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+## Push Protocol (_PUSH_)
+
+The ((_PUSH_ protocol))(((protocol, _PUSH_)))  is one half of a ((pipeline pattern)).
+The other side is the xref:pull.adoc[_PULL_] protocol.
+
+In the pipeline pattern, pushers distribute messages to pullers.
+Each message sent by a pusher will be sent to one of its ready peer pullers, chosen in a round-robin fashion.
+This property makes this pattern useful in ((load-balancing)) scenarios.
+
+#### Socket Operations
+
+The xref:nng_push_open.adoc[`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.
+
+NOTE: 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 xref:nng_req.adoc[_REQ_] protocol instead.
+
+#### Protocol Versions
+
+Only version 0 of this protocol is supported.footnote:[At the time of writing, no other versions of this protocol have been defined.]
+
+#### Protocol Options
+
+xref:nng_options.adoc#NNG_OPT_SENDBUF[`NNG_OPT_SENDBUF`]::
+
+    (`int`, 0 - 8192)
+    Normally this is set to zero, indicating that send operations are unbuffered.
+    In unbuffered operation, send operations will wait until a suitable peer is available to receive the message.
+    If this is set to a positive value (up to 8192), then an intermediate buffer is provided for the socket with the specified depth (in messages).
+
+NOTE: Transport layer buffering may occur in addition to any socket buffer determined by this option.
+
+#### Protocol Headers
+
+The _PUSH_ protocol has no protocol-specific headers.