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Diffstat (limited to 'doc/zmq_send_const.txt')
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diff --git a/doc/zmq_send_const.txt b/doc/zmq_send_const.txt new file mode 100644 index 0000000..38033f9 --- /dev/null +++ b/doc/zmq_send_const.txt @@ -0,0 +1,103 @@ +zmq_send_const(3) +================= + + +NAME +---- +zmq_send_const - send a constant-memory message part on a socket + + +SYNOPSIS +-------- +*int zmq_send_const (void '*socket', void '*buf', size_t 'len', int 'flags');* + + +DESCRIPTION +----------- +The _zmq_send_const()_ function shall queue a message created from the buffer +referenced by the 'buf' and 'len' arguments. The message buffer is assumed +to be constant-memory and will therefore not be copied or deallocated +in any way. 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_send_const()_ 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. + +NOTE: A successful invocation of _zmq_send_const()_ 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. + + +Multi-part messages +~~~~~~~~~~~~~~~~~~~ +A 0MQ message is composed of 1 or more message parts. 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_send_const()_ 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_send_const()_ operation is not supported by this socket type. +*EFSM*:: +The _zmq_send_const()_ 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. +*EHOSTUNREACH*:: +The message cannot be routed. + + +EXAMPLE +------- +.Sending a multi-part message +---- +/* Send a multi-part message consisting of three parts to socket */ +rc = zmq_send_const (socket, "ABC", 3, ZMQ_SNDMORE); +assert (rc == 3); +rc = zmq_send_const (socket, "DEFGH", 5, ZMQ_SNDMORE); +assert (rc == 5); +/* Final part; no more parts to follow */ +rc = zmq_send_const (socket, "JK", 2, 0); +assert (rc == 2); +---- + +SEE ALSO +-------- +linkzmq:zmq_send[3] +linkzmq:zmq_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>. |