SwitchSoftware.Messaging.RPC.RabbitMQ 8.0.6

Switch Software RPC implementation for RabbitMQ

⚠️ Important: Versions 8.0.4 and 8.0.5 contain a channel-leak regression in RpcClient that causes RabbitMQ.Client.Exceptions.ChannelAllocationException (The connection cannot support any more channels) under sustained RPC load. Please upgrade to 8.0.6 or later. See the CHANGELOG for details.

Installation

nuget repo : https://www.nuget.org/packages/SwitchSoftware.Messaging.RPC.RabbitMQ

There are also versions for .net core 6.0 and 5.0

Usage

Instantatiate an RPCServer to listen on "myQueue" and handle requests in the handlerequest method:

    _rpcServer.Start();

    private async Task<string> handleRequest(string data)
    {
        //handle your request
        return $"Hello, you sent me {data}";
    }

You will need to pass an IConfiguration and ILogger instances as well.

Configuration

The server relies on the following app settings (adjust to your RabbitMQ instance):

"RabbitMqConnection": {
  "HostName": "localhost",
  "UserName": "guest",
  "Password": "guest",
  "VirtualHost": "/",
  "Port": "5672",
  "RPC_CLIENT_TIME_OUT_IN_MILLISECONDS": "60000"
}

Note: Port and RPC_CLIENT_TIME_OUT_IN_MILLISECONDS are optional. The default timeout is 45 000 ms.

⚠️ Breaking change from 8.0.3-alpha: The config key was renamed from Username to UserName (capital N). Update your appsettings.json accordingly.

RPC Client

To send a request to the server, instantiate an RPCClient through the RpcClientFactory and call the CallAsync method:

var rpcClientFactory = new RpcClientFactory(configuration, logger);
var rpcClient = rpcClientFactory.GetRpcClient();
var response = await rpcClient.CallAsync("testqueue", "Hello!");

The client also relies on the RabbitMqConnection app settings.

Dead-letter exchange (recommended for 8.0.4+)

Starting in 8.0.4, failed messages are rejected with requeue: false instead of being re-enqueued. Configure a dead-letter exchange so those messages are not silently dropped:

"RabbitMqConnection": {
  "HostName": "localhost",
  "UserName": "guest",
  "Password": "guest",
  "VirtualHost": "/"
}

Declare the DLX on the RabbitMQ broker before starting the server:

rabbitmqadmin declare exchange name=dlx type=direct
rabbitmqadmin declare queue name=myQueue.failed
rabbitmqadmin declare binding source=dlx destination=myQueue.failed routing_key=myQueue

Then declare your server queue with the DLX argument:

// When constructing RpcServer the queue is declared internally.
// To attach a DLX, pre-declare the queue on the broker with:
//   x-dead-letter-exchange = dlx
//   x-dead-letter-routing-key = myQueue

Release Changes

• Fixed ChannelAllocationException regression introduced in 8.0.4:
  • RpcClient no longer over-releases its concurrency semaphore when WaitAsync is cancelled, which previously allowed unbounded concurrent channel creation on the underlying connection.
  • RpcClient now cancels the reply-queue consumer (BasicCancel) before returning a channel to the pool, preventing accumulation of dead consumers and orphaned exclusive auto-delete reply queues on pooled channels.
• Channel pooling behavior is preserved.

Version History