PUBLIC MARKS with tags interface & xmlhttprequest

FileTreePanel is client-server application where client (browser) provides the user interface (UI) which displays the tree and context menu, handles drag & drop operations, etc. The filesystem that is displayed and managed by the UI is stored on a server. Therefore, we need some communication layer between client and server. Client sends a command to server, server processes this command and responds with a result. Client in turn processes the response and display results. All this communication is running in the background by Ajax (XMLHttpRequest) calls. The XMLHttpRequest is not used directly but the Ext JS - JavaScript Library ajax layer is used for this purpose. Client requests data from server with standard POST method and server is expected to respond with JSON (JavaScript Object Notation) string and appropriate HTTP headers.