Java Reference
In-Depth Information
Policies are implemented in XML files that are then associated with the WSDL. You either
have to manually associate them with the WSDL by writing them inline, or you can sometimes
use a vendor's proprietary convenience mechanism to get them attached to the service without
having to muck about in the WSDL.
Source and destination
WS-ReliableMessaging defines a way to keep track of and manage the reliable message de-
livery between two parties, the source and the destination. A source is an application endpoint
that sends a message (a client), and the destination is the endpoint to which messages are de-
livered. Messages in WS-RM are not sent directly to the endpoint, but are submitted to the
WS-RM implementation for handling, which starts the reliability guarantee.
NOTE
The manner in which WS-RM implementations handle the persistence of messages at the source in
order to retry unacknowledged messages is out of scope for the specification. It's handled differently
by different vendors; WebLogic, for example, builds on its JMS Store-And-Forward framework.
The WS-ReliableMessaging protocol
WS-RM follows this basic order of events in the lifetime of a reliable message exchange:
1. Preconditions are established between the source and destination to ensure policies are un-
derstood.
2. When a message is submitted to the runtime, the WS-RM source requests that the destin-
ation create a new sequence.
3. The WS-RM destination creates a sequence, assigns it a unique ID, and establishes
memory allocation for temporary persistence of the sequence.
4. The WS-RM source sends its first message in the sequence, assigning it an ordinal posi-
tion (message number).
5. The WS-RM source sends additional messages as it likes, incrementing each message
number by 1. Each additional message contains the sequence ID so that the destination
can correlate the message properly.
6. The last message in the sequence indicates in a header that it is the last message.
7. The WS-RM destination acknowledges receipt of all of the messages that it has.
8. If any messages were lost in transit, this is indicated in the acknowledgment.
