信息技术 开放系统互连 应用服务客体联系控制服务元素服务定义

[中文适用范围]： 此建议|国际标准定义了开放系统互连环境中 ASO 关联控制的 ACSE 服务。 ACSE 支持两种通信服务模式：连接模式和无连接模式。 ACSE 连接模式服务通过使用连接模式 ACSE 协议来提供（参见 ITU-T 建议书 X.227 bis | ISO/IEC 15954）。 ACSE 无连接模式服务（A-UNIT-DATA）通过使用无连接模式 ACSE 协议来提供（参见 ITU-T X.237 建议书 | ISO/IEC 15955）。 ACSE 中定义了五个功能单元。 强制内核功能单元用于建立和释放 ASO 关联。 可选的认证功能单元提供了用于交换信息的附加设施，以支持在关联建立期间的认证，而无需添加服务。 ACSE 认证设施可用于支持有限类别的认证方法。 可选的ASO上下文协商功能单元允许在关联建立期间提供多个ASO上下文。 可选的更高级别关联功能单元提供了识别 ASO 关联并透明地将数据传递给子 ASO 的功能，并允许在关联的生命周期内修改 ASO 上下文或 ASO 关联上的表示上下文。 此建议|国际标准不指定单独的实现或产品，也不限制计算机系统内实体和接口的实现。 不要求遵守本服务定义。 [外文原描述]： This Recommendation | International Standard defines ACSE services for ASO-association control in an open systems interconnection environment. ACSE supports two modes of communication service: connection-mode and connectionless-mode. The ACSE connection-mode service is provided by the use of the connection-mode ACSE protocol (see ITU-T Rec. X.227 bis | ISO/IEC 15954). The ACSE connectionless-mode service (A-UNIT-DATA) is provided by the use of the connectionless-mode ACSE protocol (see ITU-T Rec. X.237 bis | ISO/IEC 15955). Five functional units are defined in the ACSE. The mandatory Kernel functional unit is used to establish and release ASO-associations. The optional Authentication functional unit provides additional facilities for exchanging information in support of authentication during association establishment without adding services. The ACSE authentication facilities may be used to support a limited class of authentication methods. The optional ASO-context negotiation functional unit allows multiple ASO-contexts to be offered during association establishment. The optional higher level association functional unit provides for the facility to identify ASO-associations and transparently pass data to child ASOs and allows the ASO-context or the presentation context on an ASO-association to be modified during the lifetime of the association. This Recommendation | International Standard does not specify individual implementations or products, nor does it constrain the implementation of entities and interfaces within a computer system. No requirement is made for conformance to this Service definition.