Implement Direct Reply-To. Rename RpcClient/RpcServer to Requester/Responder (#135)

* This PR renames RPC-related classes and interfaces to more descriptive names (RpcClient/RpcServer → Requester/Responder) and adds support for RabbitMQ's DirectReply-To feature for improved RPC performance. The DirectReply-To feature allows the server to send replies directly to clients without creating explicit reply queues when supported by RabbitMQ 4.2+.

* Fixes #133

---------

Signed-off-by: Gabriele Santomaggio <[email protected]>
Co-authored-by: Copilot <[email protected]>

Author: Gsantomaggio

.ci/ubuntu/cluster/gha-setup.sh

@@ -19,7 +19,7 @@ function run_docker_compose
     docker compose --file "$script_dir/docker-compose.yml" $@
 }
 
-readonly rabbitmq_image="${RABBITMQ_IMAGE:-rabbitmq:4.2-rc-management}"
+readonly rabbitmq_image="${RABBITMQ_IMAGE:-rabbitmq:4.2-management}"
 
 if [[ ! -v GITHUB_ACTIONS ]]
 then

.ci/ubuntu/cluster/rmq/Dockerfile

@@ -1,4 +1,4 @@
-ARG RABBITMQ_DOCKER_TAG=rabbitmq:4.1.0-beta.4-management-alpine
+ARG RABBITMQ_DOCKER_TAG=rabbitmq:4.2-management-alpine
 
 FROM ${RABBITMQ_DOCKER_TAG}
 

.ci/ubuntu/one-node/gha-setup.sh

@@ -9,7 +9,7 @@ readonly script_dir
 echo "[INFO] script_dir: '$script_dir'"
 
 
-readonly rabbitmq_image="${RABBITMQ_IMAGE:-rabbitmq:4.2-rc-management}"
+readonly rabbitmq_image="${RABBITMQ_IMAGE:-rabbitmq:4.2-management}"
 
 
 

.ci/windows/versions.json

@@ -1,4 +1,4 @@
 {
   "erlang": "27.2",
-  "rabbitmq": "4.1.0"
+  "rabbitmq": "4.2.0"
 }

RabbitMQ.AMQP.Client/FeatureFlags.cs

@@ -24,6 +24,13 @@ public class FeatureFlags
         /// </summary>
         public bool IsBrokerCompatible { get; internal set; } = false;
 
+        /// <summary>
+        /// Check if Direct Reply-To is supported.
+        /// Direct Reply-To is available in RabbitMQ 4.2 and later.
+        /// see: https://www.rabbitmq.com/docs/direct-reply-to
+        /// </summary>
+        public bool IsDirectReplyToSupported { get; internal set; } = false;
+
         public void Validate()
         {
             if (!IsBrokerCompatible)

RabbitMQ.AMQP.Client/IConnection.cs

@@ -28,16 +28,16 @@ public interface IConnection : ILifeCycle
         IConsumerBuilder ConsumerBuilder();
 
         /// <summary>
-        /// Create an <see cref="IRpcServerBuilder"/> instance for this connection.
+        /// Create an <see cref="IResponderBuilder"/> instance for this connection.
         /// </summary>
-        /// <returns><see cref="IRpcServerBuilder"/> instance for this connection.</returns>
-        IRpcServerBuilder RpcServerBuilder();
+        /// <returns><see cref="IResponderBuilder"/> instance for this connection.</returns>
+        IResponderBuilder ResponderBuilder();
 
         /// <summary>
-        /// Create an <see cref="IRpcClientBuilder"/> instance for this connection.
+        /// Create an <see cref="IRequesterBuilder"/> instance for this connection.
         /// </summary>
-        /// <returns><see cref="IRpcClientBuilder"/> instance for this connection.</returns>
-        IRpcClientBuilder RpcClientBuilder();
+        /// <returns><see cref="IRequesterBuilder"/> instance for this connection.</returns>
+        IRequesterBuilder RequesterBuilder();
 
         /// <summary>
         /// Get the properties for this connection.

