Zproxy (3) Linux Manual Page

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: m[blue]m[]

Report bugs to the email <m[blue]zeromq-dev [at] lists.zeromq.orgm[][1]>

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 0MQ: 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.

Notes

1.

zeromq-dev [at] lists.zeromq.org

mailto:zeromq-dev [at] lists.zeromq.org

zproxy (3) Linux Manual Page