zmq_msg_get(3)

zmq_msg_get(3)

ØMQ Manual - ØMQ/4.2.0

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 ØMQ 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); }

See also

zmq_msg_set(3) zmq_msg_init(3) zmq_msg_close(3) zmq(7)

Authors

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