This documentation is for version v1.3.0 of NNG, but the latest released version is v1.8.0. see the documentation for v1.8.0 for the most up-to-date information.


#include <nng/protocol/pipeline0/push.h>


The push protocol is one half of a pipeline pattern. The other side is the pull protocol.

In the pipeline pattern, pushers distribute messages to pullers. Each message sent by a pusher will be sent to one of its peer pullers, chosen in a round-robin fashion from the set of connected peers available for receiving. This property makes this pattern useful in load-balancing scenarios.

Socket Operations

The nng_push0_open() call creates a pusher socket. This socket may be used to send messages, but is unable to receive them. Attempts to receive messages will result in NNG_ENOTSUP.

Send operations will observe flow control (back-pressure), so that only peers capable of accepting a message will be considered. If no peer is available to receive a message, then the send operation will wait until one is available, or the operation times out.

Although the pipeline protocol honors flow control, and attempts to avoid dropping messages, no guarantee of delivery is made. Furthermore, as there is no capability for message acknowledgment, applications that need reliable delivery are encouraged to consider the req protocol instead.

Protocol Versions

Only version 0 of this protocol is supported. (At the time of writing, no other versions of this protocol have been defined.)

Protocol Options

The push protocol has no protocol-specific options.

Protocol Headers

The push protocol has no protocol-specific headers.