NNG_SEND_AIO(3)

NAME
nng_send_aio - send message asynchronously

SYNOPSIS

    #include <nng/nng.h>
    void nng_send_aio(nng_socket s, nng_aio *aio);

DESCRIPTION

The nng_send_aio() sends a message using the socket s 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.

    Note

    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().)

    Note

    The semantics of what sending a message means varies from protocol to protocol, so examination of the protocol documentation is encouraged. (For example, with a pub socket the data is broadcast, so that any peers who have a suitable subscription will be able to receive it using nng_recv() or a similar function.) Furthermore, some protocols may not support sending (such as sub) or may require other conditions. (For example, rep sockets cannot normally send data, which are responses to requests, until they have first received a request.)

RETURN VALUES

None. (The operation completes asynchronously.)

ERRORS

NNG_ECANCELED
    The operation was aborted.

NNG_ECLOSED
    The socket s is not open.

NNG_EMSGSIZE
    The message is too large.

NNG_ENOMEM
    Insufficient memory is available.

NNG_ENOTSUP
    The protocol for socket s does not support sending.

NNG_ESTATE
    The socket s cannot send data in this state.

NNG_ETIMEDOUT
    The send timeout expired.

SEE ALSO

nng_aio_get_msg(3), nng_aio_set_msg(3), nng_msg_alloc(3), nng_strerror(3), nng_aio(5), nng_msg(5), nng_socket(5), nng(7)