548174277557683" Cache-Control: max-age=60 Date: Wed, 04 May 2016 08:48:10 GMT Content-Type: application/cdni; ptype=ci-trigger.v2 { "ctime": 1462351690, Sopher, et al. Expires 24 April 2025 [Page 81] Internet-Draft CDN Interconnect Triggers October 2024 "etime": 1462351698, "mtime": 1462351690, "status": "pending", "action": "preposition", "specs": [ { "trigger-subject": "metadata", "generic-trigger-spec-type": "urls", "generic-trigger-spec-value": { "urls": [ "https://metadata.example.com/a/b/c" ] } }, { "trigger-subject": "content", "generic-trigger-spec-type": "urls", "generic-trigger-spec-value": { "urls": [ "https://www.example.com/a/b/c/1", "https://www.example.com/a/b/c/2", "https://www.example.com/a/b/c/3", "https://www.example.com/a/b/c/4" ] } } ] } REQUEST: GET /triggers/1 HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* RESPONSE: HTTP/1.1 200 OK Content-Length: 545 Expires: Wed, 04 May 2016 08:49:11 GMT Server: example-server/0.1 ETag: "-554385204989405469" Cache-Control: max-age=60 Date: Wed, 04 May 2016 08:48:11 GMT Content-Type: application/cdni; ptype=ci-trigger.v2 { "ctime": 1462351691, "etime": 1462351699, Sopher, et al. Expires 24 April 2025 [Page 82] Internet-Draft CDN Interconnect Triggers October 2024 "mtime": 1462351691, "status": "pending", "action": "invalidate", "specs": [ { "trigger-subject": "metadata", "generic-trigger-spec-type": "uri-pattern-match", "generic-trigger-spec-value": { "pattern": "https://metadata.example.com/a/b/*" } }, { "trigger-subject": "content", "generic-trigger-spec-type": "urls", "generic-trigger-spec-value": { "urls": [ "https://www.example.com/a/index.html" ] } }, { "trigger-subject": "content", "generic-trigger-spec-type": "uri-pattern-match", "generic-trigger-spec-value": { "pattern": "https://www.example.com/a/b/*", "case-sensitive": true } } ] } 6.2.4. Polling for Changes in Status uCDN SHOULD use the ETags of collections or triggers when polling for changes in status, as shown in the following examples: Sopher, et al. Expires 24 April 2025 [Page 83] Internet-Draft CDN Interconnect Triggers October 2024 REQUEST: GET /triggers/pending HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* If-None-Match: "4331492443626270781" RESPONSE: HTTP/1.1 304 Not Modified Content-Length: 0 Expires: Wed, 04 May 2016 08:49:11 GMT Server: example-server/0.1 ETag: "4331492443626270781" Cache-Control: max-age=60 Date: Wed, 04 May 2016 08:48:11 GMT Content-Type: application/cdni; ptype=ci-trigger-collection REQUEST: GET /triggers/0 HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* If-None-Match: "6990548174277557683" RESPONSE: HTTP/1.1 304 Not Modified Content-Length: 0 Expires: Wed, 04 May 2016 08:49:10 GMT Server: example-server/0.1 ETag: "6990548174277557683" Cache-Control: max-age=60 Date: Wed, 04 May 2016 08:48:10 GMT Content-Type: application/cdni; ptype=ci-trigger.v2 When the trigger processing is complete, the contents of the filtered collections will be updated along with their ETags. For example, when the two example triggers are complete, the collections of pending and complete triggers look as follows: REQUEST: GET /triggers/pending HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* Sopher, et al. Expires 24 April 2025 [Page 84] Internet-Draft CDN Interconnect Triggers October 2024 RESPONSE: HTTP/1.1 200 OK Content-Length: 54 Expires: Wed, 04 May 2016 08:49:15 GMT Server: example-server/0.1 ETag: "1337503181677633762" Cache-Control: max-age=60 Date: Wed, 04 May 2016 08:48:15 GMT Content-Type: application/cdni; ptype=ci-trigger-collection { "staleresourcetime": 86400, "triggers": [] } REQUEST: GET /triggers/complete HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* RESPONSE: HTTP/1.1 200 OK Content-Length: 152 Expires: Wed, 04 May 2016 08:49:22 GMT Server: example-server/0.1 ETag: "4481489539378529796" Cache-Control: max-age=60 Date: Wed, 04 May 2016 08:48:22 GMT Content-Type: application/cdni; ptype=ci-trigger-collection { "staleresourcetime": 86400, "triggers": [ "https://dcdn.example.com/triggers/0", "https://dcdn.example.com/triggers/1" ] } 6.2.5. Deleting Triggers uCDN can delete completed and failed triggers to reduce the size of the collections, as described in Section 3.5. For example, to delete the "preposition" trigger from earlier examples: Sopher, et al. Expires 24 April 2025 [Page 85] Internet-Draft CDN Interconnect