消息队列-zmq常用通信模式

zmq是一个消息队列。可以在进程内、进程间、TCP、多播中，以消息为单位传输数据，而不是socket的字节流。官方主页上有下载、使用、文档，蛮全的。

常用模式有：Request-Reply，Publish-Subscribe，Parallel Pipeline。

Request-Reply

request

zmq::context_t context (1);zmq::socket_t socket (context, ZMQ_REQ);//Send the requestzmq::message_t request(6);memcpy ((void *)request.data(), "Hello", 5);socket.send(request);//Get the replyzmq::message_t reply;socket.recv(&reply);

server

zmq::context_t context (1);zmq::socket_t socket(context, ZMQ_REP);socket.bind ("tcp://*:5555");while (true) {  zmq::message_t request;  //  Wait for next request from client  socket.recv (&request);  std::cout << "Received Hello" << std::endl;  //  Do some 'work'  sleep (1);  //  Send reply back to client  zmq::message_t reply (5);  memcpy ((void *) reply.data (), "World", 5);  socket.send (reply);}

Publish-Subscribe

publisher

zmq::context_t context (1);zmq::socket_t publisher (context, ZMQ_PUB);publisher.bind("tcp://*:5556");publisher.send(message);

subscriber

zmq::context_t context (1);zmq::socket_t subscriber (context, ZMQ_SUB);subscriber.connect("tcp://localhost:5556");const char *filter = "";subscriber.setsockopt(ZMQ_SUBSCRIBE, filter, strlen (filter));zmq::message_t update;subscriber.recv(&update);

Parallel Pipeline

ventilator

zmq::context_t context (1);//  Socket to send messages onzmq::socket_t  sender(context, ZMQ_PUSH);sender.bind("tcp://*:5557");//  通知sink开始处理任务zmq::socket_t sink(context, ZMQ_PUSH);sink.connect("tcp://localhost:5558");zmq::message_t message(2);memcpy(message.data(), "0", 1);sink.send(message);//开始往pipeline发送数据message.rebuild(10);sprintf ((char *) message.data(), "%d", workload);sender.send(message);    

worker

zmq::context_t context(1);//  Socket to receive messages onzmq::socket_t receiver(context, ZMQ_PULL);receiver.connect("tcp://localhost:5557");//  Socket to send messages tozmq::socket_t sender(context, ZMQ_PUSH);sender.connect("tcp://localhost:5558");//  Process tasks foreverwhile (1) {  receiver.recv(&message);  //  Send results to sink  message.rebuild();  sender.send(message);}

sink

//  Prepare our context and socketzmq::context_t context(1);zmq::socket_t receiver(context,ZMQ_PULL);receiver.bind("tcp://*:5558");//  Wait for start of batchzmq::message_t message;receiver.recv(&message);//receive from workerreceiver.recv(&message);