Implement asynchronous message exchange

Level: intermediate

Example

Implement asynchronous exchange among the modules.

1. Set the configuration object as a parameter of the handler function in the module that publishes the message.

2. Add a callback function to the configuration object.

   Example that publishes messages and retrieves the result

   ...
   this.sandbox.publish("AsyncMessageResult",
   /* Configuration object specified as a handler function parameter. */
   {
       /* Callback function. */
       callback: function(result) {
           this.Terrasoft.showInformation(result);
       },
       /* Scope of the callback function execution. */
       scope: this
   });
   ...

3. Return asynchronous result in the handler method of the subscriber module the module subscribes to a message. Use the callback function parameter of the published message.

   Example that subscribes to a message

   ...
   this.sandbox.subscribe("AsyncMessageResult",
   /* Message handler function. */
   function(config) {
       /* Handle the incoming parameter. */
       var config = config || {};
       var callback = config.callback;
       var scope = config.scope || this;
       /* Prepare the resulting message. */
       var result = "Message from callback function";
       /* Execute the callback function. */
       if (callback) {
           callback.call(scope, result);
       }
   },
   /* Execution scope of the message handler function. */
    this);
   ...