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/nng.h>

void nng_ctx_send(nng_ctx ctx, nng_aio *aio);


The nng_ctx_send() sends a message using the context ctx asynchronously.

The message to send must have previously been set on the aio using the nng_aio_set_msg() function. The function assumes “ownership” of the message.

If the message was successfully queued for delivery to the socket, then the aio will be completed, and nng_aio_result() will return zero. In this case the socket will dispose of the message when it is finished with it.

The operation will be “completed”, and the callback associated with the aio executed, as soon as the socket accepts the message for sending. This does not indicate that the message was actually delivered, as it may still be buffered in the sending socket, buffered in the receiving socket, or in flight over physical media.

If the operation fails for any reason (including cancellation or timeout), then the aio callback will be executed and nng_aio_result() will return a non-zero error status. In this case, the callback has a responsibility to retrieve the message from the aio with nng_aio_get_msg() and dispose of it appropriately. (This may include retrying the send operation on the same or a different socket, or deallocating the message with nng_msg_free().)

The semantics of what sending a message means varies from protocol to protocol, so examination of the protocol documentation is encouraged.
Context send operations are asynchronous. If a synchronous operation is needed, one can be constructed by using a NULL callback on the aio and then waiting for the operation using nng_aio_wait().


None. (The operation completes asynchronously.)



The operation was aborted.


The context ctx is not open.


The message is too large.


Insufficient memory is available.


The protocol for context ctx does not support sending.


The context ctx cannot send data in this state.


The send timeout expired.