xs_send(3) ========== NAME ---- xs_send - send a message part on a socket SYNOPSIS -------- *int xs_send (void '*socket', void '*buf', size_t 'len', int 'flags');* DESCRIPTION ----------- The _xs_send()_ function shall queue a message created from the buffer referenced by the 'buf' and 'len' arguments. The 'flags' argument is a combination of the flags defined below: *XS_DONTWAIT*:: Specifies that the operation should be performed in non-blocking mode. If the message cannot be queued on the 'socket', the _xs_send()_ function shall fail with 'errno' set to EAGAIN. *XS_SNDMORE*:: Specifies that the message being sent is a multi-part message, and that further message parts are to follow. Refer to the section regarding multi-part messages below for a detailed description. NOTE: A successful invocation of _xs_send()_ does not indicate that the message has been transmitted to the network, only that it has been queued on the 'socket' and Crossroads have assumed responsibility for the message. Multi-part messages ~~~~~~~~~~~~~~~~~~~ A Crossroads message is composed of 1 or more message parts. Each message part is an independent 'xs_msg_t' in its own right. Crossroads ensure atomic delivery of messages; peers shall receive either all _message parts_ of a message or none at all. The total number of message parts is unlimited except by available memory. An application that sends multipart messages must use the _XS_SNDMORE_ flag when sending each data part except the final one. RETURN VALUE ------------ The _xs_send()_ function shall return number of bytes in the message if successful. Otherwise it shall return `-1` and set 'errno' to one of the values defined below. ERRORS ------ *EAGAIN*:: Non-blocking mode was requested and the message cannot be sent at the moment. *ENOTSUP*:: The _xs_send()_ operation is not supported by this socket type. *EFSM*:: The _xs_send()_ operation cannot be performed on this socket at the moment due to the socket not being in the appropriate state. This error may occur with socket types that switch between several states, such as XS_REP. See the _messaging patterns_ section of linkxs:xs_socket[3] for more information. *ETERM*:: The 'context' associated with the specified 'socket' was terminated. *ENOTSOCK*:: The provided 'socket' was invalid. *EINTR*:: The operation was interrupted by delivery of a signal before the message was sent. EXAMPLE ------- .Sending a multi-part message ---- /* Send a multi-part message consisting of three parts to socket */ rc = xs_send (socket, "ABC", 3, XS_SNDMORE); assert (rc == 3); rc = xs_send (socket, "DEFGH", 5, XS_SNDMORE); assert (rc == 5); /* Final part; no more parts to follow */ rc = xs_send (socket, "JK", 2, 0); assert (rc == 2); ---- SEE ALSO -------- linkxs:xs_sendmsg[3] linkxs:xs_recv[3] linkxs:xs_recvmsg[3] linkxs:xs_socket[7] linkxs:xs[7] AUTHORS ------- +This man page was written by Martin Sustrik , Martin +Lucina and Pieter Hintjens .