spring+jaxws: is there a better way than static variables to keep global status?

Question

I have a webservice (cxf) which creates a new Thread each time a time-consuming method is invoked, returning an ID to the client, passed as a token to another web method to check that specific thread's execution state:

public String doWork(){
    String id = /***randomnly generates an ID****/
    executor.execute(**some runnable**);

   // need to save the guy above
   return id;
}

public String checkStatus(String id){
    /* Here I would basically access to an hashmap
       of tasks, pick the one identified by that ID
       and check its state */
}

My problem, as you can see above, is to keep a reference to the task(s) so that I can track its execution. Idea I came up with is the following:

@Webservice
public class MyService{
    private static HashMap<String, Future> futures = new HashMap<String,Future>();

But is there some better way?Moreover what could be the possible drawbacks of this choice?

Answer 1

Another alternative for storing global state is using a database. Not knowing all the details of your application, the only thing that comes to mind is that depending on how they're used static variables can have issues with thread safety.

Answer 2

It helps to know a few things about the underlying programming model of Java EE servlets, upon which JAX-WS and such are built. This answer explains things well.

To retain information associated with a client for the duration of a session, you can obtain the session in the body of your method and store information in it:

Message message = PhaseInterceptorChain.getCurrentMessage();
HttpServletRequest request = (HttpServletRequest)message.get(AbstractHTTPDestination.HTTP_REQUEST);
HttpSession  session = request.getSession(true);
session.setAttribute("id", id);

Upon subsequent method invocations you can retrieve session data in the same manner.

A really basic (ancient) tutorial: Maintaining Client State.