SOAP-based Web services implementations are over the HTTP protocol. However, in implementations that require SOAP to be enabled over a protocol more reliable than HTTP, message-oriented middleware (MOM) is an obvious choice. In addition, the features of commercially available MOM, such as guaranteed message delivery, transactional support, encryption, high performance, and high availability, make the case for combining SOAP and MOM more compelling and appealing.
Service providers can scale horizontally by adding more servers for listening to the same MOM queues. The service consumer will remain completely agnostic of such changes at the server.
Applications requiring guaranteed delivery can rely on the persistent capabilities of MOM, which ensure message delivery in the event of hardware and software crashes.
SOAP-based Web services implementations are over the HTTP protocol. However, in implementations that require SOAP to be enabled over a protocol more reliable than HTTP, message-oriented middleware (MOM) is an obvious choice. In addition, the features of commercially available MOM, such as guaranteed message delivery, transactional support, encryption, high performance, and high availability, make the case for combining SOAP and MOM more compelling and appealing.
Service providers can scale horizontally by adding more servers for listening to the same MOM queues. The service consumer will remain completely agnostic of such changes at the server.
Applications requiring guaranteed delivery can rely on the persistent capabilities of MOM, which ensure message delivery in the event of hardware and software crashes.
http://www.javaworld.com/javaworld/jw-02-2006/jw-0220-axis.html?page=1
SOAP vs REST
http://radovanjanecek.net/blog/archives/186.html