• The need for more than just the basics
• Other specifications that provide more

• Of course, writing a program in terms of a Web Service means that:
  • the program is dependent on a connection to the Internet,
  • the availability of the computer and the webserver of the Web Service,
  • whether the Web Service still maintains the same contract as when the program was written,
  • ...
• Although the facilities described so far enable us to provide and access Web Services, it only establishes the basics: ...
• ...a lot more has to be done if Web Services are to be used to provide a reliable software service.

Various companies have been working on producing specifications for a number of areas that build on the basics of Web Services. These include:

• Security: WS-Security, WS-Trust, WS-SecureConversation, WS-Federation
• Reliable Messaging: WS-ReliableMessaging
• Transactions: WS-Coordination, WS-AtomicTransaction, WS-BusinessActivity

These specifications are examined by the papers at [9, 11]. Other papers that look at the bigger picture include those at [10, 16, 29].

In the next section of this document, we just consider the first of these: WS-Security.