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view docs/extension-pingpong.txt @ 10:36c4cda4b6c4
Add extension support with the PINGPONG extension
Add extension support. There are two ways to add extensions:
1. as a shared object which will be loaded with ext=<filename> as a
parameter to lwwire. See the lwwire_pingpong.c file for details.
2. By doing basically the same thing as a shared object but linking it into
the main binary and calling lwwire_register_extension() appropriately.
| author | William Astle <lost@l-w.ca> |
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| date | Sat, 30 Jul 2016 13:16:39 -0600 |
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This document describes an extension to the LWWire protocol which provides a "PINGPONG" facility. It does not provide a generally useful service. However, it does serve to show how a basic extension can be defined. It also gives clients an option to enable an extension and use that to determine if the server has reset or otherwise got into a mixed up state. For instance, the client could negotiate the PINGPONG extension and then periodically send a PINGPONG_PING operation. If it doesn't get the appropriate response, it can then assume that the server has reset and it should re-initialize its drivers. LWWire Protocol Extension ========================= This extension is called PINGPONG and is assigned extension number DF. It defines the following operations in its extension space. 00 PINGPONG_PING This does just what it's name implies. It does nothing except reply to the client. Request: Octet Meaning ----- ------- 0-2 F3 DF 00 Response: Octet Meaning ----- ------- 0 42 The response will always be 42. 01 PINGPONG_PONG This is exactly like PINGPONG_PING. It's provided for humour value. Request: Octet Meaning ----- ------- 0-2 F3 DF 01 Response: Octet Meaning ----- ------- 0 42 The response will always be 42.