Asynchronous Command/Query library

This library contains interfaces used to be able to use messaging (commands, queries and events) in applications without tightly coupling it to a specific implementation.

Example

Define a message:

public class ActivateAccount
{
	public int AccountId {get; set; }
	public string ActivationKey { get; set; }
}

Invoke it:

var msg = new ActivateAccount { AccountId = 35, ActivationKey = "dfkldsie93kcn22" };
await _messageBus.SendAsync(msg);

Handle it:

public class ActivateAccountHandler : IMessageHandler<ActivateAccount>
{
    private readonly IAccountRepository _repository;
	
	public ActivateAccountHandler(IAccountRepository repository)
	{
		if (repository == null) throw new ArgumentNullException(repository);
		
		_repository = repository;
	}
	
	public async Task HandleAsync(IMessageContext context, ActivateAccount message)
	{
		var user = await _repository.Get(message.AccountId);
		user.Activate(message.ActivationKey);
		await _repository.UpdateAsync(user);
		
		await context.SendAsync(new AccountActivated(message.AccountId));
	}
}

Message handlers are fully isolated from the rest of the specification and therefore easy to test and maintain.

Implementations

The following implementations exist.

Bus

The MessageBus and QueryBus currently have the following implementations:

• DependenyInjection: Use your favorite container to execute and queue messages.
• Microsoft.Extensions.DependencyInjection: Currently under implementation
• Griffin.Container: Currently under implementation

Queues

• ADO.NET: Uses a table in your database to enqueue and dequeue messages (to get persistance).
• Azure ServiceBus: Under development