Input device design

[Joe Krahn]

Russell Shaw wrote:
...
>  > There also needs to be a generic client/server protocol for input
>  > devices, which can be used to connect remote devices, emulate devices,
>  > or provide a way to connect new hardware that does not yet have proper X
>  > driver support. Something like UPnP is needed, but UPnP is overly
>  > complex for simple input device purposes, and still incomplete. Also, MS
>  > has a patent for device communication via XML. I was thinking of a
>  > trivial UPnP-like protocol using ConciseXML. ConciseXML is less verbose,
>  > and is IMHO a better fit to data than is regular XML, plus helps avoid
>  > conflicts with the UPnP people and/or the MS patent.
> 
> IMHO, it's a crappy idea to use verbose textual xml for communication
> protocols. It's best for what it was designed: inter-application 
> portability
> of data, such as between word processors. Internal to an application 
> like X,
> a fast and compact (maybe even binary) purpose-built protocol optimized for
> the application should be used.
> Also, X should stay scaleable to small embedded devices, which precludes
> throwing in gobs of xml parsers. Gtk going to xml to configure menus peeved
> me off no-end:(

Jim Getty's suggested XML, with the argument that input-event data is 
small enough that the overhead/waste is minimal. I'm suggesting 
ConciseXML because it's less overly-verbose than 'real' XML.

A binary alternative could probably be based on this: 
http://home.ifi.uio.no/~dinkoh/

IRIX uses a shared-memory queue to feed event data to X. Maybe some 
ideas could be gotten from looking at IRIX.

Joe