The Web Services Reliable Messaging (WSRM) standard is an extension of the web service model to allow secure communication of information between web services clients and servers. By secure, I don’t mean in terms of security or encryption, but instead in terms of the reliability of sending and receiving the messages. sing a combination of sequencing, retransmission and two-way acknowledgement, WSRM is a much needed alternative in a grid environment for exchanging vital information.Here’s the intro extract from a new tutorial on understanding the basics of WSRM and its implementation at IBM developerWorks:

Discover how the Web Services Reliable Messaging (WSRM) standard defines an environment, sequence, and structure for sending and receiving reliable messages. The goal is for a WSRM-enabled system to transmit messages, even in the event of a network, platform, or simple application failure. In this tutorial, you’ll look at the WSRM specification, the basic mechanics of getting the system running, and an example of how the system works.You’ll be looking at the WSRM standard, why you need it, how you can use it, and how the WSRM standard provides reliable message exchange. In particular, you’ll look at the following topics:

• Reliable Messaging need
• Reliable Messaging Model
• Sequence example
• Reliable Messaging protocol
• Reporting faults
• Using WSRM for grid communication

You can read the full tutorial.