Web Services Platform Architecture [Electronic resources] : SOAP, WSDL, WS-Policy, WS-Addressing, WS-BPEL, WS-Reliable Messaging, and More نسخه متنی

10.3. Architectural Concepts

Of all the Chapter 5, "WS-Addressing."

Reliable messaging is enabled by virtue of something called a Sequence, which is effectively a shared context for a set of messages to be delivered with a common quality of service between a sending and a receiving endpoint. Each message within a Sequence is assigned a unique message number, starting with 1 and increasing monotonically, by one, for each subsequent message in the Sequence. The receiving endpoint acknowledges receipt of the messages within a Sequence by indicating the range of messages it has received using a SequenceAcknowledgement. Each SequenceAcknowledgement message carries the acknowledgement information for all the messages that have been received within a Sequence. Hence, a SequenceAcknowledgement message does not require retransmission should it fail to reach the sending endpoint of the original message, because the information is sent with a subsequent SequenceAcknowledgement message.

As with the other reliable messaging specifications proposed, WS-Reliable Messaging is defined as a set of SOAP Header extension elements that enable a range of qualities of service for a Web service, from at-most-once through exactly-once delivery assurances, preservation of message order, and duplicate detection. However, unlike the other proposals, WS-Reliable Messaging accomplishes this with a much simpler syntax and more efficient processing semantics.