When it comes to Web Services, SOAP (Simple Object Access Protocol) is the complete package for Enterprise-level Transaction and Messaging Security. That is where SOAP reigns supreme.

1. Web Services Security (WSS)
WSS supports identity through intermediaries - not just point-to-point (SSL) - via XML Signature (data integrity) and XML Encryption (data privacy).

2. Web Services Atomic Transaction (WS-AT)
SOAP provides ACID compliant, two-phase commits across distributed transactional resources via WS-AT (an OASIS protocol). 

Web Services Reliable Messaging (WS-RM)
WS-RM is a messaging protocol that has successful/retry logic built-in and provides end-to-end reliability in the presence of software component, system, or network failures.

Client Project:

 For the trade show registration application developed for Microsoft and Symbol Technologies, we  used SOAP to support transmission of data from Symbol's hand-held devices running Pocket PC and CE, over the web to a Microsoft SQL server for tracking.