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Diffstat (limited to 'doc/zmq_device.txt')
| -rw-r--r-- | doc/zmq_device.txt | 60 |
1 files changed, 14 insertions, 46 deletions
diff --git a/doc/zmq_device.txt b/doc/zmq_device.txt index 6026559..10d7445 100644 --- a/doc/zmq_device.txt +++ b/doc/zmq_device.txt @@ -13,8 +13,7 @@ SYNOPSIS DESCRIPTION ----------- -The _zmq_device()_ function starts a built-in 0MQ device. The 'device' -argument is one of: +The _zmq_device()_ function starts a built-in 0MQ device. The 'device' argument is one of: 'ZMQ_QUEUE':: starts a queue device @@ -23,86 +22,55 @@ argument is one of: 'ZMQ_STREAMER':: starts a streamer device -The device connects a frontend socket to a backend socket. Conceptually, data -flows from frontend to backend. Depending on the socket types, replies may -flow in the opposite direction. +The device connects a frontend socket to a backend socket. Conceptually, data flows from frontend to backend. Depending on the socket types, replies may flow in the opposite direction. -Before calling _zmq_device()_ you must set any socket options, and connect or -bind both frontend and backend sockets. The two conventional device models -are: +Before calling _zmq_device()_ you must set any socket options, and connect or bind both frontend and backend sockets. The two conventional device models are: *proxy*:: - bind frontend socket to an endpoint, and connect backend socket to - downstream components. A proxy device model does not require changes to - the downstream topology but that topology is static (any changes require - reconfiguring the device). + bind frontend socket to an endpoint, and connect backend socket to downstream components. A proxy device model does not require changes to the downstream topology but that topology is static (any changes require reconfiguring the device). *broker*:: - bind frontend socket to one endpoint and bind backend socket to a second - endpoint. Downstream components must now connect into the device. A - broker device model allows a dynamic downstream topology (components can - come and go at any time). + bind frontend socket to one endpoint and bind backend socket to a second endpoint. Downstream components must now connect into the device. A broker device model allows a dynamic downstream topology (components can come and go at any time). -_zmq_device()_ runs in the current thread and returns only if/when the current -context is closed. +_zmq_device()_ runs in the current thread and returns only if/when the current context is closed. QUEUE DEVICE ------------ -'ZMQ_QUEUE' creates a shared queue that collects requests from a set of -clients, and distributes these fairly among a set of services. Requests are -fair-queued from frontend connections and load-balanced between backend -connections. Replies automatically return to the client that made the original -request. +'ZMQ_QUEUE' creates a shared queue that collects requests from a set of clients, and distributes these fairly among a set of services. Requests are fair-queued from frontend connections and load-balanced between backend connections. Replies automatically return to the client that made the original request. -This device is part of the 'request-reply' pattern. The frontend speaks to -clients and the backend speaks to services. You should use 'ZMQ_QUEUE' with a -'ZMQ_XREP' socket for the frontend and a 'ZMQ_XREQ' socket for the backend. -Other combinations are not documented. +This device is part of the 'request-reply' pattern. The frontend speaks to clients and the backend speaks to services. You should use 'ZMQ_QUEUE' with a 'ZMQ_XREP' socket for the frontend and a 'ZMQ_XREQ' socket for the backend. Other combinations are not documented. Refer to linkzmq:zmq_socket[3] for a description of these socket types. FORWARDER DEVICE ---------------- -'ZMQ_FORWARDER' collects messages from a set of publishers and forwards these -to a set of subscribers. You will generally use this to bridge networks, e.g. -read on TCP unicast and forward on multicast. +'ZMQ_FORWARDER' collects messages from a set of publishers and forwards these to a set of subscribers. You will generally use this to bridge networks, e.g. read on TCP unicast and forward on multicast. -This device is part of the 'publish-subscribe' pattern. The frontend speaks to -publishers and the backend speaks to subscribers. You should use -'ZMQ_FORWARDER' with a 'ZMQ_SUB' socket for the frontend and a 'ZMQ_PUB' socket -for the backend. Other combinations are not documented. +This device is part of the 'publish-subscribe' pattern. The frontend speaks to publishers and the backend speaks to subscribers. You should use 'ZMQ_FORWARDER' with a 'ZMQ_SUB' socket for the frontend and a 'ZMQ_PUB' socket for the backend. Other combinations are not documented. Refer to linkzmq:zmq_socket[3] for a description of these socket types. STREAMER DEVICE --------------- -'ZMQ_STREAMER' collects tasks from a set of pushers and forwards these to a set -of pullers. You will generally use this to bridge networks. Messages are -fair-queued from pushers and load-balanced to pullers. +'ZMQ_STREAMER' collects tasks from a set of pushers and forwards these to a set of pullers. You will generally use this to bridge networks. Messages are fair-queued from pushers and load-balanced to pullers. -This device is part of the 'pipeline' pattern. The frontend speaks to pushers -and the backend speaks to pullers. You should use 'ZMQ_STREAMER' with a -'ZMQ_PULL' socket for the frontend and a 'ZMQ_PUSH' socket for the backend. -Other combinations are not documented. +This device is part of the 'pipeline' pattern. The frontend speaks to pushers and the backend speaks to pullers. You should use 'ZMQ_STREAMER' with a 'ZMQ_PULL' socket for the frontend and a 'ZMQ_PUSH' socket for the backend. Other combinations are not documented. Refer to linkzmq:zmq_socket[3] for a description of these socket types. RETURN VALUE ------------ +<<<<<<< HEAD The _zmq_device()_ function shall not return if successful. Otherwise it shall return `-1` and set 'errno' to one of the values defined below. ERRORS ------ -*ETERM*:: -The 0MQ 'context' associated with the specified 'frontend' or 'backend' was -terminated. -*EFAULT*:: -The provided 'frontend' or 'backend' was not valid (NULL). +The _zmq_device()_ function always returns `-1` and 'errno' set to *ETERM* (the 0MQ 'context' associated with either of the specified sockets was terminated). EXAMPLE |