zmq_socket()

Name

zmq_socket : 创建0MQ socket

Synopsis

void *zmq_socket(void *context, int type)

描述

zmq_socket(): 在一个特定的context中创建一个0MQ socket，返回一个不透明的句柄到新创建的socket中。

type: 指定socket类型。

新创建的socket初试时时未绑定的，不和任何相关联。为了建立一个信息流，socket必须首先zmq_connect()其中一个终端，或是zmq_bind();

与传统socket的不同：

传统socket提供的同步接口，要么是面向连接的可靠的字节流(SOCK_STREAM)，要么是无连接不可靠的数据包（SOCK_DGRAM）.

0MQ socket 是异步的，物理连接的安装和卸载，重连和有效地转发等对用户来说都是透明的，时间由0MQ自己控制。 消息会排队，当一个peer不能有效接收时。

传统socket ：严格的1-1(2个peer）、N-1（多个client，一个server）、1-N（多播）。

0MQ: ZMQ_PAIR是个特例。0MQ socket 可以连接到多个终端，使用zmq_connect();同时，可以结果多个终端的信息，使用zmq_bind().  N-N的模式

线程安全：

0MQ socket不是线程安全的。 Applications MUST NOT use a socket from multiple threads except after migrating a socket from one thread to another with a "full fence" memory barrier.

Socket类型

1. Request-reply pattern:

   Summary of ZMQ_REQ characteristics
   Compatible peer sockets	ZMQ_REP, ZMQ_ROUTER
   Direction	Bidirectional
   Send/receive pattern	Send, Receive, Send, Receive, …
   Outgoing routing strategy	Round-robin
   Incoming routing strategy	Last peer
   Action in mute state	Block

   Summary of ZMQ_REP characteristics
   Compatible peer sockets	ZMQ_REQ, ZMQ_DEALER
   Direction	Bidirectional
   Send/receive pattern	Receive, Send, Receive, Send, …
   Incoming routing strategy	Fair-queued
   Outgoing routing strategy	Last peer
   Action in mute state	Drop

   Summary of ZMQ_DEALER characteristics
   Compatible peer sockets	ZMQ_ROUTER, ZMQ_REP, ZMQ_DEALER
   Direction	Bidirectional
   Send/receive pattern	Unrestricted
   Outgoing routing strategy	Round-robin
   Incoming routing strategy	Fair-queued
   Action in mute state	Block

   
   

   Summary of ZMQ_ROUTER characteristics
   Compatible peer sockets	ZMQ_DEALER, ZMQ_REQ, ZMQ_ROUTER
   Direction	Bidirectional
   Send/receive pattern	Unrestricted
   Outgoing routing strategy	See text
   Incoming routing strategy	Fair-queued
   Action in mute state	Drop

   Summary of ZMQ_DEALER characteristics
   Compatible peer sockets	ZMQ_ROUTER, ZMQ_REP, ZMQ_DEALER
   Direction	Bidirectional
   Send/receive pattern	Unrestricted
   Outgoing routing strategy	Round-robin
   Incoming routing strategy	Fair-queued
   Action in mute state	Block

   
   
2. Publish-subscribe pattern : 1-N （1 publisher，multiple subscribers

1. Summary of ZMQ_XSUB characteristics
   Compatible peer sockets	ZMQ_PUB, ZMQ_XPUB
   Direction	Unidirectional
   Send/receive pattern	Receive messages, send subscriptions
   Incoming routing strategy	Fair-queued
   Outgoing routing strategy	N/A
   Action in mute state	Drop

   Summary of ZMQ_SUB characteristics
   Compatible peer sockets	ZMQ_PUB, ZMQ_XPUB
   Direction	Unidirectional
   Send/receive pattern	Receive only
   Incoming routing strategy	Fair-queued
   Outgoing routing strategy	N/A
   Action in mute state	Drop

   Summary of ZMQ_PUB characteristics
   Compatible peer sockets	ZMQ_SUB, ZMQ_XSUB
   Direction	Unidirectional
   Send/receive pattern	Send only
   Incoming routing strategy	N/A
   Outgoing routing strategy	Fan out
   Action in mute state	Drop

   Summary of ZMQ_XPUB characteristics
   Compatible peer sockets	ZMQ_SUB, ZMQ_XSUB
   Direction	Unidirectional
   Send/receive pattern	Send messages, receive subscriptions
   Incoming routing strategy	N/A
   Outgoing routing strategy	Fan out
   Action in mute state	Drop

2. pipeline pattern：ZMQ_PUSH、ZMQ_PULL

   Summary of ZMQ_PUSH characteristics
   Compatible peer sockets	ZMQ_PULL
   Direction	Unidirectional
   Send/receive pattern	Send only
   Incoming routing strategy	N/A
   Outgoing routing strategy	Round-robin
   Action in mute state	Block

Summary of ZMQ_PULL characteristics
Compatible peer sockets	ZMQ_PUSH
Direction	Unidirectional
Send/receive pattern	Receive only
Incoming routing strategy	Fair-queued
Outgoing routing strategy	N/A
Action in mute state	Block