Extend interface to enable message broadcasting

AdvancedSystems.Core.Abstractions/IMessageBus.cs

@@ -1,15 +1,43 @@
 using System;
+using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Channels;
 using System.Threading.Tasks;
 
 namespace AdvancedSystems.Core.Abstractions;
 
 /// <summary>
-///     Defines an in-memory message bus for publishing and subscribing to messages of type <see cref="IMessage"/>.
+///     Defines an in-memory message bus for publishing and subscribing to messages of type <see cref="IMessage"/> via broadcasts.
 /// </summary>
 public interface IMessageBus : IAsyncDisposable
 {
+    /// <summary>
+    ///     Registers a new channel with the specified channel name and optional topic.
+    /// </summary>
+    /// <param name="channelName">
+    ///     The name of the channel to register.
+    /// </param>
+    /// <param name="topic">
+    ///     An optional topic associated with the channel. If not provided, the default topic will be used.
+    /// </param>
+    /// <returns>
+    ///     Returns <c>true</c> if the channel is successfully registered; otherwise, <c>false</c> if a
+    ///     channel with the same name already exists.
+    /// </returns>
+    bool Register(string channelName, string? topic = default);
+
+    /// <summary>
+    ///     Unregisters the channel with the specified channel name and optional topic.
+    /// </summary>
+    /// <param name="channelName">
+    ///     The name of the channel to unregister.
+    /// </param>
+    /// <returns>
+    ///     Returns <c>true</c> if the channel is successfully unregistered; otherwise, <c>false</c> if
+    ///     no channel with the specified name exists.
+    /// </returns>
+    bool Unregister(string channelName);
+
     /// <summary>
     ///     Publishes a message to the message bus.
     /// </summary>
@@ -19,6 +47,10 @@ public interface IMessageBus : IAsyncDisposable
     /// <param name="message">
     ///     The message to be published.
     /// </param>
+    /// <param name="topic">
+    ///     An optional topic used to filter which channels are meant to receive the message. If not provided,
+    ///     the default topic will be used.
+    /// </param>
     /// <param name="cancellationToken">
     ///     Propagates notification that operations should be cancelled.
     /// </param>
@@ -28,27 +60,35 @@ public interface IMessageBus : IAsyncDisposable
     /// <remarks>
     ///     This method is used to send messages to the bus. Subscribers will receive these messages asynchronously.
     /// </remarks>
-    ValueTask PublishAsync<T>(T message, CancellationToken cancellationToken = default) where T : class, IMessage;
+    /// <exception cref="InvalidOperationException">
+    ///     Thrown when no channels with the specified topic are registered before attempting to publish a message.
+    /// </exception>
+    ValueTask PublishAsync<T>(T message, string? topic = default, CancellationToken cancellationToken = default) where T : class, IMessage;
 
     /// <summary>
     ///     Subscribes to messages of type <typeparamref name="T"/> from the message bus.
     /// </summary>
     /// <typeparam name="T">
     ///     The type of the message to subscribe to. Must implement <see cref="IMessage"/>.
     /// </typeparam>
+    /// <param name="channelName">
+    ///     The name of the channel to subscribe to.
+    /// </param>
+    /// <param name="topic">
+    ///     An optional topic to filter messages. If not provided, the default topic will be used.
+    /// </param>
     /// <param name="cancellationToken">
     ///     Propagates notification that operations should be cancelled.
     /// </param>
     /// <returns>
     ///     This method is used to receive messages of the specified type from the bus. If no messages
     ///     of the type are currently available, it will wait until one becomes available.
     /// </returns>
-    /// <exception cref="InvalidCastException">
-    ///     Thrown when a message retrieved from the channel cannot be cast to the type <typeparamref name="T"/>.
+    /// <exception cref="KeyNotFoundException">
+    ///     Thrown when no channel with the specified name is found.
     /// </exception>
     /// <exception cref="ChannelClosedException">
-    ///     Thrown when the channel is closed and no more messages are available. This indicates that the channel
-    ///     has been marked as complete and will not accept any more messages.
+    ///     Thrown if the channel is closed before a message can be received.
     /// </exception>
-    ValueTask<T> SubscribeAsync<T>(CancellationToken cancellationToken = default) where T : class, IMessage;
+    ValueTask<T> SubscribeAsync<T>(string channelName, string? topic = default, CancellationToken cancellationToken = default) where T : class, IMessage;
 }