title: How does a server-side command in vscode-languageserver-node know which is the current document?
body: <p>I'm developing an language extension for vscode for a DSL.  The architecture uses the vscode-languageserver-node infrastructure from microsoft's github, with a REST back-end that can evaluate the DSL. </p>
  
  <p>I have a command called Evaluate, which should send the current opened file text to the back-end server for evaluation.</p>
  
  <p>I tried modeling it as a server-side command that gets executed with <code>onExecuteCommand</code>, however in the server handler for this, there isn't really a way to find out which is the current focused source file in the client.  At least not that I can tell.</p>
  
  <p>I suppose I could just model it as a client command and then manually call <code>sendRequest(ExecuteCommandRequest)</code> with parameters that contain the info I need, to the server in that client handler, but I wonder if I'm missing something.</p>