1

Scope

This part of ISO/IEC ISP 11188 introduces the concept of the minimal set of OSI upper layer facilities? for basic c ommunications applications. (?The upper layer facilities considered in this part of ISO/IEC ISP 11188 are ACSE, Presentation, and Session.) A basic communications application simply requires the ability to open and close connection- oriented communications with a peer and to send and receive messages with the peer. It is expected that a large portion of potential OSI applications will be basic communications applications.

1.1

General This part of ISO/IEC ISP 11188 specifies the minimal set of upper layer facilities required for the support of basic communications applications. The minimal OSI facilities are referred to as mOSI.

This part of ISO/IEC ISP 11188 defines the mOSI facilities in terms of identified features of the upper layer PICS proformas - the ACSE (ISO/IEC 8650-2), the Presentation layer (ISO/IEC 8823- 2), and the Session layer (ISO/IEC 8327-2). The identified features of these PICS proformas are specified in annexes A, B, and C, respectively.

This part of ISO/IEC ISP 11188 complies with the requirements stated in ISO/IEC ISP 11188-1, Basic connection oriented requirements.

This part of ISO/IEC ISP 11188 may be referenced by two classes of entities: upper layer users and upper layer providers.

- mOSI users represent basic communications applications. mOSI u sers may be profiles (such as A-profiles identified in ISO/IEC TR 10000-2) or specifications of basic communications applications that are not represented by a formal profile. An API specification is a special case of the latter. The term referencing specification is used in this part of ISO/IEC ISP 11188 to represent this set of mOSI users.

- mOSI providers represent implementations of the upper layer facilities that provide (at a minimum) the facilities defined in this part of ISO/IEC ISP 11188. The term referencing implementation i s used in this part of ISO/IEC ISP 11188 to represent this set of mOSI providers.

A referencing specification (a mOSI user) may claim compliance? to t his part of ISO/IEC ISP 11188. (?Compliance deals with one specification referencing another specification.) It may do so if the OSI upper layer facilities that it requires can be expressed by the facilities of this part of ISO/IEC ISP 11188. Subclause 2.1 summarizes the requirements for making such a statement. Annex D provides a proforma for a profile requirements list (PRL) for a compliant application.

A referencing implementation (a mOSI provider) may claim conformance? to this part of ISO/IEC ISP 11188 (?Conformance deals with a physical implementation that references a particular specification.) It may do so if the OSI upper layer facilities that it provides include those expressed in this part of ISO/IEC ISP 11188. That is, an implementation may contain more upper layer facilities than those required to be conformant to this part of ISO/IEC ISP 11188. However, they must contain at least those of this part of ISO/IEC ISP 11188.

Annex F assigns object identifier values for specific generic definitions of application context, abstract syntax, and transfer synt ax.

1.2

Position within the Taxonomy This part of ISO/IEC ISP 11188 does not specify a full A- profile, and therefore is not included in the taxonomy of ISO/IEC TR 10000-2.