Cfengine3 Messaging

> what would be killer is a combination of the latest cfengine
> (with promise theory) and 0mq.

http://lists.zeromq.org/pipermail/zeromq-dev/2011-February/009491.html

0mq

ZeroMQ comes with 5 basic patterns

• Synchronous Request/Response
• Asynchronous Request/Response
• Publish/Subscribe
• Push/Pull
• Exclusive Pair

Synchronous Request/Response

Client Requests

socket = context.socket(zmq.REQ)
socket.connect("tcp://wbhs-pkg.webhuis.nl:8080")

#  Do 10 requests, waiting each time for a response
print("Sending request %s ..." % request)
socket.send(b"Hello")

#  Get the reply.
message = socket.recv()
print("Received reply %s [ %s ]" % (request, message))

Server Replies

socket = context.socket(zmq.REP)
socket.bind("tcp://10.68.71.184:8080")

#  Wait for next request from client
message = socket.recv()
print("Received request: %s" % message)

#  Send reply back to client
socket.send(b"World")

Publish/Subscribe

Server publishes

ctx = zmq.Context()
publisher = ctx.socket(zmq.PUB)

publisher.bind("tcp://10.68.71.184:5556")

time.sleep(5)

sequence = 0
id = 0
data =1000

while sequence < 20:
  id += 1;
  data += 1000;
  publisher.send("%i %i %i" % (sequence, id, data));
  sequence += 1

Client subscriber receives

context = zmq.Context()
socket = context.socket(zmq.SUB)

print("Collecting updates from server...")
socket.connect("tcp://10.68.71.184:5556")

socket.setsockopt(zmq.SUBSCRIBE, b'')

for update_nbr in range(5):
    string = socket.recv_string()
    print string

Output

0 1 2000
1 2 3000
2 3 4000
3 4 5000
4 5 6000