zmq_recv(3) [debian man page]

ZMQ_RECV(3)							    0MQ Manual							       ZMQ_RECV(3)

NAME

       zmq_recv - receive a message from a socket

SYNOPSIS

       int zmq_recv (void *socket, zmq_msg_t *msg, int flags);

DESCRIPTION

       The zmq_recv() function shall receive a message 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 messages available on the specified
       socket the zmq_recv() function shall block until the request can be satisfied. The flags argument is a combination of the flags defined
       below:

       ZMQ_NOBLOCK
	   Specifies that the operation should be performed in non-blocking mode. If there are no messages available on the specified socket, the
	   zmq_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.

       An application wishing to determine if a message is composed of multiple parts does so by retrieving the value of the ZMQ_RCVMORE socket
       option on the socket it is receiving the message from. If there are no message parts to follow, or if the message is not composed of
       multiple parts, ZMQ_RCVMORE shall report a value of zero. Otherwise, ZMQ_RCVMORE shall report a value of 1, indicating that more message
       parts are to follow.

RETURN VALUE

       The zmq_recv() function shall return zero 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_recv() operation is not supported by this socket type.

       EFSM
	   The zmq_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_recv (socket, &msg, 0);
	   assert (rc == 0);
	   /* Release message */
	   zmq_msg_close (&msg);

       Receiving a multi-part message.

	   int64_t 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_recv (socket, &part, 0);
	       assert (rc == 0);
	       /* 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_send(3) zmq_getsockopt(3) zmq_socket(7) zmq(7)

AUTHORS

       This manual page was written by the 0MQ community.

0MQ 2.2.0							    04/04/2012							       ZMQ_RECV(3)

Check Out this Related Man Page

ZMQ_MSG_INIT_DATA(3)						    0MQ Manual						      ZMQ_MSG_INIT_DATA(3)

NAME

       zmq_msg_init_data - initialise 0MQ message from a supplied buffer

SYNOPSIS

       typedef void (zmq_free_fn) (void *data, void *hint);

       int zmq_msg_init_data (zmq_msg_t *msg, void *data, size_t size, zmq_free_fn *ffn, void *hint);

DESCRIPTION

       The zmq_msg_init_data() function shall initialise the message object referenced by msg to represent the content referenced by the buffer
       located at address data, size bytes long. No copy of data shall be performed and 0MQ shall take ownership of the supplied buffer.

       If provided, the deallocation function ffn shall be called once the data buffer is no longer required by 0MQ, with the data and hint
       arguments supplied to zmq_msg_init_data().

	   Caution
	   Never access zmq_msg_t members directly, instead always use the zmq_msg family of functions.

	   Caution
	   The deallocation function ffn needs to be thread-safe, since it will be called from an arbitrary thread.

	   Caution
	   The functions zmq_msg_init(), zmq_msg_init_data() and zmq_msg_init_size() are mutually exclusive. Never initialize the same zmq_msg_t
	   twice.

RETURN VALUE

       The zmq_msg_init_data() function shall return zero if successful. Otherwise it shall return -1 and set errno to one of the values defined
       below.

ERRORS

       No errors are defined.

EXAMPLE

       Initialising a message from a supplied buffer.

	   void my_free (void *data, void *hint)
	   {
	       free (data);
	   }

	       /*  ...	*/

	   void *data = malloc (6);
	   assert (data);
	   memcpy (data, "ABCDEF", 6);
	   zmq_msg_t msg;
	   rc = zmq_msg_init_data (&msg, data, 6, my_free, NULL);
	   assert (rc == 0);

SEE ALSO

       zmq_msg_init_size(3) zmq_msg_init(3) zmq_msg_close(3) zmq_msg_data(3) zmq_msg_size(3) zmq(7)

AUTHORS

       This manual page was written by the 0MQ community.

0MQ 2.2.0							    04/04/2012						      ZMQ_MSG_INIT_DATA(3)

Linux and UNIX Man Pages

zmq_recv(3) [debian man page]

Check Out this Related Man Page