This documentation is for the TIP (development tree) of NNG and may represent unreleased changes or functionality that is experimental, and is subject to change before release. The latest released version is v1.8.0. See the documentation for v1.8.0 for the most up-to-date information.

nng_ctx_sendmsg(3)

NAME

nng_ctx_sendmsg - send message using context

SYNOPSIS

#include <nng/nng.h>

int nng_ctx_sendmsg(nng_ctx c, nng_msg *msg, int flags);

DESCRIPTION

The nng_ctx_sendmsg() sends message msg using the context ctx.

If the function returns zero, indicating it has accepted the message for delivery, then the msg is owned by the socket s, and the caller must not make any further use of it. The socket will free the message when it is finished.

If the function returns non-zero, then it is the caller’s responsibility to dispose of the msg, which may include freeing it, sending it to another socket, or simply trying again later.

The semantics of what sending a message means vary from protocol to protocol, so examination of the protocol documentation is encouraged.

The flags may contain the following value:

NNG_FLAG_NONBLOCK: The function returns immediately, regardless of whether the context is able to accept the data or not. If the context is unable to accept the data (such as if backpressure exists because the peers are consuming messages too slowly, or no peer is present), then the function will return with NNG_EAGAIN. If this flag is not specified, then the function will block if such a condition exists.

Regardless of the presence or absence of NNG_FLAG_NONBLOCK, there may be queues between the sender and the receiver. Furthermore, there is no guarantee that the message has actually been delivered. Finally, with some protocols, the semantic is implicitly NNG_FLAG_NONBLOCK.

RETURN VALUES

This function returns 0 on success, and non-zero otherwise.

ERRORS

`NNG_EAGAIN`	The operation would block, but `NNG_FLAG_NONBLOCK` was specified.
`NNG_ECLOSED`	The context or socket is not open.
`NNG_EINVAL`	An invalid set of flags was specified.
`NNG_EMSGSIZE`	The value of size is too large.
`NNG_ENOMEM`	Insufficient memory is available.
`NNG_ENOTSUP`	The protocol does not support sending.
`NNG_ESTATE`	The context cannot send data in this state.
`NNG_ETIMEDOUT`	The operation timed out.