AxonFlow is a open-source derivate work of MediatR version 12.5.0 with additions to transform message dispatching from in-process to Out-Of-Process messaging via RPC calls implemented with popular message dispatchers.

When you need AxonFlow.

Axon is very good to implement some patterns like CQRS

Implementing CQRS in an in-process application does not bring to you all the power of the pattern but gives you the opportunity to have organized, easy to maintain code. When the application grow you may need to refactor your things to a microservices architecture.

Microservices and patterns like CQRS are very powerfull combination. In this scenario you will need to rewrite communication part to use some kind of out of process message dispatcher.

AxonFlow provides you message dispatching behaviour and let you decide which call needs to be in-process and which needs to be Out-of-process and dispatched remotely, via a configuration without changing a single row of your code.

Installation

You should install AxonFlow with NuGet

Install-Package Axon

if you need out-of-process functions

Install-Package Axon-Flow

Or via the .NET Core command line interface:

dotnet add package Axon
dotnet add package Axon-Flow

Either commands, from Package Manager Console or .NET Core CLI, will download and install AxonFlow and all required dependencies.

Using Contracts-Only Package

To reference only the contracts for AxonFlow, which includes:

IRequest (including generic variants) INotification IStreamRequest Add a package reference to Axon-Contracts

This package is useful in scenarios where your AxonFlow contracts are in a separate assembly/project from handlers. Example scenarios include:

API contracts GRPC contracts Blazor

Basic Configuration using IServiceCollection

Configuring AxonFlow is an easy task.

1. Add AxonFlow to services configuration via AddAxon extension method. this will register the Axon service that can be used for message dispatching.

Axon supports Microsoft.Extensions.DependencyInjection.Abstractions directly. To register various Axon services and handlers:

services.AddAxon(cfg => cfg.RegisterServicesFromAssemblyContaining<Startup>());

or with an assembly:

services.AddAxon(cfg => cfg.RegisterServicesFromAssembly(typeof(Startup).Assembly));

This registers:

• IAxon as transient
• ISender as transient
• IPublisher as transient
• IRequestHandler<,> concrete implementations as transient
• IRequestHandler<> concrete implementations as transient
• INotificationHandler<> concrete implementations as transient
• IStreamRequestHandler<> concrete implementations as transient
• IRequestExceptionHandler<,,> concrete implementations as transient
• IRequestExceptionAction<,>) concrete implementations as transient

This also registers open generic implementations for:

• INotificationHandler<>
• IRequestExceptionHandler<,,>
• IRequestExceptionAction<,>

To register behaviors, stream behaviors, pre/post processors:

services.AddAxon(cfg => {
    cfg.RegisterServicesFromAssembly(typeof(Startup).Assembly);
    cfg.AddBehavior<PingPongBehavior>();
    cfg.AddStreamBehavior<PingPongStreamBehavior>();
    cfg.AddRequestPreProcessor<PingPreProcessor>();
    cfg.AddRequestPostProcessor<PingPongPostProcessor>();
    cfg.AddOpenBehavior(typeof(GenericBehavior<,>));
    });

If no configuration is given for the message dispatched, all messages are dispatched in-process. You can change the default behaviour in using the following configuration

2. Decide what is the default behaviour, available options are
   1. ImplicitLocal : all axon.Send() calls will be delivered in-process unless further configuration.
   2. ImplicitRemote : all axon.Send() calls will be delivered out-of-process unless further configuration.
   3. Explicit : you have the responsability do declare how to manage every single call.

    services.AddAxonFlow(opt =>
    {
      opt.Behaviour = AxonFlowBehaviourEnum.Explicit;
    });

3. Configure calls delivery type according with you behaviour:

    services.AddAxonFlow(opt =>
    {
      opt.Behaviour = AxonFlowBehaviourEnum.Explicit;
      opt.SetAsRemoteRequest<Request1>();
      opt.SetAsRemoteRequest<Request2>();
      ....
    }

Of course you will have some processes with requests declared Local and other processes with same requests declared Remote.

Example of process with all local calls and some remote calls

    services.AddAxonFlow(opt =>
    {
      opt.Behaviour = AxonFlowBehaviourEnum.ImplicitLocal;
      opt.SetAsRemoteRequest<Request1>();
      opt.SetAsRemoteRequest<Request2>();
      opt.SetAsRemoteRequests(typeof(Request2).Assembly); // All requests in an assembly
    });

Example of process with local handlers.

    services.AddAxonFlow(opt =>
    {
      opt.Behaviour = AxonFlowBehaviourEnum.ImplicitLocal;
    });

Example of process with remore handlers.

    services.AddAxonFlow(opt =>
    {
      opt.Behaviour = AxonFlowBehaviourEnum.ImplicitRemote;
    });

AxonFlow with RabbitMQ

Installing AxonFlow RabbitMQ extension.

    Install-Package Axon-Flow-RabbitMQ

Or via the .NET Core command line interface:

    dotnet add package Axon-Flow-RabbitMQ

Configuring RabbitMQ Extension.

Once installed you need to configure rabbitMQ extension.

    services.AddAxonFlowRabbitMQMessageDispatcher(opt =>
    {
      opt.HostName = "rabbit instance";
      opt.Port = 5672;
      opt.Password = "password";
      opt.UserName = "rabbituser";
      opt.VirtualHost = "/";
    });
    services.ResolveAxonFlowCalls();

or if you prefer use appsettings configuration

    services.AddAxonFlowRabbitMQMessageDispatcher(opt => context.Configuration.GetSection("rabbitmq").Bind(opt));
    services.ResolveAxonFlowCalls();

AxonFlow with Kafka

Installing AxonFlow Kafka extension.

    Install-Package Axon-Flow-Kafka

Or via the .NET Core command line interface:

    dotnet add package Axon-Flow-Kafka

Configuring Kafka Extension.

Once installed you need to configure Kafka extension.

    services.AddAxonFlowKafkaMessageDispatcher(opt =>
    {
      opt.BootstrapServers = "localhost:9092";
    });
    services.ResolveAxonFlowCalls();

or if you prefer use appsettings configuration

    services.AddAxonFlowKafkaMessageDispatcher(opt => context.Configuration.GetSection("kafka").Bind(opt));
    services.ResolveAxonFlowCalls();

AxonFlow with Azure Message Queues

Coming soon.