Hello there,
Http is a protrocol that limits the communication between only two ends(one cliente and one server), thus you can forward the request only to resources located in that server. If you need to communicate with another server , you need another conection and another request. What you are trying to accomplish, is create a pipeline of comunication between your servers (see Pipes and Filters -POSA). You will need to use one application as a httpProxy (You can implement this using a Front Controller and App.Controller or an an Intercepting Filter-JEE Core
Patterns) in front of target server, handle the request, extract the http message payload, create another request, copy old payload to the new request, forward the new request to the target server(you can use java.net). Also you can use SAAJ with that strategy to handle soap messages. I'm not very familiar with Apache HttpClient API, but i'm pretty sure it's an abstraction layer for what i described here.