Reliable Messaging can be critical to asynchronous Web Services communication and is REQUIRED as part of the STAR Level 2 Rules. The STAR Web Services specification is based upon the OASIS WS-ReliableMessaging specification v1.1 . This specification provides the foundations for providing enhanced Web Service communication with the following capabilities to assist in guaranteeing delivery: Delivery assurances, Delivery Notification, Conversational integrity, and Failure notification. WS-ReliableMessaging supports all of the STAR Delivery Assurance profiles.

WS-ReliableMessaging has close ties to the WS-Policy framework and recommends the use of WS-Security specifications. WS-Policy can be used with reliable messaging but is currently not a requirement.

WS-Reliable Messaging Version 1.1 was formally adopted by OASIS in June of 2007. Currently, the WS-I Reliable and Secure Profile, is in draft status, and part of the work is based on the new WS-ReliableMessaging 1.2 specification. Some of the Rules for interoperability are based off of profiles from WS-I Reliable and Secure profile. As this profile is updated, STAR will update these requirements. Due to differences in the versions of Reliable Messaging supported by the profile, STAR has modified the rules slighty.

For more information on what Reliable Messaging is, and what is is used for, the InfoQ article by Paul Freemantle, "An Introduction to Web Services Reliable Messaging" [Freemantle2006] is a good starting point. Freemantle covers the basics of WS-ReliableMessaging 1.1, and also reviews the changes that have occured since WS-ReliableMessaging 1.0 was introduced. Several examples in this chapter are based on his article.