diff options
| -rw-r--r-- | doc/zmq_getsockopt.txt | 17 | ||||
| -rw-r--r-- | doc/zmq_recv.txt | 37 | ||||
| -rw-r--r-- | doc/zmq_send.txt | 33 |
3 files changed, 85 insertions, 2 deletions
diff --git a/doc/zmq_getsockopt.txt b/doc/zmq_getsockopt.txt index 13243ec..4aef71c 100644 --- a/doc/zmq_getsockopt.txt +++ b/doc/zmq_getsockopt.txt @@ -24,6 +24,23 @@ to by 'option_value'. The following options can be retrieved with the _zmq_getsockopt()_ function: +ZMQ_RCVMORE: More message parts to follow +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The 'ZMQ_RCVMORE' option shall return a boolean value indicating if the +multi-part message currently being read from the specified 'socket' has more +message parts to follow. If there are no message parts to follow or if the +message currently being read is not a multi-part message a value of zero shall +be returned. Otherwise, a value of 1 shall be returned. + +Refer to linkzmq:zmq_send[3] and linkzmq:zmq_recv[3] for a detailed description +of sending/receiving multi-part messages. + +Option value type:: int64_t +Option value unit:: boolean +Default value:: N/A +Applicable socket types:: all + + ZMQ_HWM: Retrieve high water mark ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The 'ZMQ_HWM' option shall retrieve the high water mark for the _message queue_ diff --git a/doc/zmq_recv.txt b/doc/zmq_recv.txt index 879d62a..b93f2a5 100644 --- a/doc/zmq_recv.txt +++ b/doc/zmq_recv.txt @@ -29,6 +29,23 @@ associated with 'socket', the _zmq_recv()_ function shall fail with 'errno' set to EAGAIN. +Multi-part messages +~~~~~~~~~~~~~~~~~~~ +A 0MQ message is composed of 1 to N message parts; each message part is an +independent 'zmq_msg_t' in its own right. Consequently, wherever this +documentation uses the term _message_ it may be substituted for _message part_. + +An application wishing to determine if a message is composed of multiple parts +does so by retrieving the value of the _ZMQ_RCVMORE_ socket option on the +'socket' it is receiving the message from. If there are no message parts to +follow, or if the message is not composed of multiple parts, _ZMQ_RCVMORE_ +shall report a value of zero. Otherwise, _ZMQ_RCVMORE_ shall report a value of +1, indicating that more message parts are to follow. + +0MQ shall ensure the atomicity of a multi-part message; peers shall receive +either all _message parts_ of a multi-part message or none at all. + + RETURN VALUE ------------ The _zmq_recv()_ function shall return zero if successful. Otherwise it shall @@ -47,7 +64,7 @@ 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 associated context was terminted. +The 0MQ 'context' associated with the specified 'socket' was terminated. EXAMPLE @@ -63,10 +80,28 @@ rc = zmq_recv (socket, &msg, 0); assert (rc == 0); ---- +.Receiving a multi-part message +---- +int64_t more; +do { + /* Create an empty 0MQ message to hold the message part */ + zmq_msg_t part; + int rc = zmq_msg_init (&part); + assert (rc == 0); + /* Block until a message is available to be dequeued from socket */ + rc = zmq_recv (socket, &part, 0); + assert (rc == 0); + /* Determine if more message parts are to follow */ + rc = zmq_getsockopt (socket, ZMQ_RCVMORE, &more, sizeof more); + assert (rc == 0); +} while (more); +---- + SEE ALSO -------- linkzmq:zmq_send[3] +linkzmq:zmq_getsockopt[3] linkzmq:zmq_socket[7] linkzmq:zmq[7] diff --git a/doc/zmq_send.txt b/doc/zmq_send.txt index 927bc1b..b05c73b 100644 --- a/doc/zmq_send.txt +++ b/doc/zmq_send.txt @@ -23,12 +23,34 @@ Specifies that the operation should be performed in non-blocking mode. If the message cannot be queued on the underlying _message queue_ associated with 'socket', the _zmq_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. + NOTE: A successful invocation of _zmq_send()_ does not indicate that the message has been transmitted to the network, only that it has been queued on the _message queue_ associated with the socket and 0MQ has assumed responsibility for the message. +Multi-part messages +~~~~~~~~~~~~~~~~~~~ +A 0MQ message is composed of 1 to N message parts; each message part is an +independent 'zmq_msg_t' in its own right. Consequently, wherever this +documentation uses the term _message_ it may be substituted for _message part_. + +An application wishing to send a multi-part message does so by specifying the +'ZMQ_SNDMORE' flag to _zmq_send()_. The presence of this flag indicates to 0MQ +that the message being sent is a multi-part message and that more message parts +are to follow. When the application wishes to send the final message part it +does so by calling _zmq_send()_ without the 'ZMQ_SNDMORE' flag; this indicates +that no more message parts are to follow. The total number of mess + +0MQ shall ensure the atomicity of a multi-part message; peers shall receive +either all _message parts_ of a multi-part message or none at all. + + RETURN VALUE ------------ The _zmq_send()_ function shall return zero if successful. Otherwise it shall @@ -47,7 +69,7 @@ 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 associated context was terminted. +The 0MQ 'context' associated with the specified 'socket' was terminated. EXAMPLE @@ -65,6 +87,15 @@ rc = zmq_send (socket, &msg, 0); assert (rc == 0); ---- +.Sending a multi-part message +---- +/* Send a multi-part message consisting of three parts to socket */ +rc = zmq_send (socket, &part1, ZMQ_SNDMORE); +rc = zmq_send (socket, &part2, ZMQ_SNDMORE); +/* Final part; no more parts to follow */ +rc = zmq_send (socket, &part3, 0); +---- + SEE ALSO -------- |