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Box 1331 Piscataway, NJ 08855-1331, USA +1 (908) 562-3800 +1 (908) 562-1571 [FAX] P1003.0/D14 Section 3: POSIX Open System Environment _R_e_s_p_o_n_s_i_b_i_l_i_t_y: _F_r_i_t_z _S_c_h_u_l_z The POSIX Open System Environment (OSE) is a collection of concepts that provide a context for user requirements and standards specification. It provides a minimum, standard set of conceptual information system building blocks with associated interfaces and functionality. The POSIX OSE consists of a reference model, service definitions, standards, and profiles. These OSE concepts are also intended to be conventional within computer science. The intention is not to break new ground, but to establish a minimum and unambiguous terminology and set of concepts for identification and resolution of portability and interoperability issues. The POSIX Open System Environment is defined in five parts: (1) General requirements are identified that apply to the POSIX OSE as a whole in 3.1. (2) A reference model is developed that unambiguously identifies the system under consideration for purposes of specification. The POSIX OSE reference model described in 3.2 defines system elements to identify interfaces across which service requirements should be satisfied. The elements are chosen to expose those interfaces that are significant to the profile writer or user. (3) Using the interfaces identified in the reference models, each subclause of Section 4 categorizes and describes the basic services available to users across each interface. The services are defined in a generic way, based on the reference model, user requirements, and current industry practice, rather than any given implementation. Definition of the service requirements is not constrained by the availability of standards. Service requirements that are not currently satisfied via standards are discussed in either the Emerging Standards subclause, or under Gaps. Copyright (c) 1991 IEEE. All rights reserved. This is an unapproved IEEE Standards Draft, subject to change. 3 POSIX Open System Environment 15 P1003.0/D14 GUIDE TO THE POSIX OPEN SYSTEMS Each clause of Section 4 begins with a more detailed and specialized version of the reference model to provide a context for service specification. After defining the interfaces and services, each of the Section 4 clauses concludes with a discussion of standards that are related to the services. (4) Section 5 discusses issues and requirements that directly affect all of the service categories, such as internationalization, security, and administration. (5) Section 6 provides guidelines for creating profiles that address various application domains. This is a brief description of how the reference model and services are applied to a variety of existing types of systems. Section 7 describes current POSIX profiles and profiling activities. e Definition of the service requirements is not constrained by the availability of standards. Services requirements that are not currently satisfied via standards are discussed in either the Emerging Standards subclause, or under Gaps. 3.1 POSIX Open System Environment - General Requirements The POSIX Open System Environment should satisfy the requirements in the following list: (1) Application Portability at the Source Code Level The POSIX OSE shall enable application software portability at the source code level. Rationale: Comprehensive and consistent source code level service specifications allow porting of applications among processors (ideally without modification). Binary portability requires too tight a coupling with the processor implementation. (2) System Interoperability The POSIX OSE shall enable application software and system service interoperability. Rationale: Communications services and format specifications allow two entities participating in a distributed system to exchange and make mutual use of data, including: Copyright (c) 1991 IEEE. All rights reserved. This is an unapproved IEEE Standards Draft, subject to change. 16 3 POSIX Open System Environment