#
# Freelance Client - Model 1
# Uses REQ socket to query one or more services
#
# Author: Daniel Lundin <dln(at)eintr(dot)org>
#
import sys
import time
import zmq
REQUEST_TIMEOUT = 1000 # ms
MAX_RETRIES = 3 # Before we abandon
def try_request(ctx, endpoint, request):
print "I: Trying echo service at %s…" % endpoint
client = ctx.socket(zmq.REQ)
client.setsockopt(zmq.LINGER, 0) # Terminate early
client.connect(endpoint)
client.send(request)
poll = zmq.Poller()
poll.register(client, zmq.POLLIN)
socks = dict(poll.poll(REQUEST_TIMEOUT))
if socks.get(client) == zmq.POLLIN:
reply = client.recv_multipart()
else:
reply = ''
poll.unregister(client)
client.close()
return reply
context = zmq.Context()
request = "Hello world"
reply = None
endpoints = len(sys.argv) - 1
if endpoints == 0:
print "I: syntax: %s <endpoint> …" % sys.argv[0]
elif endpoints == 1:
# For one endpoint, we retry N times
endpoint = sys.argv[1]
for retries in xrange(MAX_RETRIES):
reply = try_request(context, endpoint, request)
if reply:
break # Success
print "W: No response from %s, retrying" % endpoint
else:
# For multiple endpoints, try each at most once
for endpoint in sys.argv[1:]:
reply = try_request(context, endpoint, request)
if reply:
break # Success
print "W: No response from %s" % endpoint
if reply:
print "Service is running OK"