Editing Cfengine3 Messaging (section)

== Information processing Nodes ==
Information processing Nodes receive their information through message feeds and for their part may be willing to share their information through views. Data would be an information processing Node, relying on a defined set of feeds, an information processing process that builds the Universal Truth and defined autorized views that share the information stored.
=== cf-messaged ===
In this proof of concept the listener simply adds every message to a file, queue.txt as were it a queue. Nodes in fect feed the listener with information and the listener knows how to process incoming messages. Feeds are input schemas. The example uses the typical Zeromq port 5555, but why would we not use a more typical CFEngine port 5309?
<pre>
import time
import zmq

context = zmq.Context()
socket = context.socket(zmq.REP)
socket.bind("tcp://10.68.71.184:5555")

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

    #  Do some 'work'
    time.sleep(1)

    with open("queue.txt", "a") as queue:
      queue.write(message + "\n")

    #  Send reply back to client
    socket.send( response )

</pre>
The output would be:
<pre>
root@wbhs-pkg:~# tail -F queue.txt 
{host:{uqhost:x2gvdt0001,domain:webhuis.nl,role:x2gvdt}}
{host:{uqhost:kvmutl0004,domain:webhuis.nl,role:kvmutl}}
{host:{uqhost:x2gvdt0001,domain:webhuis.nl,role:x2gvdt}}
{host:{uqhost:x2gvdt0001,domain:webhuis.nl,role:x2gvdt}}
</pre>
When a message is received the daemon places the message in a local queue for processing. The sending node receives a hard coded response "message received", but this could be any response as a result on the side of the listener. The response is useful when it triggers the node to supply more information in more messages.