无法在ZMQ

Question

发送capnp消息我有下面的代码，我想送过来ZMQ一个capnp消息：

::capnp::MallocMessageBuilder message;  
Guitar::Builder guitar = message.initRoot<Guitar>(); 
guitar.setModel(1); 
guitar.setPrice(1200); 

kj::Array<capnp::word> words = messageToFlatArray(message); 

_publisher.send(words); 

我使用的是发布 - 订阅模式&我收到以下错误：

error: no matching member function for call to 
     'send' 
     _publisher.send(words); 
     ~~~~~~~~~~~^~~~ /usr/local/include/zmq.hpp:610:21: note: candidate function not viable: no known conversion from 
'kj::Array<capnp::word>' to 
     'zmq::message_t &' for 1st argument 
     inline bool send (message_t &msg_, int flags_ = 0) 
        ^/usr/local/include/zmq.hpp:627:21: note: candidate function not viable: no known conversion from 
'kj::Array<capnp::word>' to 
     'zmq::message_t' for 1st argument 
     inline bool send (message_t &&msg_, int flags_ = 0) 
        ^/usr/local/include/zmq.hpp:620:35: note: candidate function template not viable: requires at least 2 arguments, 
but 1 was 
     provided 
     template<typename I bool send(I first, I last, int flags_=0) 
           ^/usr/local/include/zmq.hpp:600:23: note: candidate function not viable: requires at least 2 arguments, 
but 1 was provided 
     inline size_t send (const void *buf_, size_t len_, int flags_ = 0) 

Answer 1

我没有用过zeromq，而我才刚刚开始使用capnp，但我真的很喜欢简单说capnp带给通过套接字发送数据。

我会用capnp functions在zeromq发送和接收数据时，这些数据是由capnp，如果你还可以连载：

capnp::writeMessageToFd(fd, builder)

其中fd是插座和builder是你的建设者：message

在接收端，您可以用类似capnp::StreamFdMessageReader message(socket)

等待它如果你真的想要把这个东西打包成一个zeromq可以采用的格式，或许将这个数组转换为字节，详见here，这对你的zeromq消息的构造函数是可以接受的。

祝你好运！

Answer 2

kj::ArrayPtr来自KJ图书馆，它是Cap'n Proto的一部分。 ZeroMQ对KJ一无所知，所以不会识别这种类型。它要么需要message_t（ZeroMQ类型）或指针/大小组合。你可以这样做：

auto bytes = words.asBytes(); 
_publisher.send(bytes.begin(), bytes.size());