zproxy(3)

CZMQ Manual - CZMQ/3.0.1

Name

zproxy - run a steerable proxy in the background

Synopsis

//  Create new zproxy actor instance. The proxy switches messages between
//  a frontend socket and a backend socket; use the FRONTEND and BACKEND
//  commands to configure these:
//
//      zactor_t *proxy = zactor_new (zproxy, NULL);
//
//  Destroy zproxy instance. This destroys the two sockets and stops any
//  message flow between them:
//
//      zactor_destroy (&proxy);
//
//  Note that all zproxy commands are synchronous, so your application always
//  waits for a signal from the actor after each command.
//
//  Enable verbose logging of commands and activity:
//
//      zstr_send (proxy, "VERBOSE");
//      zsock_wait (proxy);
//
//  Specify frontend socket type -- see zsock_type_str () -- and attach to
//  endpoints, see zsock_attach (). Note that a proxy socket is always
//  serverish:
//
//      zstr_sendx (proxy, "FRONTEND", "XSUB", endpoints, NULL);
//      zsock_wait (proxy);
//
//  Specify backend socket type -- see zsock_type_str () -- and attach to
//  endpoints, see zsock_attach (). Note that a proxy socket is always
//  serverish:
//
//      zstr_sendx (proxy, "BACKEND", "XPUB", endpoints, NULL);
//      zsock_wait (proxy);
//
//  Capture all proxied messages; these are delivered to the application
//  via an inproc PULL socket that you have already bound to the specified
//  endpoint:
//
//      zstr_sendx (proxy, "CAPTURE", endpoint, NULL);
//      zsock_wait (proxy);
//
//  Pause the proxy. A paused proxy will cease processing messages, causing
//  them to be queued up and potentially hit the high-water mark on the
//  frontend or backend socket, causing messages to be dropped, or writing
//  applications to block:
//
//      zstr_sendx (proxy, "PAUSE", NULL);
//      zsock_wait (proxy);
//
//  Resume the proxy. Note that the proxy starts automatically as soon as it
//  has a properly attached frontend and backend socket:
//
//      zstr_sendx (proxy, "RESUME", NULL);
//      zsock_wait (proxy);
//
//  This is the zproxy constructor as a zactor_fn; the argument is a
//  character string specifying frontend and backend socket types as two
//  uppercase strings separated by a hyphen:
CZMQ_EXPORT void
    zproxy (zsock_t *pipe, void *unused);

//  Selftest
CZMQ_EXPORT void
    zproxy_test (bool verbose);

Description

A zproxy actor switches messages between a frontend and a backend socket. It acts much like the zmq_proxy_steerable method, though it makes benefit of CZMQ's facilities, to be somewhat simpler to set-up.

This class replaces zproxy_v2, and is meant for applications that use the CZMQ v3 API (meaning, zsock).

Example

From zproxy_test method

// Create and configure our proxy
zactor_t *proxy = zactor_new (zproxy, NULL);
assert (proxy);
if (verbose) {
 zstr_sendx (proxy, "VERBOSE", NULL);
 zsock_wait (proxy);
}
zstr_sendx (proxy, "FRONTEND", "PULL", "inproc://frontend", NULL);
zsock_wait (proxy);
zstr_sendx (proxy, "BACKEND", "PUSH", "inproc://backend", NULL);
zsock_wait (proxy);

// Connect application sockets to proxy
zsock_t *faucet = zsock_new_push (">inproc://frontend");
assert (faucet);
zsock_t *sink = zsock_new_pull (">inproc://backend");
assert (sink);

// Send some messages and check they arrived
char *hello, *world;
zstr_sendx (faucet, "Hello", "World", NULL);
zstr_recvx (sink, &hello, &world, NULL);
assert (streq (hello, "Hello"));
assert (streq (world, "World"));
zstr_free (&hello);
zstr_free (&world);

// Test pause/resume functionality
zstr_sendx (proxy, "PAUSE", NULL);
zsock_wait (proxy);
zstr_sendx (faucet, "Hello", "World", NULL);
zsock_set_rcvtimeo (sink, 100);
zstr_recvx (sink, &hello, &world, NULL);
assert (!hello && !world);

zstr_sendx (proxy, "RESUME", NULL);
zsock_wait (proxy);
zstr_recvx (sink, &hello, &world, NULL);
assert (streq (hello, "Hello"));
assert (streq (world, "World"));
zstr_free (&hello);
zstr_free (&world);

// Test capture functionality
zsock_t *capture = zsock_new_pull ("inproc://capture");
assert (capture);

// Switch on capturing, check that it works
zstr_sendx (proxy, "CAPTURE", "inproc://capture", NULL);
zsock_wait (proxy);
zstr_sendx (faucet, "Hello", "World", NULL);
zstr_recvx (sink, &hello, &world, NULL);
assert (streq (hello, "Hello"));
assert (streq (world, "World"));
zstr_free (&hello);
zstr_free (&world);

zstr_recvx (capture, &hello, &world, NULL);
assert (streq (hello, "Hello"));
assert (streq (world, "World"));
zstr_free (&hello);
zstr_free (&world);

zsock_destroy (&faucet);
zsock_destroy (&sink);
zsock_destroy (&capture); zactor_destroy (&proxy);

Authors

The czmq manual was written by the authors in the AUTHORS file.

Resources

Main web site:

Report bugs to the email <gro.qmorez.stsil|ved-qmorez#gro.qmorez.stsil|ved-qmorez>

Copyright

Copyright (c) 1991-2012 iMatix Corporation — http://www.imatix.com Copyright other contributors as noted in the AUTHORS file. This file is part of CZMQ, the high-level C binding for ØMQ: http://czmq.zeromq.org This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/. LICENSE included with the czmq distribution.

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