The XML Messaging Specification provides definitions of message headers needed for messages exchanged in an asynchronous or synchronous fashion. Synchronous message delivery is chosen when application communication requires message consumption and execution to be completed before a new message is allowed. Asynchronous messages are delivered independently without dependence on transport technology to correlate related messages. The rationale for choosing an asynchronous message delivery mechanism is based on the characteristics of the interaction between two software systems. Some of these reasons are:
· Support for long-running Request/Reply interactions may not be practical in synchronous session-oriented communication.
· Some messaging interactions require additional callback messages reporting on server activity which supplement the reply message.
· Clients may wish to interleave requests and replies to manage parallel or overlapping activities in multiple concurrent messaging conversations.
Headers defined for asynchronous messaging may also support synchronous interactions that rely on transport sessions for identification and correlation of related messages. However, there may be benefits of using the message header elements specified here even in synchronous interactions. The message header elements provide self-describing information about messages that may be useful for debugging or tracking message traffic. Their use may also enable future migration to different message transports.
The XML Messaging Specification uses established, openly referenceable industry standards for XML messaging where possible. It only specifies extensions to existing industry standards when needed to meet the immediate requirements for messaging in a SEMI Standard application context. The intent of this Standard is not to replicate existing standards or offer competing specifications, but to align with and cite the usage of existing standards.
Referenced SEMI Standards
SEMI E120 — Specification for the Common Equipment Model (CEM)
SEMI E125 — Specification for Equipment Self Description (EqSD)
SEMI E132 — Specification for Equipment Client Authentication and Authorization
SEMI E134 — Specification for Data Collection Management
· Support for long-running Request/Reply interactions may not be practical in synchronous session-oriented communication.
· Some messaging interactions require additional callback messages reporting on server activity which supplement the reply message.
· Clients may wish to interleave requests and replies to manage parallel or overlapping activities in multiple concurrent messaging conversations.
Headers defined for asynchronous messaging may also support synchronous interactions that rely on transport sessions for identification and correlation of related messages. However, there may be benefits of using the message header elements specified here even in synchronous interactions. The message header elements provide self-describing information about messages that may be useful for debugging or tracking message traffic. Their use may also enable future migration to different message transports.
The XML Messaging Specification uses established, openly referenceable industry standards for XML messaging where possible. It only specifies extensions to existing industry standards when needed to meet the immediate requirements for messaging in a SEMI Standard application context. The intent of this Standard is not to replicate existing standards or offer competing specifications, but to align with and cite the usage of existing standards.
Referenced SEMI Standards
SEMI E120 — Specification for the Common Equipment Model (CEM)
SEMI E125 — Specification for Equipment Self Description (EqSD)
SEMI E132 — Specification for Equipment Client Authentication and Authorization
SEMI E134 — Specification for Data Collection Management
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