Since you are dealing with a web service, you will not need to use Jakarta Cactus and may get away with writing simple old JUnit tests.
Tests will take two forms:
1. Does basic functionality work as expected?
-, , . / ? , - .
2. - ( SOAP/REST/XMLRPC)?
- - , , -. Axis/CXF/XFire -, JUnit .
, -. - Java, .Net, , .Net. SOAP , .