Unstable protocol name breakage

[Mariusz Ceier]

Hi,

On 20 October 2015 at 04:22, Jonas Ådahl <jadahl at gmail.com> wrote:

> Hi again,
>
> I was about to start migrating generic protocols away from weston into
> wayland-protocols. The idea was to start with input-method.xml, text.xml,
> linux-dmabuf.xml, presentation_timing.xml, scaler.xml and xdg-shell.xml.
> The
> question, however, is what to do with the names, because some names already
> have the form "wl_[name]", and renaming such an interface to "zwl_[name]1"
> during the unstable period, and then back to "wl_[name]" will cause
> potential
> breakage because some implementations in the wild might expect the
> "wl_[name]"
> to be the original (ancient) version.
>
> As mentioned before, I have already moved the fullscreen shell protocol,
> and
> with the naming schema changes in place, it ended up with the protocol name
> "fullscreen-shell-unstable-v1", the interfaces zwl_fullscreen_shell1, and
> zwl_fullscreen_shell_mode_feedback1.
>
> linux-dmabuf.xml is also easy. Since it is already 'z' prefix, to comply
> with
> the intended naming schema, I'd just need to rename the interfaces to
> zlinux_dmabuf1 and zlinux_buffer_params1, and the protocol to
> linux-dmabuf-unstable-v1.
>
> presentation_timing.xml: I suppose this one can be renamed without any
> significant implications, since it currently is completely prefix free. I
> imagine it'd be zwl_presentation1 and zwl_presentation_feedback1 in a
> presentation-timing-unstable-v1(.xml) protocol.
>
> The problem is the rest of the protocols, since they all already have the
> intended stable names. This means we cannot apply a naming schema that
> intends
> to finally remove the prefix and postfix when declaring stable, since that
> would collide with the initial name. How to deal with these names needs to
> be
> decided, and probably so protocol by protocol.
>
> scalar.xml: As far as I know, Pekka has plans to change scalar.xml, and
> plan to
> do so with a name change. So as far as I understand, we need to rename this
> one.
>
> input-method.xml: This one I think might actually be fine to just apply the
> naming schema, as the protocol itself has Wayland core principle violations
> that need to be solved, i.e. any implementor of this is already broken (by
> principle).
>
>
Since it's broken by principle, can't input-method.xml be marked as
deprecated (e.g. by implementing/using top-level deprecated attribute ) ?
Then leave it in weston as weston-specific protocol, that generates
deprecation warnings during compilation and maybe when used by clients
connecting to weston; and in wayland-protocols add new protocol that's not
broken by principle (but may be based on input-method).

Deprecation can also be used for other problematic protocols, but I'm not
sure if that's good idea if such protocol is not broken.

text.xml: This one I'm not so sure about. Has it ever been implemented
> outside
> of weston except only as a proof of concept? Would it be fine to use the
> same
> name?
>
> xdg-shell.xml: Should we bite the bullet and rename this one, or just
> continue
> letting its stability state be non-discoverable? It's clearly already
> used, and
> renaming it will be painful, so not sure about this one.
>
>
Maybe we should at first stabilise protocols that are used, not broken and
renaming them will be painful ?


> Then comes the IVI protocols. I have no opinions about these, and I don't
> know
> what any plan with them might be. Should they be moved, or are they purely
> a
> weston thing?
>
> For the rest of the protocols (desktop-shell.xml, screenshooter.xml,
> text-cursor-position.xml, weston-test.xml, workspaces.xml) I plan to leave
> them
> be, as they either are purely weston internal, simple toy protocols or
> have no
> consesus that they are to be ever be official protocols.
>
> So what should we do about these naming issues? It should have been clear
> that
> all of these are experimental protocols, but due to the fact that some may
> have
> started to use these outside of weston anyway even though they being
> experimental, is it Ok for us to start causing them to break? If not, what
> may
> some alternative names be?
>
>
> Jonas
>


Mariusz Ceier
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