mirror of
https://github.com/zeromq/libzmq.git
synced 2024-12-25 22:30:51 +08:00
91 lines
3.1 KiB
Plaintext
91 lines
3.1 KiB
Plaintext
= zmq_proxy(3)
|
|
|
|
== NAME
|
|
zmq_proxy - start built-in 0MQ proxy
|
|
|
|
|
|
== SYNOPSIS
|
|
*int zmq_proxy (void '*frontend', void '*backend', void '*capture');*
|
|
|
|
|
|
== DESCRIPTION
|
|
The _zmq_proxy()_ function starts the built-in 0MQ proxy in the current
|
|
application thread.
|
|
|
|
The proxy connects a frontend socket to a backend socket. Conceptually, data
|
|
flows from frontend to backend. Depending on the socket types, replies may flow
|
|
in the opposite direction. The direction is conceptual only; the proxy is fully
|
|
symmetric and there is no technical difference between frontend and backend.
|
|
|
|
Before calling _zmq_proxy()_ you must set any socket options, and connect or
|
|
bind both frontend and backend sockets. The two conventional proxy models are:
|
|
|
|
_zmq_proxy()_ runs in the current thread and returns only if/when the current
|
|
context is closed.
|
|
|
|
If the capture socket is not NULL, the proxy shall send all messages, received
|
|
on both frontend and backend, to the capture socket. The capture socket should
|
|
be a 'ZMQ_PUB', 'ZMQ_DEALER', 'ZMQ_PUSH', or 'ZMQ_PAIR' socket.
|
|
|
|
Refer to xref:zmq_socket.adoc[zmq_socket] for a description of the available socket types.
|
|
|
|
== EXAMPLE USAGE
|
|
|
|
Shared Queue
|
|
~~~~~~~~~~~~
|
|
|
|
When the frontend is a ZMQ_ROUTER socket, and the backend is a ZMQ_DEALER
|
|
socket, the proxy shall act as a shared queue that collects requests from a
|
|
set of clients, and distributes these fairly among a set of services.
|
|
Requests shall be fair-queued from frontend connections and distributed evenly
|
|
across backend connections. Replies shall automatically return to the client
|
|
that made the original request.
|
|
|
|
Forwarder
|
|
~~~~~~~~~
|
|
|
|
When the frontend is a ZMQ_XSUB socket, and the backend is a ZMQ_XPUB socket,
|
|
the proxy shall act as a message forwarder that collects messages from a set
|
|
of publishers and forwards these to a set of subscribers. This may be used to
|
|
bridge networks transports, e.g. read on tcp:// and forward on pgm://.
|
|
|
|
Streamer
|
|
~~~~~~~~
|
|
|
|
When the frontend is a ZMQ_PULL socket, and the backend is a ZMQ_PUSH socket,
|
|
the proxy shall collect tasks from a set of clients and forwards these to a set
|
|
of workers using the pipeline pattern.
|
|
|
|
== RETURN VALUE
|
|
The _zmq_proxy()_ function always returns `-1` and 'errno' set to *ETERM* or
|
|
*EINTR* (the 0MQ 'context' associated with either of the specified sockets was
|
|
terminated) or *EFAULT* (the provided 'frontend' or 'backend' was invalid).
|
|
|
|
|
|
== EXAMPLE
|
|
.Creating a shared queue proxy
|
|
----
|
|
// Create frontend and backend sockets
|
|
void *frontend = zmq_socket (context, ZMQ_ROUTER);
|
|
assert (frontend);
|
|
void *backend = zmq_socket (context, ZMQ_DEALER);
|
|
assert (backend);
|
|
// Bind both sockets to TCP ports
|
|
assert (zmq_bind (frontend, "tcp://*:5555") == 0);
|
|
assert (zmq_bind (backend, "tcp://*:5556") == 0);
|
|
// Start the queue proxy, which runs until ETERM
|
|
zmq_proxy (frontend, backend, NULL);
|
|
----
|
|
|
|
|
|
== SEE ALSO
|
|
* xref:zmq_bind.adoc[zmq_bind]
|
|
* xref:zmq_connect.adoc[zmq_connect]
|
|
* xref:zmq_socket.adoc[zmq_socket]
|
|
* xref:zmq.adoc[zmq]
|
|
|
|
|
|
== AUTHORS
|
|
This page was written by the 0MQ community. To make a change please
|
|
read the 0MQ Contribution Policy at <https://zeromq.org/how-to-contribute/>.
|