We wanted to implement a simple Java (JAX-WS) webservice on Google App Engine, but unfortunately this is not fully supported. All the javax.xml.* classes are available on Google App Engine, but not the com.sun.xml.ws.* classes that are normally used to implement a JAX-WS service. But with a little bit of custom code we can get a JAX-WS service to run on Google App Engine as can be seen in the SoapUI screenshot. You can download the public WSDL at https://redheap-jaxws.appspot.com/HelloWorldService.wsdl
|SoapUI test invoking HelloWorld service on Google App Engine|
You can use the normal JAX-WS annotations in your service class and use JAXB to marshal and unmarshal the request and responses. This is all very similar to a JAX-WS service on a JEE container. The thing you need extra is a custom HttpServlet that handles the HTTP POST, unmarshals the request payload to a java object using JAXB, invoke the actual web service class, marshal the web service class response back to XML and send it to the client.
This post describes all the steps to create a project using maven and complete it in JDeveloper 12c as well as deploying it to a local and remote server. If you prefer other build tools, like Apache ANT, or other Java IDE's you can still use similar steps but you might need to adjust them for your environment. The key part is the custom servlet which is the same for each setup.