NAME

       zmq_msg_gets - get message metadata property

SYNOPSIS

       const char *zmq_msg_gets (zmq_msg_t *message, const char *property);

DESCRIPTION

       The zmq_msg_gets() function shall return the string value for the metadata property specified by the
       property argument for the message pointed to by the message argument. Both the property argument and the
       value shall be NULL-terminated UTF8-encoded strings.

       Metadata is defined on a per-connection basis during the ZeroMQ connection handshake as specified in
       <rfc.zeromq.org/spec:37>.

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

           Socket-Type
           Identity
           Resource

       Additionally, when available for the underlying transport, the Peer-Address property will return the IP
       address of the remote endpoint as returned by getnameinfo(2).

       Other properties may be defined based on the underlying security mechanism, see ZAP authenticated
       connection sample below.

RETURN VALUE

       The zmq_msg_gets() function shall return the string value for the property if successful. Otherwise it
       shall return NULL and set errno to one of the values defined below. The caller shall not modify or free
       the returned value, which shall be owned by the message. The encoding of the property and value shall be
       UTF8.

ERRORS

       EINVAL
           The requested property is unknown.

EXAMPLE

       Getting the ZAP authenticated user id for a message:.

           zmq_msg_t msg;
           zmq_msg_init (&msg);
           rc = zmq_msg_recv (&msg, dealer, 0);
           assert (rc != -1);
           const char *user_id = zmq_msg_gets (&msg, "User-Id");
           zmq_msg_close (&msg);

SEE ALSO

       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 4.1.4                                          12/18/2015                                    ZMQ_MSG_GETS(3)