[Xcb] EWMH API for XCB

Jamey Sharp jamey at minilop.net
Thu Dec 17 09:56:05 PST 2009

On Wed, Dec 16, 2009 at 10:19 PM, Barton C Massey <bart at cs.pdx.edu> wrote:
> I don't recall that there's anything in the X Protocol Specification
> that prevents servers from hardwiring atoms other than the standard
> ones. ... As long as the server correctly responds to intern_atom
> requests for the hardwired atoms, you should be good.

That's right, as far as I know.

> Just the presence of an extension with the right version number (e.g.
> a sufficiently advanced MISC extension) could indicate this. ... The
> primary benefit would be killing one or more round trips...

As Rémi said, all those InternAtom requests are batched into a single
round-trip, so you need something with zero round-trips to win on
latency. A protocol version bump is the only way to get that, I think,
although it could possibly be a minor version bump as Alan suggested.

The only advantage of an extension is a bandwidth savings, and the
disadvantages are having to decide which atoms are worthy of being
included in an extension, and having to take at least one extra
round-trip if the extension isn't available. In fact I think an
extension would require two round-trips even in the success case: one
for QueryExtension and another for the extension's QueryVersion, or some
similar second request to decide which atoms are available.

I've added notes at the X12 page about how I think I'd handle this.


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