|Internet-Draft||sdfType for Links||June 2023|
|Bormann||Expires 5 December 2023||[Page]|
This document defines and registers an sdfType "link" for the Semantic Definition Format (SDF) for Data and Interactions of Things (draft-ietf-asdf-sdf).¶
This note is to be removed before publishing as an RFC.¶
Status information for this document may be found at https://datatracker.ietf.org/doc/draft-bormann-asdf-sdftype-link/.¶
Discussion of this document takes place on the A Semantic Definition Format for Data and Interactions of Things Working Group mailing list (mailto:email@example.com), which is archived at https://mailarchive.ietf.org/arch/browse/asdf/. Subscribe at https://www.ietf.org/mailman/listinfo/asdf/.¶
Source for this draft and an issue tracker can be found at https://github.com/cabo/sdftype-link.¶
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The Semantic Definition Format for Data and Interactions of Things (SDF, [I-D.ietf-asdf-sdf]) is a format for domain experts to use in the creation and maintenance of data and interaction models in the Internet of Things.¶
A common data type that occurs in the modeling of IoT devices is the link. [RFC8288] defines the concept of Web Linking, which complements the target URI that any link will contain, with additional parameters, such as the "link relation type" that explains the relationship expressed by the link, as well as "target attributes" that provide additional information about the target of the link (without a need to "dereference", i.e., follow, the link).¶
This document defines and registers an sdfType "link" for the Semantic Definition Format. This type models an abstract "serialization" [RFC8288] of a link, in a way that is compatible with the way SDF maps information models to its data modeling language.¶
Links play an important role in SDF modeling both during definition
time (for adding information to a model, as e.g., in
during run time (for making links to instances into a subject of data
and interaction modeling).
The present document is an early attempt at addressing the run-time
usage of links, in particular links that fit the Web Linking [RFC8288]
A related draft [I-D.laari-asdf-relations] addresses definition-time links, but does
seem to touch modeling run-time use of links as well (e.g., by
discussing "writable" link relations).¶
Not all links used in ecosystems are based on URIs.
E.g., OMA has "object links", which are pairs of numbers (object/instance).
These ecosystem links may have some structure that should be modeled
in the SDF model (e.g., where the object id part of a link always has
to have a specific value).
This structure can be mapped into URI strings using some convention,
e.g., an OMA object link could be
oma-object is placeholder for a URI scheme to be defined).
However, burying structural components of the ecosystem-specific link
in a string syntax makes it hard to access and control those
components from the model.¶
TODO: Examples are needed to show how the OCF collection pattern is addressed by the current specification.¶
The security considerations of [RFC8288] apply in a general way, although modeling a link as a datatype does not incur all of the security considerations that will apply to actually interchanging these links.¶
// RFC Ed.: please replace RFC XXXX with this RFC number and remove this note.¶
IANA is requested to register the sdfType "link" in the "sdfType Values" sub-registry in the "SDF Parameters" registry, with the following completion for the registration template:¶