python zeromq
python examples https://github.com/imatix/zguide/tree/master/examples/Pythonhwserver.py
Python代码
[*]#
[*]# Hello World server in Python
[*]# Binds REP socket to tcp://*:5555
[*]# Expects "Hello" from client, replies with "World"
[*]#
[*]import zmq
[*]import time
[*]
[*]context = zmq.Context()
[*]socket = context.socket(zmq.REP)
[*]socket.bind("tcp://*:5555")
[*]
[*]while True:
[*]# Wait for next request from client
[*]message = socket.recv()
[*]print "Received request: ", message
[*]
[*]# Do some 'work'
[*]time.sleep (1) # Do some 'work'
[*]
[*]# Send reply back to client
[*]socket.send("World")
#
# Hello World server in Python
# Binds REP socket to tcp://*:5555
# Expects "Hello" from client, replies with "World"
#
import zmq
import time
context = zmq.Context()
socket = context.socket(zmq.REP)
socket.bind("tcp://*:5555")
while True:
#Wait for next request from client
message = socket.recv()
print "Received request: ", message
#Do some 'work'
time.sleep (1) # Do some 'work'
#Send reply back to client
socket.send("World")
hwclient.py
Python代码
[*]#
[*]# Hello World client in Python
[*]# Connects REQ socket to tcp://localhost:5555
[*]# Sends "Hello" to server, expects "World" back
[*]#
[*]import zmq
[*]
[*]context = zmq.Context()
[*]
[*]# Socket to talk to server
[*]print "Connecting to hello world server..."
[*]socket = context.socket(zmq.REQ)
[*]socket.connect ("tcp://localhost:5555")
[*]
[*]# Do 10 requests, waiting each time for a response
[*]for request in range (1,10):
[*]print "Sending request ", request,"..."
[*]socket.send ("Hello")
[*]
[*]# Get the reply.
[*]message = socket.recv()
[*]print "Received reply ", request, "[", message, "]"
#
# Hello World client in Python
# Connects REQ socket to tcp://localhost:5555
# Sends "Hello" to server, expects "World" back
#
import zmq
context = zmq.Context()
#Socket to talk to server
print "Connecting to hello world server..."
socket = context.socket(zmq.REQ)
socket.connect ("tcp://localhost:5555")
#Do 10 requests, waiting each time for a response
for request in range (1,10):
print "Sending request ", request,"..."
socket.send ("Hello")
#Get the reply.
message = socket.recv()
print "Received reply ", request, "[", message, "]"
问题3：zeroMQ实现一个消息层？
答：
实现一个ZeroMQ消息层需要三个步骤：
1.选择传输协议
0MQ提供了4种不同的传输协议
INPROC an In-Process communication model
IPC an Inter-Process communication model
MULTICAST multicast via PGM, possibly encapsulated in UDP
TCP a network based transport
2.建立基础
由于在网络中两个端点是相对动态的，很难有一个稳定的单一连接点。
如果是这种情况，可以使用由0MQ提供的转发设备。
转发设备可以绑定2个不同端口，并且转发消息从一个端点到另一个端点。
这样做的话，在网络中转发设备能够变成一个稳定的点，其它组件都可以去连接。
0MQ提供了3种类型的设备
QUEUE, a forwarder for the request/response messaging pattern
FORWARDER, a forwarder for the publish/subscribe messaging pattern
STREAMER, a forwarder for the pipelined messaging pattern
3.选择通讯模式
0MQ支持4种模式
REQUEST/REPLY, bidirectional, load balanced and state based
PUBLISH/SUBSCRIBE, publish to multiple recipients at once
UPSTREAM / DOWNSTREAM, distribute data to nodes arranged in a pipeline
PAIR, communication exclusively between peers
Req/Rep
均衡负载请求：
server 1
Python代码
[*]import zmq
[*]context = zmq.Context()
[*]socket = context.socket(zmq.REP)
[*]socket.bind("tcp://127.0.0.1:5000")
[*]
[*]while True:
[*]msg = socket.recv()
[*]print "Got", msg
[*]socket.send(msg)
import zmq
context = zmq.Context()
socket = context.socket(zmq.REP)
socket.bind("tcp://127.0.0.1:5000")
while True:
msg = socket.recv()
print "Got", msg
socket.send(msg)
server 2
Python代码
[*]import zmq
[*]context = zmq.Context()
[*]socket = context.socket(zmq.REP)
[*]socket.bind("tcp://127.0.0.1:6000")
[*]
[*]while True:
[*]msg = socket.recv()
[*]print "Got", msg