RabbitMQ.AMQP.Client/IConsumer.cs

@@ -37,6 +37,13 @@ public interface IConsumer : ILifeCycle
         /// Returns the number of unsettled messages.
         /// </summary>
         long UnsettledMessageCount { get; }
+
+        /// <summary>
+        /// Returns queue name the consumer is consuming from.
+        /// The Queue name is usually configured by the user via the <see cref="IConsumerBuilder"/>,
+        /// but can also be generated by the client the special direct-reply-to queue.
+        /// </summary>
+        string Queue { get; }
     }
 
     public interface IContext

RabbitMQ.AMQP.Client/IConsumerBuilder.cs

@@ -19,7 +19,17 @@ public enum StreamOffsetSpecification
     public interface IConsumerBuilder
     {
         IConsumerBuilder Queue(IQueueSpecification queueSpecification);
-        IConsumerBuilder Queue(string queueName);
+        IConsumerBuilder Queue(string? queueName);
+
+        /// <summary>
+        /// If direct reply-to is enabled, the client will use the direct reply-to feature of AMQP 1.0.
+        /// The server must also support direct reply-to.
+        /// This feature allows the server to send the reply directly to the client without going through a reply queue.
+        /// This can improve performance and reduce latency.
+        /// Default is false.
+        /// https://www.rabbitmq.com/docs/direct-reply-to
+        /// </summary>
+        IConsumerBuilder DirectReplyTo(bool directReplyTo);
 
         IConsumerBuilder MessageHandler(MessageHandler handler);
 

RabbitMQ.AMQP.Client/IRpcClient.cs renamed to RabbitMQ.AMQP.Client/IRequester.cs

@@ -8,34 +8,33 @@
 
 namespace RabbitMQ.AMQP.Client
 {
-
-    public interface IRpcClientAddressBuilder : IAddressBuilder<IRpcClientAddressBuilder>
+    public interface IRequesterAddressBuilder : IAddressBuilder<IRequesterAddressBuilder>
     {
-        IRpcClientBuilder RpcClient();
+        IRequesterBuilder Requester();
     }
 
     /// <summary>
     /// IRpcClientBuilder is the interface for creating an RPC client.
-    /// See also <seealso cref="IRpcClient"/> and <seealso cref="IRpcServerBuilder"/>
+    /// See also <seealso cref="IRequester"/> and <seealso cref="IResponderBuilder"/>
     /// </summary>
-    public interface IRpcClientBuilder
+    public interface IRequesterBuilder
     {
         /// <summary>
         /// Request address where the client sends requests.
         /// The server consumes requests from this address.
         /// </summary>
         /// <returns></returns>
-        IRpcClientAddressBuilder RequestAddress();
+        IRequesterAddressBuilder RequestAddress();
 
         /// <summary>
         /// The queue from which requests are consumed.
         /// if not set the client will create a temporary queue.
         /// </summary>
         /// <param name="replyToQueueName"> The queue name</param>
         /// <returns></returns>
-        IRpcClientBuilder ReplyToQueue(string replyToQueueName);
+        IRequesterBuilder ReplyToQueue(string replyToQueueName);
 
-        IRpcClientBuilder ReplyToQueue(IQueueSpecification replyToQueue);
+        IRequesterBuilder ReplyToQueue(IQueueSpecification replyToQueue);
 
         /// <summary>
         /// Extracts the correlation id from the request message.
@@ -45,7 +44,7 @@ public interface IRpcClientBuilder
         /// </summary>
         /// <param name="correlationIdExtractor"></param>
         /// <returns></returns>
-        IRpcClientBuilder CorrelationIdExtractor(Func<IMessage, object>? correlationIdExtractor);
+        IRequesterBuilder CorrelationIdExtractor(Func<IMessage, object>? correlationIdExtractor);
 
         /// <summary>
         /// Post processes the reply message before sending it to the server.
@@ -56,7 +55,7 @@ public interface IRpcClientBuilder
         /// </summary>
         /// <param name="requestPostProcessor"></param>
         /// <returns></returns>
-        IRpcClientBuilder RequestPostProcessor(Func<IMessage, object, IMessage>? requestPostProcessor);
+        IRequesterBuilder RequestPostProcessor(Func<IMessage, object, IMessage>? requestPostProcessor);
 
         /// <summary>
         /// Client and Server must agree on the correlation id.
@@ -66,27 +65,27 @@ public interface IRpcClientBuilder
         /// </summary>
         /// <param name="correlationIdSupplier"></param>
         /// <returns></returns>
-
-        IRpcClientBuilder CorrelationIdSupplier(Func<object>? correlationIdSupplier);
+        IRequesterBuilder CorrelationIdSupplier(Func<object>? correlationIdSupplier);
 
         /// <summary>
         /// The time to wait for a reply from the server.
         /// </summary>
         /// <param name="timeout"></param>
         /// <returns></returns>
-        IRpcClientBuilder Timeout(TimeSpan timeout);
+        IRequesterBuilder Timeout(TimeSpan timeout);
+
         /// <summary>
         ///  Build and return the RPC client.
         /// </summary>
         /// <returns></returns>
-        Task<IRpcClient> BuildAsync();
+        Task<IRequester> BuildAsync();
     }
 
