James is an Enterprise Architect for The Hartford Financial Services Group and wrote a really good book that you should read.

James observes that there is far more to a contract than simple WSDL.  Contracts also define:

  • Message interchange formats defined using XML Schema
  • Message Exchange Patterns (MEPs) defined using WSDL
  • Capabilities and requirements defined using WS-Policy
  • BPEL may be used as a business-process level contract for aggregating multiple services

James has a great blog - I hope he starts blogging again soon.