zproxy(3)
=========

NAME
----
zproxy - run a steerable proxy in the background

SYNOPSIS
--------
----

//  Constructor
//  Create a new zproxy object. You must create the frontend and backend
//  sockets, configure them, and connect or bind them, before you pass them
//  to the constructor. Do NOT use the sockets again, after passing them to
//  this method.
CZMQ_EXPORT zproxy_t *
    zproxy_new (zctx_t *ctx, void *frontend, void *backend);

//  Destructor
//  Destroy a zproxy object; note this first stops the proxy.
CZMQ_EXPORT void
    zproxy_destroy (zproxy_t **self_p);

//  Copy all proxied messages to specified endpoint; if this is NULL, any
//  in-progress capturing will be stopped. You must already have bound the
//  endpoint to a PULL socket.
CZMQ_EXPORT void
    zproxy_capture (zproxy_t *self, const char *endpoint);

//  Pauses a zproxy object; a paused proxy will cease processing messages,
//  causing them to be queued up and potentially hit the high-water mark on
//  the frontend socket, causing messages to be dropped, or writing
//  applications to block.
CZMQ_EXPORT void
    zproxy_pause (zproxy_t *self);

//  Resume a zproxy object
CZMQ_EXPORT void
    zproxy_resume (zproxy_t *self);

// Self test of this class
CZMQ_EXPORT void
    zproxy_test (bool verbose);
----

DESCRIPTION
-----------

The zproxy class provides an equivalent to the ZMQ steerable proxy, on
all versions of ZeroMQ.


EXAMPLE
-------
.From zproxy_test method
----
    zctx_t *ctx = zctx_new ();
    void *frontend = zsocket_new (ctx, ZMQ_PULL);
    int rc = zsocket_bind (frontend, "inproc://frontend");
    assert (rc == 0);
    void *backend = zsocket_new (ctx, ZMQ_PUSH);
    rc = zsocket_bind (backend, "inproc://backend");
    assert (rc == 0);
    zproxy_t *proxy = zproxy_new (ctx, frontend, backend);

    //  Connect application sockets to proxy
    void *faucet = zsocket_new (ctx, ZMQ_PUSH);
    rc = zsocket_connect (faucet, "inproc://frontend");
    assert (rc == 0);
    void *sink = zsocket_new (ctx, ZMQ_PULL);
    rc = zsocket_connect (sink, "inproc://backend");
    assert (rc == 0);

    //  Send some messages and check they arrived
    zstr_send (faucet, "Hello");
    char *string = zstr_recv (sink);
    assert (streq (string, "Hello"));
    zstr_free (&string);
    
    //  Check pause/resume functionality
    zproxy_pause (proxy);
    zstr_send (faucet, "World");

    zproxy_resume (proxy);
    string = zstr_recv (sink);
    assert (streq (string, "World"));
    zstr_free (&string);
    
    //  Create capture socket, must be a PULL socket
    void *capture = zsocket_new (ctx, ZMQ_PULL);
    rc = zsocket_bind (capture, "inproc://capture");
    assert (rc == 0);

    //  Switch on capturing, check that it works
    zproxy_capture (proxy, "inproc://capture");
    zstr_send (faucet, "Hello");
    
    string = zstr_recv (sink);
    assert (streq (string, "Hello"));
    zstr_free (&string);
    
    string = zstr_recv (capture);
    assert (streq (string, "Hello"));
    zstr_free (&string);
    zproxy_destroy (&proxy);
    zctx_destroy (&ctx);

----

SEE ALSO
--------
linkczmq:czmq[7]
