If you're using classic asp then you can use the serverXmlHtttp class.
Plenty of examples there.
As to receiving the request that depends on what Java Xml library you are using but basically you need to load the request's input stream into a DomDocument. Try some of the Java sites once you've picked a suitable processor.
There are examples of receiving xml in ASP under the link above, it's very similar using Servlets/JSP.
Joe (Microsoft MVP - XML