I've read many articles on the web about the future of web services. Some say Java will win the battle and some say that .NET will win the battle. A few state that it is not a matter of winning the battle but what role each platform will fill in web services. I tend to agree with the assessment that Java and .NET will each fill seperate roles in web services. I noticed your book includes a chapter on using web services to communicate between Java and .NET. Do you have an opinion on what roles each platform will fall into as web services become more prominent?
Both J2EE (Java) and .NET would follow the role as Web services providers (typically Application infrastructure). The emergence of WS-I Basic Profile, makes both worlds to agree upon an interoperability standard. This makes a J2EE Application invoking a .NET component using SOAP and vice versa. In both cases, the message exchanged including security credentials will interoperate as well. Does it answer your question ?
As long as there is an agreed upon standard then .NET and J2EE can co-exist nicely. In fact, you should be able to invoke a web service without caring what is at the other end. I have worked with web services in .NET and they are very simple to set up. Of course, it is easy to be a .NET web service client if you are using visual studio but since .NET uses the standard discovery methods there is really no reason that it can't be easy for a Java programmer as well.