Triggers October 2024 REQUEST: DELETE /triggers/0 HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* RESPONSE: HTTP/1.1 204 No Content Date: Wed, 04 May 2016 08:48:22 GMT Content-Length: 0 Content-Type: text/html; charset=UTF-8 Server: example-server/0.1 This would, for example, cause the collection of completed Trigger Status Resources shown in the example above, to be updated to: REQUEST: GET /triggers/complete HTTP/1.1 User-Agent: example-user-agent/0.1 Host: dcdn.example.com Accept: */* RESPONSE: HTTP/1.1 200 OK Content-Length: 105 Expires: Wed, 04 May 2016 08:49:22 GMT Server: example-server/0.1 ETag: "-6938620031669085677" Cache-Control: max-age=60 Date: Wed, 04 May 2016 08:48:22 GMT Content-Type: application/cdni; ptype=ci-trigger-collection { "staleresourcetime": 86400, "triggers": [ "https://dcdn.example.com/triggers/1" ] } Sopher, et al. Expires 24 April 2025 [Page 86] Internet-Draft CDN Interconnect Triggers October 2024 6.2.6. Extensions with Error Propagation In the following example, a CI/T "preposition" command is using two extensions to control the way the trigger is executed. In this example, the receiving dCDN, identified as "AS64500:0", does not support the first extension in the extensions array. dCDN "AS64500:0" further distributes this trigger to another downstream CDN that is identified as "AS64501:0", which does not support the second extension in the extensions array. The error is propagated from "AS64501:0" to "AS64500:0" and the errors.v2 array reflects both errors. REQUEST: POST /triggers HTTP/1.1 User-Agent: example-user-agent/0.1 Host: triggers.dcdn.example.com Accept: */* Content-Type: application/cdni; ptype=ci-trigger.v2 { "action": "preposition", "specs": [{ "trigger-subject": "content", "generic-trigger-spec-type": "content-objectlist", "generic-trigger-spec-value": { "objects": [{ "href": "https://www.example.com/hls/title/index.m3u8", "type": "hls" }] } }], "extensions": [ { "generic-trigger-extension-type": "location-policy", "generic-trigger-extension-value": { "locations": [ { "action": "allow", "footprints": [{ "footprint-type": "countrycode", "footprint-value": [ "us" ] }] }, { "action": "deny", "footprints": [{ "footprint-type": "countrycode", Sopher, et al. Expires 24 April 2025 [Page 87] Internet-Draft CDN Interconnect Triggers October 2024 "footprint-value": [ "ca" ] }] } ] }, "mandatory-to-enforce": true, "safe-to-redistribute": true }, { "generic-trigger-extension-type": "time-policy", "generic-trigger-extension-value": { "unix-time-window": { "start": 946717200, "end": 946746000 } }, "mandatory-to-enforce": true, "safe-to-redistribute": true } ], "cdn-path": [ "AS64496:0" ] } RESPONSE: HTTP/1.1 201 Created Date: Wed, 04 May 2016 08:48:10 GMT Content-Length: 467 Content-Type: application/cdni; ptype=ci-trigger.v2 Location: https://triggers.dcdn.example.com/triggers/0 Server: example-server/0.1 { "errors": [ { "extensions": [{ "generic-trigger-extension-type": "location-policy", "generic-trigger-extension-value": { "locations": [ { "action": "allow", "footprints": [{ "footprint-type": "countrycode", "footprint-value": [ "us" ] }] }, { "action": "deny", Sopher, et al. Expires 24 April 2025 [Page 88] Internet-Draft CDN Interconnect Triggers October 2024 "footprints": [{ "footprint-type": "countrycode", "footprint-value": [ "ca" ] }] } ] }, "mandatory-to-enforce": true, "safe-to-redistribute": true }], "description": "unrecognized extension type", "error": "eextension", "cdn": "AS64500:0" }, { "extensions": [{ "generic-trigger-extension-type": "time-policy", "generic-trigger-extension-value": { "unix-time-window": { "start": 946717200, "end": 946746000 } }, "mandatory-to-enforce": true, "safe-to-redistribute": true }], "description": "unrecognized extension type", "error": "eextension", "cdn": "AS64501:0" } ], "ctime": 1462351690, "etime": 1462351698, "mtime": 1462351690, "status": "failed", "action": "preposition", "specs": [{ "trigger-subject": "content", "generic-trigger-spec-type": "content-objectlist", "generic-trigger-spec-value": { "objects": [{ "href": "https://www.example.com/hls/title/index.m3u8", "type": "hls" }] } }], "extensions": [ { Sopher, et al. Expires 24 April 2025 [Page 89] Internet-Draft CDN Interconnect Triggers October 2024 "generic-trigger-extension-type": "location-policy", "generic-trigger-extension-value": { "locations": [ { "action": "allow", "footprints": [{ "footprint-type": "countrycode", "footprint-value": [ "us" ] }] }, { "action": "deny", "footprints": [{ "footprint-type": "countrycode", "footprint-value": [ "ca" ] }] } ] }, "mandatory-to-enforce": true, "safe-to-redistribute": true }, { "generic-trigger-extension-type": "time-policy", "generic-trigger-extension-value": { "unix-time-window": { "start": 946717200, "end": 946746000 } }, "mandatory-to-enforce": true, "safe-to-redistribute": true } ], "cdn-path": [ "AS64496:0" ] } 7. IANA Considerations 7.1. CDNI Payload Type Parameter Registrations All references to RFC 8007 in the IANA registries should be replaced with references to this document, apart from references associated with the following registrations: Sopher, et al. Expires 24 April 2025 [Page 90] Internet-Draft CDN Interconnect Triggers October 2024 +=======================+===============+ | Payload Type | Specification | +=======================+===============+ | ci-trigger-command | RFC 8007 | +-----------------------+---------------+ | ci-trigger-status | RFC 8007 | +-----------------------+---------------+ | ci-trigger-collection | RFC 8007 | +-----------------------+---------------+ Table 11 The IANA is requested to register the following new Payload Types in the "CDNI Payload Types" registry defined by [RFC7736], for use with the "application/cdni" MIME media type. +=======================+===============+ | Payload Type | Specification | +=======================+===============+ | ci-trigger.v2 | RFCthis | +-----------------------+---------------+ | FCI.CITObjectsVersion | RFCthis | +-----------------------+---------------+ | FCI.CITScope | RFCthis | +-----------------------+---------------+ | FCI.CITObjectListType | RFCthis | +-----------------------+---------------+ Table 12 [RFC Editor: Please replace RFCthis with the published RFC number for this document.] 7.1.1. CDNI ci-trigger.v2 Payload Type Purpose: The purpose of this payload type is to define a new CI/T trigger object (and any associated capability advertisement) Interface: CI/T Encoding: see Section 4.1 7.1.2. CDNI FCI CI/T Payload Types 7.1.2.1. CDNI FCI CI/T Endpoints Payload Type Purpose: The purpose of this payload type is to distinguish FCI advertisement objects for CI/T Endpoints objects Sopher, et al. Expires 24 April 2025 [Page 91] Internet-Draft CDN Interconnect Triggers October 2024 Interface: FCI Encoding: see Section 5.1 7.1.2.2. CDNI FCI CI/T Trigger Scope Payload Type Purpose: The purpose of this payload type is to distinguish FCI advertisement objects for CI/T Trigger Scope Interface: FCI Encoding: see Section 5.2.1 7.1.2.3. CDNI FCI CI/T Object List Type Payload Type Purpose: The purpose of this payload type is to distinguish FCI advertisement objects for CI/T Object List Type objects Interface: FCI Encoding: see Section 5.3 7.2. "CDNI CI/T Trigger Types" Registry For Trigger Actions In [RFC8007] the IANA was requested to create a new "CDNI CI/T Trigger Types" registry under the "Content Delivery Network Interconnection (CDNI) Parameters" registry group. Additions to the "CDNI CI/T Trigger Types" registry are made via the RFC Required policy as defined in [RFC8126]. In this second edition of the interface, trigger types are referred to as "trigger actions". The "Trigger Types" registry is used for action definitions. Furthermore, this document, and specifically Section 4.1.1, reuses the definition of "trigger types" as defined in [RFC8007] as trigger actions, and provide their specifications, with no modification compared to [RFC8007]. 7.3. "CDNI CI/T Trigger Specs" Registry The IANA is requested to create a new "CDNI CI/T Trigger Specs" registry in the "Content Delivery Networks Interconnection (CDNI) Parameters" registry group. The "CDNI CI/T Trigger Specs" namespace defines the valid trigger targets' spec values in Section 4.1.2, used by the Trigger Spec object. Additions to the "CDNI CI/T Trigger Specs" registry are made via the RFC Required policy as defined in [RFC8126]. Sopher, et al. Expires 24 April 2025 [Page 92] Internet-Draft CDN Interconnect Triggers October 2024 The initial contents of the "CDNI CI/T Trigger Specs" registry comprise the names and descriptions listed in Section 4.1.2, with this document acting as the specification. 