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authorMartin Sustrik <sustrik@250bpm.com>2012-02-16 10:01:47 +0900
committerMartin Sustrik <sustrik@250bpm.com>2012-02-16 10:01:47 +0900
commit4a7aad06d95701cf232198093ce396dcdbb53e5b (patch)
tree8ced8929e603a179d9434099244dfd782e705d5e /doc/xs_recv.txt
parent1fc63e4dbcf1438eb571d720f57be68852f820f7 (diff)
ZeroMQ renamed to Crossroads
Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
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+xs_recv(3)
+==========
+
+
+NAME
+----
+xs_recv - receive a message part from a socket
+
+
+SYNOPSIS
+--------
+*int xs_recv (void '*socket', void '*buf', size_t 'len', int 'flags');*
+
+
+DESCRIPTION
+-----------
+The _xs_recv()_ function shall receive a message from the socket referenced
+by the 'socket' argument and store it in the buffer referenced by the 'buf'
+argument. Any bytes exceeding the length specified by the 'len' argument shall
+be truncated. If there are no messages available on the specified 'socket'
+the _xs_recv()_ function shall block until the request can be satisfied.
+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 there
+are no messages available on the specified 'socket', the _xs_recv()_
+function shall fail with 'errno' set to EAGAIN.
+
+
+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 processes multipart messages must use the _XS_RCVMORE_
+linkxs:xs_getsockopt[3] option after calling _xs_recv()_ to determine if
+there are further parts to receive.
+
+RETURN VALUE
+------------
+The _xs_recv()_ function shall return number of bytes in the message
+if successful. Note that the value can exceed the value of the 'len' parameter
+in case the message was truncated. If not successful the function shall return
+`-1` and set 'errno' to one of the values defined below.
+
+
+ERRORS
+------
+*EAGAIN*::
+Non-blocking mode was requested and no messages are available at the moment.
+*ENOTSUP*::
+The _xs_recv()_ operation is not supported by this socket type.
+*EFSM*::
+The _xs_recv()_ 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 a message was
+available.
+
+
+EXAMPLE
+-------
+.Receiving a message from a socket
+----
+char buf [256];
+nbytes = xs_recv (socket, buf, 256, 0);
+assert (nbytes != -1);
+----
+
+
+SEE ALSO
+--------
+linkxs:xs_recvmsg[3]
+linkxs:xs_send[3]
+linkxs:xs_sendmsg[3]
+linkxs:xs_getsockopt[3]
+linkxs:xs_socket[7]
+linkxs:xs[7]
+
+
+AUTHORS
+-------
++This man page was written by Martin Sustrik <sustrik@250bpm.com>, Martin
++Lucina <martin@lucina.net> and Pieter Hintjens <ph@imatix.com>.
+