binary protocol notes from the facebook hackathon

Dustin Sallings dustin at
Wed Jul 11 17:38:54 UTC 2007

On Jul 11, 2007, at 10:29 , Brad Fitzpatrick wrote:

> If you don't know a command, and how to parse said unknown command,  
> why do
> you care about finding the key?

	In the case I ran into, I was processing a lot of the command in  
lower-level code.  I could hand the command ID, opaque, key, and  
extra data to the higher level protocol handler and let it deal with it.

	Currently, I register extra header decoders by command ID and do the  
same type of split, but unrecognized commands will have to be handled  
slightly differently.

	The theoretical case is the wireshark protocol plugin.  When quiet  
set gets added sometime after the memcached binary protocol plugin,  
it'd be easy enough to remember that command n is quiet set, and have  
it show you the flags section, key, and data.

	Of course, in a command that is unfamiliar to the reader doesn't,  
the flags and data would be completely meaningless.

Dustin Sallings

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