[Xcb] [RFC v0 proto] Add XInput2 protocol description

Peter Harris pharris at opentext.com
Mon Dec 3 13:21:35 PST 2012

On 2012-12-03 16:05, Daniel Martin wrote:
> (In the following I'll write "XI2" when I mean the XInput extension
> starting with version 2.0 and "XI" for the version up to 1.5.)
> On Mon, Dec 03, 2012 at 09:56:26AM -0500, Peter Harris wrote:
>> On 2012-12-02 16:05, Daniel Martin wrote:
>>> Add the XInput2 protocol description for reviewing and feedback.
>> I haven't had time to review the meat of this, but this stuck out on an
>> initial glance:
>>> +	xinput2.xml \
>>> +<xcb header="xinput2" extension-name="Input2"
>>> +     extension-xname="XInputExtension" major-version="2" minor-version="2">
>> That's the same extension-xname as xinput.xml. I suspect the new
>> definitions should be in xinput.xml, not in their own file.
> I've choosen to make it in a seperate file, cause the extension name is
> nearly the only thing both versions have in common and XI2 superseeds
> the functionallity provided by XI.

Except for the QueryVersion request, which is only present in the XI1
description. I suppose it could be duplicated in xinput2.xml, but see below.

> Supporting both versions is not necessary as the XI specification
> states:
>     "... New clients are discouraged from using this protocol
>          specification. Instead, the use of XI 2.x is recommended. ..."
> Mixing both versions in one file would cause to much confusions on the
> (library) user side, as he wouldn't know which request is for which
> version without having a look at the specification.
> Due to that, the fact that the protocol description for XI is not
> complete and XI is disabled by default in libXCB, I would rather mark it
> as deprecated when this XI2 protocol description becomes usable. But, I
> wouldn't like to merge them.

Be that as it may for libxcb, the Wireshark dissector generator is not
expecting to find the same extension spread out over multiple files.

If we deprecate xinput.xml, we can move QueryVersion into xinput2.xml.
But that leaves Wireshark without support for older (XI1) clients.

I'd generally prefer to keep the special cases to a minimum, but it's
not all that much work to add extension merging (especially if you don't
duplicate any requests) to the Wireshark generator. Before I do that,
I'd like to hear if anybody else has an opinion on this topic.

 Peter Harris
               Open Text Connectivity Solutions Group
Peter Harris                    http://connectivity.opentext.com/
Research and Development        Phone: +1 905 762 6001
pharris at opentext.com            Toll Free: 1 877 359 4866

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