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diff --git a/doc/zmq_msg_send.txt b/doc/zmq_msg_send.txt new file mode 100644 index 0000000..1056e60 --- /dev/null +++ b/doc/zmq_msg_send.txt @@ -0,0 +1,125 @@ +zmq_msg_send(3) +=============== + + +NAME +---- +zmq_msg_send - send a message part on a socket + + +SYNOPSIS +-------- +*int zmq_msg_send (zmq_msg_t '*msg', void '*socket', int 'flags');* + + +DESCRIPTION +----------- +The _zmq_msg_send()_ function is identical to linkzmq:zmq_sendmsg[3], which +shall be deprecated in future versions. _zmq_msg_send()_ is more consistent +with other message manipulation functions. + +The _zmq_msg_send()_ function shall queue the message referenced by the 'msg' +argument to be sent to the socket referenced by the 'socket' argument. The +'flags' argument is a combination of the flags defined below: + +*ZMQ_DONTWAIT*:: +For socket types (DEALER, PUSH) that block when there are no available peers +(or all peers have full high-water mark), specifies that the operation should +be performed in non-blocking mode. If the message cannot be queued on the +'socket', the _zmq_msg_send()_ function shall fail with 'errno' set to EAGAIN. + +*ZMQ_SNDMORE*:: +Specifies that the message being sent is a multi-part message, and that further +message parts are to follow. Refer to the section regarding multi-part messages +below for a detailed description. + +The _zmq_msg_t_ structure passed to _zmq_msg_send()_ is nullified during the +call. If you want to send the same message to multiple sockets you have to copy +it using (e.g. using _zmq_msg_copy()_). + +NOTE: A successful invocation of _zmq_msg_send()_ does not indicate that the +message has been transmitted to the network, only that it has been queued on +the 'socket' and 0MQ has assumed responsibility for the message. You do not need +to call _zmq_msg_close()_ after a successful _zmq_msg_send()_. + + +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 sends multi-part messages must use the _ZMQ_SNDMORE_ flag +when sending each message part except the final one. + +RETURN VALUE +------------ +The _zmq_msg_send()_ 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 the message cannot be sent at the moment. +*ENOTSUP*:: +The _zmq_msg_send()_ operation is not supported by this socket type. +*EFSM*:: +The _zmq_msg_send()_ 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 linkzmq: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 the message was +sent. +*EFAULT*:: +Invalid message. +*EHOSTUNREACH*:: +The message cannot be routed. + + +EXAMPLE +------- +.Filling in a message and sending it to a socket +---- +/* Create a new message, allocating 6 bytes for message content */ +zmq_msg_t msg; +int rc = zmq_msg_init_size (&msg, 6); +assert (rc == 0); +/* Fill in message content with 'AAAAAA' */ +memset (zmq_msg_data (&msg), 'A', 6); +/* Send the message to the socket */ +rc = zmq_msg_send (&msg, socket, 0); +assert (rc == 6); +---- + +.Sending a multi-part message +---- +/* Send a multi-part message consisting of three parts to socket */ +rc = zmq_msg_send (&part1, socket, ZMQ_SNDMORE); +rc = zmq_msg_send (&part2, socket, ZMQ_SNDMORE); +/* Final part; no more parts to follow */ +rc = zmq_msg_send (&part3, socket, 0); +---- + + +SEE ALSO +-------- +linkzmq:zmq_recv[3] +linkzmq:zmq_send[3] +linkzmq:zmq_msg_recv[3] +linkzmq:zmq_socket[7] +linkzmq: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>. |