88 lines
3.1 KiB
Text
88 lines
3.1 KiB
Text
= nng_ctx_send(3)
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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_ctx_send - send message using context asynchronously
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== SYNOPSIS
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[source, c]
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----
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#include <nng/nng.h>
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void nng_ctx_send(nng_ctx ctx, nng_aio *aio);
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----
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== DESCRIPTION
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The `nng_ctx_send()` sends a xref:nng_msg.5.adoc[message] using the
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xref:nng_ctx.5.adoc[context] _ctx_ asynchronously.
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The message to send must have previously been set on the _aio_
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using the xref:nng_aio_set_msg.3.adoc[`nng_aio_set_msg()`] function.
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The function assumes ownership of the message.
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If the message was successfully queued for delivery to the socket,
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then the _aio_ will be completed, and xref:nng_aio_result.3.adoc[`nng_aio_result()`]
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will return zero.
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In this case the socket will dispose of the message when it is finished with it.
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NOTE: The operation will be completed, and the callback associated
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with the _aio_ executed, as soon as the socket accepts the message
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for sending.
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This does _not_ indicate that the message was actually delivered, as it
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may still be buffered in the sending socket, buffered in the receiving
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socket, or in flight over physical media.
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If the operation fails for any reason (including cancellation or timeout),
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then the _aio_ callback will be executed and
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xref:nng_aio_result.3.adoc[`nng_aio_result()`] will return a non-zero error status.
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In this case, the callback has a responsibility to retrieve the message from
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the _aio_ with xref:nng_aio_get_msg.3.adoc[`nng_aio_get_msg()`] and dispose of
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it appropriately.
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(This may include retrying the send operation on the same or a different
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socket, or deallocating the message with xref:nng_msg_free.3.adoc[`nng_msg_free()`].)
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NOTE: The semantics of what sending a message means varies from protocol to
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protocol, so examination of the protocol documentation is encouraged.
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TIP: Context send operations are asynchronous.
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If a synchronous operation is needed, one can be constructed by using a
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`NULL` callback on the _aio_ and then waiting for the operation using
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xref:nng_aio_wait.3.adoc[`nng_aio_wait()`].
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== RETURN VALUES
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None. (The operation completes asynchronously.)
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== ERRORS
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[horizontal]
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`NNG_ECANCELED`:: The operation was aborted.
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`NNG_ECLOSED`:: The context _ctx_ is not open.
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`NNG_EMSGSIZE`:: The message is too large.
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`NNG_ENOMEM`:: Insufficient memory is available.
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`NNG_ENOTSUP`:: The protocol for context _ctx_ does not support sending.
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`NNG_ESTATE`:: The context _ctx_ cannot send data in this state.
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`NNG_ETIMEDOUT`:: The send timeout expired.
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== SEE ALSO
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[.text-left]
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xref:nng_aio_get_msg.3.adoc[nng_aio_get_msg(3)],
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xref:nng_aio_set_msg.3.adoc[nng_aio_set_msg(3)],
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xref:nng_msg_alloc.3.adoc[nng_msg_alloc(3)],
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xref:nng_strerror.3.adoc[nng_strerror(3)],
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xref:nng_aio.5.adoc[nng_aio(5)],
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xref:nng_ctx.5.adoc[nng_ctx(5)],
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xref:nng_msg.5.adoc[nng_msg(5)],
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xref:nng.7.adoc[nng(7)]
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