7.4. "CDNI CI/T Trigger Subjects" Registry The IANA is requested to create a new "CDNI CI/T Trigger Subjects" registry in the "Content Delivery Networks Interconnection (CDNI) Parameters" registry group. The "CDNI CI/T Trigger Subjects" namespace defines the valid trigger targets' subject values in Section 4.1.2.2, used by the Trigger Spec object. Additions to the "CDNI CI/T Trigger Subjects" registry are made via the RFC Required policy as defined in [RFC8126]. The initial contents of the "CDNI CI/T Trigger Subjects" registry comprise the names and descriptions listed in Section 4.1.2.2, with this document acting as the specification. 7.5. "CDNI CI/T Object List Types" Registry The IANA is requested to create a new "CDNI CI/T Object List Types" registry in the "Content Delivery Networks Interconnection (CDNI) Parameters" registry group. The "CDNI CI/T Object List Types" namespace defines the valid object list type values in Section 4.3.2.1, used by the Object List object. Additions to the "CDNI CI/T Object List Types" registry are made via the RFC Required policy as defined in [RFC8126]. The initial contents of the "CDNI CI/T Object List Types" registry comprise the names and descriptions listed in Section 4.3.2.1, with this document acting as the specification. 7.6. "CDNI CI/T Trigger Extensions" Registry The IANA is requested to create a new "CDNI CI/T Trigger Extensions" registry in the "Content Delivery Networks Interconnection (CDNI) Parameters" registry group. The "CDNI CI/T Trigger Extensions" namespace defines the valid trigger targets' extension values in Section 2.7, used by the Trigger Spec object. Additions to the "CDNI CI/T Trigger Extensions" registry are made via the RFC Required policy as defined in [RFC8126]. The initial contents of the "CDNI CI/T Trigger Extensions" registry comprise the names and descriptions listed in Section 2.7, with this document acting as the specification. Sopher, et al. Expires 24 April 2025 [Page 93] Internet-Draft CDN Interconnect Triggers October 2024 7.7. "CDNI CI/T Error Codes" Registry In [RFC8007] the IANA was requested to create a new "CDNI CI/T Error Codes" registry under the "Content Delivery Network Interconnection (CDNI) Parameters" registry group. Additions to the "CDNI CI/T Error Codes" registry are made via the Specification Required policy as defined in [RFC8126]. The Designated Expert will verify that new Error Code registrations do not duplicate existing Error Code definitions (in name or functionality), prevent gratuitous additions to the namespace, and prevent any additions to the namespace that would impair the interoperability of CDNI implementations. In this second edition of the interface, we list and repeat the definition of the Error Codes from [RFC8007] - acting as the entities specification with no modification compared to [RFC8007]. Additionally, the IANA is requested to register three additional error codes, "espec", "esubject" and "eextension", with specification as defined in Section 4.1.5.2. 7.8. "CDNI CI/T URL Types" Registry The IANA is requested to create a new "CDNI CI/T URL types" registry in the "Content Delivery Networks Interconnection (CDNI) Parameters" registry group. The "CDNI CI/T URL Types" namespace defines the valid URL type values in Section 4.3.1, used by Section 4.1.2.3, Section 4.1.2.5, Section 4.1.2.6 and Section 4.1.2.7. The initial contents of the "CDNI CI/T Trigger Extensions" registry comprise the names and descriptions listed in Section 4.3.1, with this document acting as the specification. 8. Security Considerations The CI/T interface provides a mechanism to allow uCDN to generate requests into dCDN and to inspect its own CI/T requests and their current states. The CI/T interface does not allow access to, or modification of, uCDN or dCDN metadata relating to content delivery or to the content itself. It can only control the presence of that metadata in dCDN, and the processing work and network utilization involved in ensuring that presence. By examining "preposition" requests to dCDN, and correctly interpreting content and metadata URLs, an attacker could learn the uCDN's or content owner's predictions for future content popularity. By examining "invalidate" or "purge" requests, an attacker could learn about changes in the content owner's catalog. Sopher, et al. Expires 24 April 2025 [Page 94] Internet-Draft CDN Interconnect Triggers October 2024 By injecting CI/T