VL.Messaging.Abstraction 1.1.2

Abstraction Messaging

This package contains the abstraction for potenital message brokers.

Getting Started

1. Install package VL.Messaging.Abstraction

   dotnet add package VL.Messaging.Abstraction
   

2. Interfaces

   public interface IMessageConsumer
   {
       public Task ConsumeAsync(CancellationToken cancellationToken = default);
   }
   
   public interface IMessageHandler<in TMessage> : IMessageHandler where TMessage : Message, new()
   {
       public Task HandleAsync(TMessage message, CancellationToken cancellationToken = default);
   }
   
   public interface IMessageHandlerDescriptor
   {
       public Type MessageType { get; }
   
       public IMessageHandler GetMessageHandler();
   }
   
   public interface IMessagePublisher<in TMessage> where TMessage : Message, new()
   {
       public Task PublishAsync(TMessage message);
   }
   

3. Classes

   public abstract class Message
   {
       protected Message() : this(Guid.NewGuid(), DateTimeOffset.UtcNow) { }
   
       protected Message(Guid id, DateTimeOffset creationDate)
       {
           Id = id;
           CreationDate = creationDate;
       }
   
       public Guid Id { get; }
   
       public DateTimeOffset CreationDate { get; }
   
       public string Source { get; set; } = "DefaultSource";
   };
   
   public abstract class MessageHandlerBase<TMessage> 
       : IMessageHandler<TMessage> where TMessage : Message, new()
   {
       public abstract Task HandleAsync(TMessage message, CancellationToken cancellationToken = default);
   
       public Task HandleAsync(Message message, CancellationToken cancellationToken = default)
       {
           if (message is null)
           {
               throw new ArgumentNullException(nameof(message));
           }
   
           if (message is TMessage specificMessage)
           {
               return HandleAsync(specificMessage, cancellationToken);
           }
   
           throw new InvalidOperationException("Invalid message type." +
               $"Expected type \"{typeof(TMessage).Name}\" instead of \"{message.GetType().Name}\".");
     }
   }
   
   public class MessageHandlerDescriptor<TMessage> 
       : IMessageHandlerDescriptor where TMessage : Message, new()
   {
       private readonly Func<IMessageHandler> _factory;
   
       public MessageHandlerDescriptor(Func<IMessageHandler<TMessage>> factory)
       {
           MessageType = typeof(TMessage);
           _factory = factory ?? throw new ArgumentNullException(nameof(factory));
       }
   
       public Type MessageType { get; }
   
       public IMessageHandler GetMessageHandler()
       {
           return _factory();
       }
   }