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Tiny messenger

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Phan Hien

TinyMessenger is an event aggregator that allows for loosely coupled communication between classes. It provides a central hub for publishing and subscribing to messages. Classes can publish messages to the hub asynchronously, and subscribe to receive specific messages by message type or predicate. Subscriptions return a token that can be used to unsubscribe. Messages are simple classes that implement an interface. Proxies can also be used to deliver messages in a specific context like a UI thread.

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TinyMessenger Event aggregator/messenger for loosely coupled communication
Some scenarios Communication between Controllers/ViewModels. Service classes raising "events". Removing responsibilities from classes that receive external events (such as the AppDelegate in an iPhone application). Decoupling communication between classes.
How to use? var hub= new TinyMessengerHub(); Or var hub = container.Resolve<ITinyMessengerHub>();
How? Publishing //Publishing a message hub.Publish(new MyMessage()); //asyncronously if necessary hub.PublishAsync(new MyMessage()); // callback when publishing is completed hub.PublishAsync(new MyMessage(), MyCallback); // MyCallback is executed on completion
How ? Subscribing //Subscribe regardless of how many publishers there are hub.Subscribe<MyMessage>((m) => { MessageBox.Show("Message Received!"); }); // only receive the message if the content container "Testing" hub.Subscribe<MyMessageAgain>((m) => { MessageBox.Show("Message Received!"); }, (m) => m.Content == "Testing"); //Via proxy hub.Subscribe<MyMessage>((m) => { MessageBox.Show("Received via proxy"); }, DefaultTinyMessageProxy.Instance); // hub.Subscribe<MyMessageAgain>((m) => { MessageBox.Show("Message Received!"); }, (m) => m.Content == "Testing", true, DefaultTinyMessageProxy.Instance);
How ? Unsubscribing var token = hub.Subscribe<MyMessage>((m) => { MessageBox.Show("Message Received!"); }); //Unscubscribing messenger.Unsubscribe<TestMessage>(token ); //other way: token.Dispose()
Messages, How to define? //Simplest public class MyMessage : ITinyMessage { public object Sender { get; private set; } } //General public class MyMessageAgain : GenericTinyMessage<String> { public MyMessageAgain(object sender, String content) : base(sender, content) { // We now have a public string property called Content } } //If any subscribers call "Cancel" on our bool isCancelled = false; hub.Publish(new CancellableGenericTinyMessage<string>(this, "Testing", () => { isCancelled = true; }));
Proxy, How to define? // This example proxy (for WPF/Silverlight) uses the despatcher to // marshall messages back to the UI thread: public class DispatcherTinyMessageProxy : ITinyMessageProxy { private Dispatcher _Dispatcher; public DispatcherTinyMessageProxy(Dispatcher dispatcher) { _Dispatcher = dispatcher; } public void Deliver(ITinyMessage message, ITinyMessageSubscription subscription) { _Dispatcher.Invoke((Action)delegate { subscription.Deliver(message); }); } }
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Tiny messenger

  • 2. Some scenarios Communication between Controllers/ViewModels. Service classes raising "events". Removing responsibilities from classes that receive external events (such as the AppDelegate in an iPhone application). Decoupling communication between classes.
  • 3. How to use? var hub= new TinyMessengerHub(); Or var hub = container.Resolve<ITinyMessengerHub>();
  • 4. How? Publishing //Publishing a message hub.Publish(new MyMessage()); //asyncronously if necessary hub.PublishAsync(new MyMessage()); // callback when publishing is completed hub.PublishAsync(new MyMessage(), MyCallback); // MyCallback is executed on completion
  • 5. How ? Subscribing //Subscribe regardless of how many publishers there are hub.Subscribe<MyMessage>((m) => { MessageBox.Show("Message Received!"); }); // only receive the message if the content container "Testing" hub.Subscribe<MyMessageAgain>((m) => { MessageBox.Show("Message Received!"); }, (m) => m.Content == "Testing"); //Via proxy hub.Subscribe<MyMessage>((m) => { MessageBox.Show("Received via proxy"); }, DefaultTinyMessageProxy.Instance); // hub.Subscribe<MyMessageAgain>((m) => { MessageBox.Show("Message Received!"); }, (m) => m.Content == "Testing", true, DefaultTinyMessageProxy.Instance);
  • 6. How ? Unsubscribing var token = hub.Subscribe<MyMessage>((m) => { MessageBox.Show("Message Received!"); }); //Unscubscribing messenger.Unsubscribe<TestMessage>(token ); //other way: token.Dispose()
  • 7. Messages, How to define? //Simplest public class MyMessage : ITinyMessage { public object Sender { get; private set; } } //General public class MyMessageAgain : GenericTinyMessage<String> { public MyMessageAgain(object sender, String content) : base(sender, content) { // We now have a public string property called Content } } //If any subscribers call "Cancel" on our bool isCancelled = false; hub.Publish(new CancellableGenericTinyMessage<string>(this, "Testing", () => { isCancelled = true; }));
  • 8. Proxy, How to define? // This example proxy (for WPF/Silverlight) uses the despatcher to // marshall messages back to the UI thread: public class DispatcherTinyMessageProxy : ITinyMessageProxy { private Dispatcher _Dispatcher; public DispatcherTinyMessageProxy(Dispatcher dispatcher) { _Dispatcher = dispatcher; } public void Deliver(ITinyMessage message, ITinyMessageSubscription subscription) { _Dispatcher.Invoke((Action)delegate { subscription.Deliver(message); }); } }
  • 9. END