triggers, an attacker or a misbehaving uCDN would generate work in dCDN and uCDN as they process those requests. So would a man-in-the-middle attacker modify valid trigger requests generated by uCDN. In both cases, that would decrease dCDN's caching efficiency by causing it to unnecessarily acquire or reacquire content metadata and/or content. dCDN implementation of CI/T MUST restrict the actions of uCDN to the data corresponding to that uCDN. Failure to do so would allow uCDNs to detrimentally affect each other's efficiency by generating unnecessary acquisition or reacquisition load. An origin that chooses to delegate its delivery to a CDN is trusting that CDN to deliver content on its behalf; the interconnection of CDNs is an extension of that trust to dCDNs. That trust relationship is a commercial arrangement, outside the scope of the CDNI protocols. So, while a malicious CDN could deliberately generate load on dCDN using the CI/T interface, the protocol does not otherwise attempt to address malicious behavior between interconnected CDNs. 8.1. Authentication, Authorization, Confidentiality, Integrity Protection A CI/T implementation MUST support Transport Layer Security (TLS) transport for HTTP (HTTPS) as per [RFC9110]. TLS MUST be used by the server side (dCDN) and the client side (uCDN) of the CI/T interface, including the authentication of the remote end, unless alternate methods are used to ensure the security of the information in the CI/T interface requests and responses (such as setting up an IPsec tunnel between the two CDNs or using a physically secured internal network between two CDNs that are owned by the same corporate entity). The use of TLS for transport of the CI/T interface allows dCDN and uCDN to authenticate each other using the TLS client authentication and TLS server authentication. Once dCDN and uCDN have mutually authenticated each other, TLS allows: * dCDN and uCDN to authorize each other (to ensure that they are receiving trigger requests from, or responding to, an authorized CDN). * CDNI commands and responses to be transmitted with confidentiality. Sopher, et al. Expires 24 April 2025 [Page 95] Internet-Draft CDN Interconnect Triggers October 2024 * Protection of the integrity of CDNI commands and responses. When TLS is used, the general TLS usage guidance in [RFC9325] MUST be followed. The mechanisms for access control are dCDN-specific and are not standardized as part of this CI/T specification. HTTP requests that attempt to access or operate on CI/T data belonging to another CDN MUST be rejected using, for example, HTTP 403 ("Forbidden") or 404 ("Not Found"). This is intended to prevent unauthorized users from generating unnecessary load in dCDNs or uCDNs due to revalidation, reacquisition, or unnecessary acquisition. When deploying a network of interconnected CDNs, the possible inefficiencies related to the diamond configuration discussed in Section 2.8 should be considered. 8.2. Denial of Service This document does not define a specific mechanism to protect against Denial-of-Service (DoS) attacks on the CI/T interface. However, CI/T endpoints can be protected against DoS attacks through the use of TLS transport and/or via mechanisms outside the scope of the CI/T interface, such as firewalling or the use of Virtual Private Networks (VPNs). Depending on the implementation, triggered activity may consume significant processing and bandwidth in dCDN. A malicious or faulty uCDN could use this to generate unnecessary load in dCDN. dCDN should consider mechanisms to avoid overload -- for example, by rate- limiting acceptance or processing of triggers, or by performing batch processing. 8.3. Privacy The CI/T protocol does not carry any information about individual end users of a CDN; there are no privacy concerns for end users. The CI/T protocol does carry information that could be considered commercially sensitive by CDN operators and content owners. The use of mutually authenticated TLS to establish a secure session for the transport of CI/T data, as discussed in Section 8.1, provides confidentiality while the CI/T data is in transit and prevents parties other than the authorized dCDN from gaining access to that data. dCDN MUST ensure that it only exposes CI/T data related to uCDN to clients it has authenticated as belonging to that uCDN. Sopher, et al. Expires 24 April 2025 [Page 96] Internet-Draft CDN Interconnect Triggers October 2024 9. References 9.1. Normative References [RFC1930] Hawkinson, J. and T. Bates, "Guidelines for creation, selection, and registration of an Autonomous System (AS)", BCP 6, RFC 1930, DOI 10.17487/RFC1930, March 1996, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet: Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002, . [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, January 2005, . [RFC8006] Niven-Jenkins, B., Murray, R., Caulfield, M., and K. Ma, "Content Delivery Network Interconnection (CDNI) Metadata", RFC 8006, DOI 10.17487/RFC8006, December 2016, . [RFC8007] Murray, R. and B. Niven-Jenkins, "Content Delivery Network Interconnection (CDNI) Control Interface / Triggers", RFC 8007, DOI 10.17487/RFC8007, December 2016, . [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", STD 90, RFC 8259, DOI 10.17487/RFC8259, December 2017, . Sopher, et al. Expires 24 April 2025 [Page 97] Internet-Draft CDN Interconnect Triggers October 2024 [RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Ed., "HTTP Semantics", STD 97, RFC 9110, DOI 10.17487/RFC9110, June 2022, . [RFC9112] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Ed., "HTTP/1.1", STD 99, RFC 9112, DOI 10.17487/RFC9112, June 2022, . [RFC9325] Sheffer, Y., Saint-Andre, P., and T. Fossati, "Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)", BCP 195, RFC 9325, DOI 10.17487/RFC9325, November 2022, . [RFC9562] Davis, K., Peabody, B., and P. Leach, "Universally Unique IDentifiers (UUIDs)", RFC 9562, DOI 10.17487/RFC9562, May 2024, . 9.2. Informative References [ECMA404] ECMA International, "ECMA-404 - The JSON data interchange syntax", Edition 2, December 2017, . [ISO8601] ISO, "Data elements and interchange formats -- Information interchange -- Representation of dates and times", ISO 8601:2004, Edition 3, December 2004, . [MPEG-DASH] ISO, "Information technology -- Dynamic adaptive streaming over HTTP (DASH) -- Part 1: Media presentation description and segment format", ISO/IEC 23009-1:2014, Edition 2, May 2014, . [MSS] Microsoft, "[MS-SSTR]: Smooth Streaming Protocol", Protocol Revision 8.0, September 2017, . [POSIX.1] "The Open Group Base Specifications Issue 7", IEEE Std 1003.1 2018 Edition, 31 January 2018, . [REST] Fielding, R., "Architectural Styles and the Design of Network-based Software Architectures", Ph.D. Dissertation, University of California, Irvine , 2000. Sopher, et al. Expires 24 April 2025 [Page 98] Internet-Draft CDN Interconnect Triggers October 2024 [RFC6707] Niven-Jenkins, B., Le Faucheur, F., and N. Bitar, "Content Distribution Network Interconnection (CDNI) Problem Statement", RFC 6707, DOI 10.17487/RFC6707, September 2012, . [RFC7336] Peterson, L., Davie, B., and R. van Brandenburg, Ed., "Framework for Content Distribution Network Interconnection (CDNI)", RFC 7336, DOI 10.17487/RFC7336, August 2014, . [RFC7337] Leung, K., Ed. and Y. Lee, Ed., "Content Distribution Network Interconnection (CDNI) Requirements", RFC 7337, DOI 10.17487/RFC7337, August 2014, . [RFC7736] Ma, K., "Content Delivery Network Interconnection (CDNI) Media Type Registration", RFC 7736, DOI 10.17487/RFC7736, December 2015, . [RFC7975] Niven-Jenkins, B., Ed. and R. van Brandenburg, Ed., "Request Routing Redirection Interface for Content Delivery Network (CDN) Interconnection", RFC 7975, DOI 10.17487/RFC7975, October 2016, . [RFC8216] Pantos, R., Ed. and W. May, "HTTP Live Streaming", RFC 8216, DOI 10.17487/RFC8216, August 2017, . Acknowledgments The authors thank Kevin Ma for his input, and Carsten Bormann for his review and formalization of the JSON data. Authors' Addresses Nir B. Sopher Qwilt 6, Ha'harash Hod HaSharon 4524079 Israel Email: nir@apache.org Sopher, et al. Expires 24 April 2025 [Page 99] Internet-Draft CDN Interconnect Triggers October 2024 Ori Finkelman Qwilt 6, Ha'harash Hod HaSharon 4524079 Israel Email: ori.finkelman.ietf@gmail.com Sanjay Mishra Verizon 13100 Columbia Pike Silver Spring, MD 20904 United States of America Email: sanjay.mishra@verizon.com Jay K. Robertson Qwilt 275 Shoreline Dr Ste 510 Redwood City, CA 94065 United States of America Email: jayrobertson@acm.org Alan Arolovitch Viasat 1295 Beacon street Unit 249 Brookline, MA 02446 United States of America Email: alan.arolovitch@gmail.com Sopher, et al. Expires 24 April 2025 [Page 100]