IBM's AlphaWorks continues to do interesting work around Web Services, Java, and XML. One of their innovations is Business Process Execution Language for Web Services (BPEL4WS), a process-description language that's used to describe how Web Services interact with each other (and with other entities) to form useful processes. Though details of BPEL4WS remain sketchy and one hopes they'll come up with a catchier name for it, the idea of a language that combines the best features of Microsoft's XLANG and IBM's Web Services Flow Language (WSFL) is indeed appealing. 

BPEL4WS allows you to specify a composite Web Service. Such a Web Service appears externally like any other Web Service, and may be advertised as such with Web Service Description Language (WSDL) and a directory scheme. BPEL4WS is used to tie disparate Web Services together, specifying their inputs and outputs either as internal to the composite service (i.e., the output of one feeds the input of another, and the two ports aren't exposed externally) or external (in which the input or output of a member Web Service serves as an input or output of the composite service as a whole). You use, for example, an <invoke> command to refer to another Web Service, and a <receive> tag to take input from an entity external to the composite service. Overall, the language looks like a handy way to modularize your Web Services and re-use them in bigger projects.

IBM has also released a Java implementation of BPEL4WS called BPWS4J (it's hard to believe they passed up the opportunity to call it "BPEL4WS4J"). This Java library can interpret BPEL4WS documents and allows Java programs to refer to them via SOAP. They've also released a plug-in for the Eclipse development environment that makes the creation of spec-compliant BPWS4J documents a bit easier.

While on AlphaWorks, check out Robocode! It's a Java teaching tool in which you write classes that represent fighting robots. You write a robot and pit it against others -- very cool! Whatever happened to Karel?