title: How to add custom data source to GeoServer WMS service?
body: <p>I'm installing GeoServer as a WMS server to cooperate with OpenLayers.</p>
  
  <p>The trouble is that I have to use 3rd-party tile source which is provided through web service.
  So I guess I have to tweak GeoServer to fetch tile image from 3rd-party server and response to OpenLayers request.</p>
  
  <p>Is this idea correct? What should I do to accomplish that?</p>
  
  <p>Any suggestion would be appreciated.</p>
  
  <p>Thanks a lot.</p>