[*]socket.send(msg)
import zmq
context = zmq.Context()
socket = context.socket(zmq.REP)
socket.bind("tcp://127.0.0.1:6000")
while True:
msg = socket.recv()
print "Got", msg
socket.send(msg)
client
Python代码
[*]import zmq
[*]context = zmq.Context()
[*]socket = context.socket(zmq.REQ)
[*]socket.connect("tcp://127.0.0.1:5000")
[*]socket.connect("tcp://127.0.0.1:6000")
[*]
[*]for i in range(10):
[*]msg = "msg %s" % i
[*]socket.send(msg)
[*]print "Sending", msg
[*]msg_in = socket.recv()
import zmq
context = zmq.Context()
socket = context.socket(zmq.REQ)
socket.connect("tcp://127.0.0.1:5000")
socket.connect("tcp://127.0.0.1:6000")
for i in range(10):
msg = "msg %s" % i
socket.send(msg)
print "Sending", msg
msg_in = socket.recv()
会发现client的请求会被均衡的分配给两个server
Example client output:
Sending msg 0
Sending msg 1
Sending msg 2
Sending msg 3
Sending msg 4
Sending msg 5
Sending msg 6
Sending msg 7
Sending msg 8
Sending msg 9
Example output server 1 at port 5000:
Got msg 0
Got msg 2
Got msg 4
Got msg 6
Got msg 8
Example output server 2 at port 6000:
Got msg 1
Got msg 3
Got msg 5
Got msg 7
Got msg 9
现在，如果我们要加入一个额外的server去管理我们的请求，我们将不得不修改我们的代码。
这是非常麻烦的，我们需要让每个client都知道有一个额外的server可以均衡请求。
为了解决这个问题，替代client直接去连接多个server的方式，client去连接转发设备，再由转发设备路由全部的消息给server。
Pub/Sub
在pub/sub模式下组件是松耦合的。类似于广播电台。
一个广播server为现场足球赛
Python代码
[*]import zmq
[*]from random import choice
[*]context = zmq.Context()
[*]socket = context.socket(zmq.PUB)
[*]socket.bind("tcp://127.0.0.1:5000")
[*]
[*]countries = ['netherlands','brazil','germany','portugal']
[*]events = ['yellow card', 'red card', 'goal', 'corner', 'foul']
[*]
[*]while True:
[*]msg = choice( countries ) +" "+ choice( events )
[*]print "->",msg
[*]socket.send( msg )
import zmq
from random import choice
context = zmq.Context()
socket = context.socket(zmq.PUB)
socket.bind("tcp://127.0.0.1:5000")
countries = ['netherlands','brazil','germany','portugal']
events = ['yellow card', 'red card', 'goal', 'corner', 'foul']
while True:
msg = choice( countries ) +" "+ choice( events )
print "->",msg
socket.send( msg )
输出
-> portugal corner
-> portugal yellow card
-> portugal goal
-> netherlands yellow card
-> germany yellow card
-> brazil yellow card
-> portugal goal
-> germany corner
…
一个客户端去收听特定的消息
Python代码
[*]import zmq
[*]
[*]context = zmq.Context()
[*]socket = context.socket(zmq.SUB)
[*]socket.connect("tcp://127.0.0.1:5000")
[*]socket.setsockopt(zmq.SUBSCRIBE, "netherlands")
[*]socket.setsockopt(zmq.SUBSCRIBE, "germany")
[*]
[*]while True:
[*]print socket.recv()
import zmq
context = zmq.Context()
socket = context.socket(zmq.SUB)
socket.connect("tcp://127.0.0.1:5000")
socket.setsockopt(zmq.SUBSCRIBE, "netherlands")
socket.setsockopt(zmq.SUBSCRIBE, "germany")
while True:
printsocket.recv()
输出
netherlands red card
netherlands goal
netherlands red card
germany foul
netherlands yellow card
germany foul
netherlands goal
netherlands corner
germany foul
netherlands corner
…
Pipelining
并发处理数据，其工作模式
一个工作者得到来自上游socket的消息，一旦处理完成后发送消息到下游。
Paired socket
服务器监听某个端口，客户端连接到这个端口，消息可以双向流动。
server
Python代码
[*]import zmq
[*]context = zmq.Context()
[*]socket = context.socket(zmq.PAIR)
[*]socket.bind("tcp://127.0.0.1:5555")
import zmq
context = zmq.Context()
socket = context.socket(zmq.PAIR)
socket.bind("tcp://127.0.0.1:5555")
client
Python代码
[*]import zmq
[*]context = zmq.Context()
[*]socket = context.socket(zmq.PAIR)
[*]socket.connect("tcp://127.0.0.1:5555")
import zmq
context = zmq.Context()
socket = context.socket(zmq.PAIR)
socket.connect("tcp://127.0.0.1:5555")
ps:
推荐
http://www.zeromq.org/
http://nichol.as/zeromq-an-introduction
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