Send waiting response to server while requesting other server with middleware

I am using Spring Jersey framework. I want to implement waiting response to be returned to server while middleware is processing.

Sceniro:

• 
  

  Server A request to middle ware. Middleware server start processing on the request and request to another Server B.

  
  


• 
  

  While requesting Server B from middleware if the response takes longer time than 30 seconds middleware should send Response-A as "request in progress"

  
  


• After receiving response from server B it should again send response B to Server A.


• if Server B responds in 30 seconds than Response - A will be neglected.

Code Snippets:

EndPoint (Controller)

@Path("/")
  @GET
  public Object getResponse(@Context HttpServletRequest request,SomeDataWrapper someData)
  {
    // Server - A call this method
    return service.getResponse(someData);
  }

Service Method : (That will call Server B)

public Object getResponse(SomeDataWrapper someData){

    // Code to call another Server B
    Object response = callServerB();

   // How to achieve threading mechanism here to response back to server a for waiting 
        return response;
  }

Related Model classes (Wrappers)

 public class SomeDataWrapper{

    private long id;
    private String data;

    //getter setters goes here
  }

 public class WaitResponseWrapper{

    private long id;
    private String waitingStatus;
    private String someText;

    //getter setters goes here
  }

How to achieve Threading mechanism in service so that the response can not be swallowed? much appreciated with code snippet for threading mechanism. Thank you