DragonFly On-Line Manual Pages

XS_SEND(3)                   Crossroads I/O Manual                  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. Crossroads
       ensures 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 message 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
           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
       Applications that wish to use zero-copy messaging must use
       xs_sendmsg(3) instead of xs_send().

       xs_recv(3) xs_socket(7) xs(7)

AUTHORS
       This man page was written by Martin Sustrik <sustrik@250bpm.com[1]>,
       Martin Lucina <martin@lucina.net[2]> and Pieter Hintjens
       <ph@imatix.com[3]>.

NOTES
        1. sustrik@250bpm.com
           mailto:sustrik@250bpm.com

        2. martin@lucina.net
           mailto:martin@lucina.net

        3. ph@imatix.com
           mailto:ph@imatix.com

Crossroads I/O 1.2.0              02/17/2016                        XS_SEND(3)