RDA3 Transport Joel Lauener on behalf of the CMW team 26th June, 2013
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Introduction Provide connection management and asynchronous bi-directional communication Keep it simple & stupid! Abstraction of the underlying communication library Independent from other librairies 2 Introduction
Transcript of RDA3 Transport Joel Lauener on behalf of the CMW team 26th June, 2013
• Introduction• Architecture• Connection management• Messaging• Conclusions
Outline
1
Introduction
• Provide connection management and asynchronous bi-directional communication
• Keep it simple & stupid!• Abstraction of the underlying communication
library• Independent from other librairies
2
Introduction
Public API
3
Architecture
Dispatcher
• Push sockets from high level to transport• Callback from transport to high level
4
Architecture
Channels
• Admin socket:– Management– Small message size– Small message count
• Data socket:– Application data– Might block/overflow
5
Architecture
Frames
0x20 CLIENT_CONNECT0x21 CLIENT_REQ0x22 CLIENT_HB
0x01 SERVER_CONNECT_ACK0x02 SERVER_REP0x03 SERVER_HB
6
Architecture
Message
• Used to pass data between high layer and transport layer
• Wrapper around ZMQ message with custom free function
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7
Architecture
Connect (success)
8
Connection Management
Heartbeating
9
Connection Management
Connect (fail)
10
Connection Management
Client reconnect
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Connection Management
Server disconnect
12
Connection Management
Client close
13
Connection Management
Connection states
14
Connection Management
Request
15
Messaging
Replies
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Messaging
• Each data point can be multiplexed• Authorization layer (RBAC)• Cannot send first updates through the same
channelWe do not use pub/sub for notifications
• But we have 2 use cases for a pub/sub based transport: Timing and Orbit Feedback
What about pub/sub?
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Messaging
• Powerful, easy to use, well documented• However…– In terms of error handling ROUTER is inconsistent
compared to DEALER, REQ and REP– ZMQ doesn’t give means to inspect/modify the
content of queues
ZeroMQ
18
Conclusions
Future plans
• Improve disconnection detection on the server side (ZMQ monitor or async HB)
• Implement graceful close• Investigate pub/sub• Think about replies priority• Performance testing and profiling• Should be ready by September ’13
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Conclusions
• Transport is almost implemented– Working version in C++ and Java– 90% done, 90% of work left ;)– Some work left on error detection
• Pub/sub is not used for sending notifications• No showstoppers on the ZeroMQ side• Preliminary scalability tests are promising
Summary
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Conclusions
