= nng_pull(7)
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//
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// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
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// Copyright 2018 Capitar IT Group BV <info@capitar.com>
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//
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// This document is supplied under the terms of the MIT License, a
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// copy of which should be located in the distribution where this
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// file was obtained (LICENSE.txt). A copy of the license may also be
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// found online at https://opensource.org/licenses/MIT.
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//
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== NAME
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nng_pull - pull protocol
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== SYNOPSIS
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[source,c]
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----
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#include <nng/protocol/pipeline0/pull.h>
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----
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== DESCRIPTION
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(((protocol, _pull_)))
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The ((_pull_ protocol)) is one half of a ((pipeline pattern)).
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The other half is the xref:nng_push.7.adoc[_push_] protocol.
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In the pipeline pattern, pushers distribute messages to pullers.
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Each message sent
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by a pusher will be sent to one of its peer pullers,
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chosen in a round-robin fashion
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from the set of connected peers available for receiving.
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This property makes this pattern useful in ((load-balancing)) scenarios.
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=== Socket Operations
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The xref:nng_pull_open.3.adoc[`nng_pull0_open()`] functions create a puller socket.
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This socket may be used to receive messages, but is unable to send them.
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Attempts to send messages will result in `NNG_ENOTSUP`.
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When receiving messages, the _pull_ protocol accepts messages as
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they arrive from peers.
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If two peers both have a message ready, the
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order in which messages are handled is undefined.
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=== Protocol Versions
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Only version 0 of this protocol is supported.
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(At the time of writing, no other versions of this protocol have been defined.)
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=== Protocol Options
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The _pull_ protocol has no protocol-specific options.
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=== Protocol Headers
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The _pull_ protocol has no protocol-specific headers.
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== SEE ALSO
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[.text-left]
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xref:nng_pull_open.3.adoc[nng_pull_open(3)],
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xref:nng_push.7.adoc[nng_push(7)],
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xref:nng.7.adoc[nng(7)],
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