Standards for web services.

• Role of the Best Practices Working group

Web Services interoperability is important since it will be an interface that many applications will elect to use to caBIG tools. I believe the best practices working group so educate and perhaps may go as far as to set requirements such as in the caBIG compatibility document. What do others think about possible roles of the group?

• Web Services Interoperability Resources

The best resource is the WS-I.org (Web Services Interoperability Organization). The WS-I.org publishes a set of documents which detail what it means to be WS-I compliant. They provide software to test particular services for compliance and multiple vendors have provided example complaint services to guide developers in achieving compliance on their own services.

• Book Suggestion: Perspectives on Web Services This book might be too in depth but has good design principles for web services and service oriented architectures in general. Specifically, one important lesson is that a public interface should be developed in UML and then translated carefully to WSDL. In practice, most succesful developers of web services tend to follow the following path:

1. Model public interface in UML.
2. Translate UML into WSDL (possibly with aid of automatic tools).
3. Work to ensure that WSDL is WS-I compliant.
4. Perform compatibility testing with subset of Web Services client toolkits.

At steps 3 and 4, is where most of the interoperability problems are solved and a useful feedback model becomes important. Most of the time, the interoperability problems at those steps are caused by models which incorporate specific programming language artifacts and assumptions, so the iteration of this process can result in a cleaner, more graceful interface in the end.

• The following articles I wrote are sometimes useful in explaining why web services are interoperable simply by definition. Part 3 is a good summary and links to part 1 and part 2.