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ZMQ_MSG_RECV(3)			  0MQ Manual		       ZMQ_MSG_RECV(3)

NAME
       zmq_msg_recv - receive a	message	part from a socket

SYNOPSIS
       int zmq_msg_recv	(zmq_msg_t *msg, void *socket, int flags);

DESCRIPTION
       The zmq_msg_recv() function is identical	to zmq_recvmsg(3), which shall
       be deprecated in	future versions. zmq_msg_recv()	is more	consistent
       with other message manipulation functions.

       The zmq_msg_recv() function shall receive a message part	from the
       socket referenced by the	socket argument	and store it in	the message
       referenced by the msg argument. Any content previously stored in	msg
       shall be	properly deallocated. If there are no message parts available
       on the specified	socket the zmq_msg_recv() function shall block until
       the request can be satisfied. The flags argument	is a combination of
       the flags defined below:

       ZMQ_DONTWAIT
	   Specifies that the operation	should be performed in non-blocking
	   mode. If there are no messages available on the specified socket,
	   the zmq_msg_recv() function shall fail with errno set to EAGAIN.

   Multi-part messages
       A 0MQ message is	composed of 1 or more message parts. Each message part
       is an independent zmq_msg_t in its own right. 0MQ 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 processes multi-part	messages must use the
       ZMQ_RCVMORE zmq_getsockopt(3) option after calling zmq_msg_recv() to
       determine if there are further parts to receive.

RETURN VALUE
       The zmq_msg_recv() 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 no messages are available at
	   the moment.

       ENOTSUP
	   The zmq_msg_recv() operation	is not supported by this socket	type.

       EFSM
	   The zmq_msg_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 ZMQ_REP. See	the messaging patterns section of
	   zmq_socket(3) for more information.

       ETERM
	   The 0MQ 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.

       EFAULT
	   The message passed to the function was invalid.

EXAMPLE
       Receiving a message from	a socket.

	   /* Create an	empty 0MQ message */
	   zmq_msg_t msg;
	   int rc = zmq_msg_init (&msg);
	   assert (rc == 0);
	   /* Block until a message is available to be received	from socket */
	   rc =	zmq_msg_recv (&msg, socket, 0);
	   assert (rc != -1);
	   /* Release message */
	   zmq_msg_close (&msg);

       Receiving a multi-part message.

	   int more;
	   size_t more_size = sizeof (more);
	   do {
	       /* Create an empty 0MQ message to hold the message part */
	       zmq_msg_t part;
	       int rc =	zmq_msg_init (&part);
	       assert (rc == 0);
	       /* Block	until a	message	is available to	be received from socket	*/
	       rc = zmq_msg_recv (&part, socket, 0);
	       assert (rc != -1);
	       /* Determine if more message parts are to follow	*/
	       rc = zmq_getsockopt (socket, ZMQ_RCVMORE, &more,	&more_size);
	       assert (rc == 0);
	       zmq_msg_close (&part);
	   } while (more);

SEE ALSO
       zmq_recv(3) zmq_send(3) zmq_msg_send(3) zmq_getsockopt(3) zmq_socket(7)
       zmq(7)

AUTHORS
       This page was written by	the 0MQ	community. To make a change please
       read the	0MQ Contribution Policy	at
       http://www.zeromq.org/docs:contributing.

0MQ 4.3.1			  01/12/2019		       ZMQ_MSG_RECV(3)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLE | SEE ALSO | AUTHORS

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