WS-Reliable Messaging

WS -Reliable Messaging ( Reliable Messaging ) is a specification from the area of ​​WS-*, which guarantees that messages sent arrive even in the event of failure of individual software components at the receiver.

For this purpose, each a promoters are virtually at the transmitter and receiver side interposed on middleware level.

Sub-specifications

WSRM includes the sub specification WS- Reliable Messaging Policy Assertion, specifies the possible directives on Reliable Messaging. These assertions can then be integrated via WS-Policy.

Outline of Communication

Through this process it is ensured that a) has really gotten the message, the recipient, and b) the sender also knows about it.

Operation and Example

This can also work on a longer chain of messages by the broker at the transmitter in the SOAP header additionally inserts an identifier and a message number. If a message is the last of a series of messages, as an additional element is still inserted, showing the agent on the receiver side that no other message more will come. In the respective acknowledgments of receipt of the mediator are at the receiving end then in addition to, to which he refers identifier and the numbers of messages that it has already received, or are still missing. For example, the following excerpt answer would indicate that the messages were received 1,2, and 4 to 7 and 3 still missing:

< - Etc. -> 3 < - Etc. -> There are four possible delivery guarantees ( "delivery assurances " ):

  • AtLeastOnce: Every message is delivered at least once, while it is also possible that she gets much more often. If a delivery is not possible, an error must be reported.
  • AtMostOnce: Every message is delivered at most once. It is possible that a message does not arrive, but the recipient will never receive a message more than once.
  • ExactlyOnce: Every message is delivered exactly once. Duplicates are excluded and messages can not be lost. If a delivery is not possible, an error message is triggered.
  • Inorder: All messages are exactly arrive in the order in which they were sent. This warranty can be combined with each of the three preceding delivery guarantees.
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