jSOAP is designed for mobile devices which runs a J2ME platform. With jSOAP you can deal with a webservice using SOAP. jSOAP is very usefull when you don't now before the application starts how is structured the webservice. No need of WSDL !
XUP (Extensible User Interface Protocol) is a SOAP-based protocol for delivering events and incremental UI updates. This project builds a web application development framework on top of XUP, consisting of a client, a server toolkit, and a template viewer.