There have been a number of events over the past week that have gotten me thinking about XML Web Services and how the technologies have been handicapped by the complexities of the W3C's XML Schema Definition Language (XSD) and Microsoft & IBM's Web Service Definition Language (WSDL). The events that brought this issue to mind have been

• Contributing to Mike Champion's efforts in putting together Microsoft's submission to the W3C Workshop on XML Schema 1.0 User Experiences and having to revisit the various interoperability problems caused by the complexity of XSD.

• A recent paper by Steve Loughran and Edmund Smith entitled Rethinking the Java SOAP Stack which argues that since the complexity of Object<->XML mapping based on XSD/WSDL is too difficult that Java SOAP toolkits should simply work with XML directly instead of doing data binding of XML to objects.

• A recent post by Steve Maine, who works on the XML Web Services team at Microsoft, entitled Travelling through hyperspace where in response to the various arguments about the complexities of XSD and WSDL he states "WSDL, XSD, and SOAP are facts of life in the web services world"

• The W3C's creation of the public-web-http-desc@w3.org mailing list to discuss the creation of a web services description format (i.e. a WSDL replacement) for RESTful web services

These are definitely interesting times for XML Web Services. The complexity of the technologies that form the foundations of SOA is now pretty much acknowledged across the industry. At the same time more and more people are taking the idea of building web services using REST very seriously. I suspect that there might be an opportunity here for Microsoft to miss the boat if we aren't careful.