Configuration Conventions

In addition to supporting an explicit configuration model, RabbitBus also provides a convention-based configuration model which allows you to define conventions for the registration of messages as well as the auto-subscription of message handlers.

Custom conventions are configured through the use of an overloaded BusBuilder.Configure() method which accepts an IAutoConfigurationModel. For convenience, an AutoConfigurationModelBuilder type is supplied which provides a fluent interface for the configuration of IAutoConfigurationModel instances.

Publish Configuration Conventions

To configure RabbitBus to automatically register message types for publication, the AutoConfigurationModelBuilder type is used to denote the assemblies to scan along with the IPublishConfigurationConvention instances to use. The following example scans the current executing assembly for messages which are matched by a MyPublishConfigurationConvention type:

_bus = new BusBuilder()
	.Configure(new AutoConfigurationModelBuilder()
		.WithAssembly(Assembly.GetExecutingAssembly())
		.WithPublishConfigurationConvention(new MyPublishConfigurationConvention())
		.Build())
.Build();

The MyPublishConfigurationConvention type in the above example might be implemented as follows:

	public class MyPublishConfigurationConvention : PublishConfigurationConventionBase
	{
		public override bool ShouldRegister(Type type)
		{
			return type.Namespace.EndsWith("Messages");
		}

		public override string GetExchangeName(Type type)
		{
			return type.Name + "-exchange";
		}
	}

In this case, the convention registers all types within namespaces ending in "Messages" for publication and uses the name of each message type (e.g. "StatusUpdate") with a "-exchange" suffix as the name of the exchange. All other settings are taken from a provided PublishConfigurationConventionBase type which supplies sensible defaults.

Consume Configuration Conventions

To configure RabbitBus to automatically register message types for consumption, the AutoConfigurationModelBuilder type is used to denote the assemblies to scan along with the IConsumeConfigurationConvention instances to use. The following example scans the current assembly for messages which are matched by a MyConsumeConfigurationConvention type:

_bus = new BusBuilder()
	.Configure(new AutoConfigurationModelBuilder()
		.WithAssembly(Assembly.GetExecutingAssembly())
		.WithConsumeConfigurationConvention(new MyConsumeConfigurationConvention())
		.Build())
.Build();

The MyConsumeConfigurationConvention type in the above example might be implemented as follows:

	public class MyConsumeConfigurationConvention : ConsumeConfigurationConventionBase
	{
		public override bool ShouldRegister(Type type)
		{
			return type.Namespace.EndsWith("Messages");
		}

		public override string GetExchangeName(Type type)
		{
			return type.Name + "-exchange";
		}

		public override string GetQueueName(Type type)
		{
			return type.Name + "-queue";
		}
	}

In this case, the convention registers all types within namespaces ending in "Messages" for consumption and uses the name of each message type (e.g. "StatusUpdate") with a suffix of "-exchange" and "-queue" as the name of the exchange and queue respectively. All other settings are taken from a provided ConsumeConfigurationConventionBase type which supplies sensible defaults.

Subscribe Conventions

To configure RabbitBus to automatically register subscription handlers for published message types, the AutoConfigurationModelBuilder type is used to denote the assemblies to scan along with the ISubscriptionConvention instances to use. The following example registers handlers from the calling assembly using the RabbitBus.Configuration.MessageHandlerSubscriptionConvention provided by RabbitBus:

_bus = new BusBuilder()
	.Configure(new AutoConfigurationModelBuilder()
		.WithCallingAssembly()		
		.WithSubscriptionConvention(new MessageHandlerSubscrptionConvention())
		.Build())
.Build();

In the example above, the MessageHandlerSubscrptionConvention type is used to automatically registers types implementing RabbitBus.IMessageHandler<TMessage>.

The following is an example handler for a StatusUpdate message:

	public class StatusUpdateHandler : IMessageHandler<StatusUpdate>
	{
		public void Handle(IMessageContext<StatusUpdate> messageContext)
		{
			// handle message
		}
	}