castle.zmq

Modern and robust .net binding for 0mq (zmq). From the http://www.castleproject.org/ people.

Why

The existing bindings for .net are either staled or not really built for real world usage. Out of need, we had to create a new one.

Notes

• The libzmq.dll included has been compiled with FD_SETSIZE=2400. The default (winsock) config is 64
• You must use the correct dll and libzmq for your processor architecture (or, for the hosting process). In other words, if the hosting process is x86, use the x86. Otherwise x64. If you don't, expect BadImageFormatException

Using it

First of all, be familiar with zmq. Read its fantastic amazing guide & check their api.

Before using it, initiate a context.

using Castle.Zmq;
... 
var ctx = new Context();
...
// some serious profitable work here
...
ctx.Dispose();

Multipart messages

Use the hasMoreToSend which internally is mapped to SNDMORE

socket.Send(byteBuffer1, hasMoreToSend: true);
socket.Send(byteBuffer2, hasMoreToSend: true);
socket.Send(finalBuffer); // no flag

On the receiving side, you can check if there's more to be received:

var data1 = subSocket.Recv();
if (subSocket.HasMoreToRecv()) 
{
	var data2 = subSocket.Recv(); 
}

Req/Rep

const string MsgReq = "Hello";
const string MsgReply = "World";

using (var reqSocket = base.Context.CreateSocket(SocketType.Req))
using (var repSocket = base.Context.CreateSocket(SocketType.Rep))
{
	repSocket.Bind("tcp://0.0.0.0:90002");

	reqSocket.Connect("tcp://127.0.0.1:90002");

	reqSocket.Send(MsgReq);

	var msg = repSocket.Recv();
	var msgStr = Encoding.UTF8.GetString(msg);

	repSocket.Send(MsgReply);

	msg = reqSocket.Recv();
	msgStr = Encoding.UTF8.GetString(msg);
}

Pub/Sub

A publisher should send the topic then send the data. Use the flag to indicate there's more coming:

var pubSocket = base.Context.CreateSocket(SocketType.Pub)

pubSocket.Send("topic", null, hasMoreToSend: true);
pubSocket.Send("data");

The subscriber socket should (duh) subscribe to the topics of interest or all.

var subSocket = base.Context.CreateSocket(SocketType.Sub)

// specific topic
subSocket.Subscribe("topicX");

// everything
subSocket.SubscribeAll();

Note that on the sub side the first Recv will get the topic, the next the actual data.

Polling

Use the Polling class to specify the events and sockets you're interested in polling.

using (var repSocket = base.Context.CreateSocket(SocketType.Rep))
using (var reqSocket = base.Context.CreateSocket(SocketType.Req))
{
	repSocket.Bind("tcp://0.0.0.0:90001");

	var polling = new Polling(PollingEvents.RecvReady, repSocket, reqSocket);

	polling.RecvReady += (socket) =>
	{
		// using socket.Recv() here is guaranted to return stuff
	};
	
	reqSocket.Connect("tcp://127.0.0.1:90001");
	reqSocket.Send("Hello");
	
	polling.PollForever(); // this returns once some socket event happens
}

Monitoring

In progress

Writing test

The Socket and Context use the IZmqContext and IZmqSocket in order to allow you to mock/stub their real implementation.

Additions & Extensions

In progress

Device

WorkerPool

RPC

In progress

How to help

Send a pull request

Contact

Check Castle's Get Involved page.