code: function(instanceId, messageType, functionName, params) {
  			// loop through params and find functions and convert them to callbacks
  			var callbacks = [];
  			jQuery.each(params, function(i, e) {
  				if (typeof e === 'function') {
  					var cid = _registerCallback(e);
  					params[i] = cid;
  					callbacks.push(cid);
  				}
  			});
  			// check valid messageType
  			_apps[instanceId].socket.postMessage(
  				messageType + F2.stringify({
  					functionName:functionName,
  					params:params,
  					callbacks:callbacks
  				})
  			);
  		}
docs: Calls a remote function
  @method call
  @param {string} instanceId The app's Instance ID
  @param {string} messageType The message type
  @param {string} functionName The name of the remote function
  @param {Array} params An array of parameters to pass to the remote
  function. Any functions found within the params will be treated as a
  callback function.