     /// <summary>
     ///  IRpcClient is the interface for an RPC client.
-    /// See also <seealso cref="IRpcServer"/> and <seealso cref="IRpcClientBuilder"/>
+    /// See also <seealso cref="IResponder"/> and <seealso cref="IRequesterBuilder"/>
     /// </summary>
-    public interface IRpcClient : ILifeCycle
+    public interface IRequester : ILifeCycle
     {
         /// <summary>
         /// PublishAsync sends a request message to the server and blocks the thread until the response is received.
@@ -98,5 +97,14 @@ public interface IRpcClient : ILifeCycle
         /// <param name="cancellationToken">Cancellation token</param>
         /// <returns></returns>
         Task<IMessage> PublishAsync(IMessage message, CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// The ReplyTo queue address can be created by:
+        /// - the client providing a specific queue name
+        /// - the client creating a temporary queue
+        /// - The server uses this address to send the reply message. with direct-reply-to
+        /// </summary>
+        /// <returns></returns>
+        public string GetReplyToQueue();
     }
 }

RabbitMQ.AMQP.Client/IRpcServer.cs renamed to RabbitMQ.AMQP.Client/IResponder.cs

@@ -7,22 +7,22 @@
 
 namespace RabbitMQ.AMQP.Client
 {
-
     /// <summary>
     /// IRpcServerBuilder is the interface for creating an RPC server.
     /// The RPC server consumes requests from a queue and sends replies to a reply queue.
-    /// See also <seealso cref="IRpcServer"/>  and <seealso cref="IRpcClientBuilder"/>
+    /// See also <seealso cref="IResponder"/>  and <seealso cref="IRequesterBuilder"/>
     /// </summary>
-    public interface IRpcServerBuilder
+    public interface IResponderBuilder
     {
         /// <summary>
         /// The queue from which requests are consumed.
         /// The client sends requests to this queue and the server consumes them.
         /// </summary>
         /// <param name="requestQueue"></param>
         /// <returns></returns>
-        IRpcServerBuilder RequestQueue(string requestQueue);
-        IRpcServerBuilder RequestQueue(IQueueSpecification requestQueue);
+        IResponderBuilder RequestQueue(string requestQueue);
+
+        IResponderBuilder RequestQueue(IQueueSpecification requestQueue);
 
         /// <summary>
         /// Extracts the correlation id from the request message.
@@ -32,8 +32,7 @@ public interface IRpcServerBuilder
         /// </summary>
         /// <param name="correlationIdExtractor"></param>
         /// <returns></returns>
-
-        IRpcServerBuilder CorrelationIdExtractor(Func<IMessage, object>? correlationIdExtractor);
+        IResponderBuilder CorrelationIdExtractor(Func<IMessage, object>? correlationIdExtractor);
 
         /// <summary>
         /// Post processes the reply message before sending it to the client.
@@ -44,38 +43,37 @@ public interface IRpcServerBuilder
         /// </summary>
         /// <param name="replyPostProcessor"></param>
         /// <returns></returns>
-        IRpcServerBuilder ReplyPostProcessor(Func<IMessage, object, IMessage>? replyPostProcessor);
+        IResponderBuilder ReplyPostProcessor(Func<IMessage, object, IMessage>? replyPostProcessor);
 
         /// <summary>
         /// Handle the request message and return the reply message.
         /// </summary>
         /// <param name="handler"></param>
         /// <returns></returns>
-        IRpcServerBuilder Handler(RpcHandler handler);
+        IResponderBuilder Handler(RpcHandler handler);
 
         /// <summary>
         /// Build and return the RPC server.
         /// </summary>
         /// <returns></returns>
-        Task<IRpcServer> BuildAsync();
+        Task<IResponder> BuildAsync();
     }
 
     /// <summary>
     /// Event handler for handling RPC requests.
     /// </summary>
     // TODO cancellation token
-    public delegate Task<IMessage> RpcHandler(IRpcServer.IContext context, IMessage request);
+    public delegate Task<IMessage> RpcHandler(IResponder.IContext context, IMessage request);
 
     /// <summary>
-    /// IRpcServer interface for creating an RPC server.
+    /// IResponder interface for creating an RPC server.
     /// The RPC is simulated by sending a request message and receiving a reply message.
     /// Where the client sends the queue where wants to receive the reply.
     /// RPC client ---> request queue ---> RPC server ---> reply queue ---> RPC client
-    /// See also <seealso cref="IRpcClient"/>
+    /// See also <seealso cref="IRequester"/>
     /// </summary>
-    public interface IRpcServer : ILifeCycle
+    public interface IResponder : ILifeCycle
     {
-
         public interface IContext
         {
             IMessage Message(byte[] body);