A simple, light-weight application level event aggregator which facilitates the exchange of messages between objects without direct references.
A soundComponent needs to be notified whenever a user clicks on any button.
MessageBus.Default.FromAny().Where<ButtonClickMessage>().Notify(soundComponent)
A taxCalculator needs to be notified whenever shopping cart is changed.
MessageBus.Default.From(shoppingCart).Notify(taxCalculator);
LightMessageBus uses a simple publisher/subscriber pattern.
- Subscribers use the MessageBus to subscribe to messages they wish to be notified about. They may wish to filter messages by the source, type of message or some other predicate.
- Publishers use the MessageBus to publish messages to the potential subscribers
- Neither subscribers nor publishers have any references to each other. They simply use a common communication channel - the MessageBus
The pub/sub pattern enables you to promote decoupled architecture in your application. Since there is no need for various objects (views, models, controllers, ...) to know of each other existence - you are free to develop them independently in isolation. Such architecture enables testing, refactoring and limits the propagation of changes through the system.
Using delegates and/or events requires a reference between the publisher and the subscriber (subscribers reference publishers or vice-versa). Any change to the referenced class will affect the other. Such change may even propagate through the system resulting in significant changes due to a small cause.
LightMessageBus uses LINQ-like, fluent syntax for maximum readability and flexibility. The basic building blocks of a LightMessageBus registration expression are: From, Where and Notify.
First we define the publishers:
From- specifies publisher(s) of interest to subscriber.FromAny- specifies any publisher.
Next we optionally define the messages:
Where- specifies the types of messages of interest to subscriber.
Lastly we define the subscriber:
Notify- specifies the subscriber.