Eclipse plugin launches Firefox using a profile within the workspace. It will be ${workspace_loc}/.plugins/com.ibm.etools.webtools.debug/Firefox/webtools/
In that profile will be two Firefox extensions, Firebug and Fireclipse. Fireclipse extends Firebug and it opens a XMLHTTPRequest to http://localhost:63636/UpdateNotifications. Eclipse runs a server at that port and listens. When the user tells Eclipse to do something to Firebug, the command is returned via the XMLHTTPRequest. Fireclipse executes the command and reissues the XMLHTTPRequest.
When Firebug operates on URLs, the URLs and line numbers are posted to the Eclipse server. When the server can find the file, the editor is positioned accordingly
