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ZMQ_MSG_GET

Section: 0MQ Manual (3)
Updated: 12/31/2016
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NAME

zmq_msg_get - get message property

SYNOPSIS

int zmq_msg_get (zmq_msg_t *message, int property);

DESCRIPTION

The zmq_msg_get() function shall return the value for the property specified by the property argument for the message pointed to by the message argument.

The following properties can be retrieved with the zmq_msg_get() function:

ZMQ_MORE

: Indicates that there are more message frames to follow after the message.

ZMQ_SRCFD

: Returns the file descriptor of the socket the message was read from. This allows application to retrieve the remote endpoint via getpeername(2). Be aware that the respective socket might be closed already, reused even. Currently only implemented for TCP sockets.

ZMQ_SHARED

: Indicates that a message MAY share underlying storage with another copy of this message.

RETURN VALUE

The zmq_msg_get() function shall return the value for the property if successful. Otherwise it shall return -1 and set errno to one of the values defined below.

ERRORS

EINVAL

: The requested property is unknown.

EXAMPLE

Receiving a multi-frame message.

zmq_msg_t frame;
while (true) {
    //  Create an empty 0MQ message to hold the message frame
    int rc = zmq_msg_init (&frame);
    assert (rc == 0);
    //  Block until a message is available to be received from socket
    rc = zmq_msg_recv (socket, &frame, 0);
    assert (rc != -1);
    if (zmq_msg_get (&frame, ZMQ_MORE))
        fprintf (stderr, "more\n");
    else {
        fprintf (stderr, "end\n");
        break;
    }
    zmq_msg_close (&frame);
}

AUTHORS

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