Splitting KGlobalAccel interface and runtime

[Kevin Ottens]

Hello,

On Monday, 13 February 2023 21:25:54 CET Vlad Zahorodnii wrote:
> On 2/13/23 22:05, Nicolas Fella wrote:
> > Hi,
> > 
> > the kglobalaccel framework currently contains two pieces: kglobalacceld,
> > the runtime component that manages global shortcuts, and an
> > application-side library to interact with it.
> > 
> > The two communicate with each other via DBus. On X11 there is a
> > standalone kglobalacceld5 process providing the interface, on Wayland
> > the runtime is linked into KWin and thus the kwin_wayland process
> > provides the interface.
> > 
> > The current architecture has a number of downsides:
> > 
> > - Any call to the KGlobalAccel library may DBus-activate the
> > kglobalacceld5 process, which may be undesired on Desktop other than
> > Plasma since it competes with their native shortcut system. We tried
> > fixing that by making such calls no-op on !Plasma, but that broke things
> > for people that did want it to run, for example people using KWin with
> > LXQt, because KWin relies on KGlobalAccel for shortcuts
> > 
> > - We want to keep the dependencies of the interface library minimal,
> > which is inconvenient for the development of the runtime part. For
> > example we really want to use KIO::ApplicationLauncherJob in the
> > runtime, but currently can't, because that would introduce a dependency
> > cycle in Frameworks (KIO depends on KXmlGui, which depends on
> > KGlobalAccel, which would depend on KIO)
> > 
> > - Coinstallability of KF5 and KF6. Conceptually there can only be one
> > kglobalacceld. If both KF5 KGlobalAccel and KF6 KGlobalAccel install a
> > kglobalacceld this is going to be problematic. This also means that a
> > KF6-based kglobalacceld must work with a KF5 interface library
> > 
> > - Other shortcut daemon implementations. Since somewhat recently there
> > is an XDG Portal for global shortcuts. Platforms like Windows and macOS
> > also have ways for applications to register global shortcuts. While we
> > are currently not using any of these it's very well possible that we
> > would eventually want to use the KGlobalAccel interface library to
> > interact with those. Having the kglobalacceld runtime in the same
> > frameworks therefore doesn't feel right.
> > 
> > To address these issues I suggest we split out the runtime part of
> > kglobalaccel into its own project, under the Plasma release group,
> > because that's primarily where it's used/supported. The interface
> > library would remain in frameworks. We have a similar situation with
> > activities, where the manager (kactivitymanagerd) is in Plasma and the
> > interface is in Frameworks. When doing this we'd also change the way how
> > kglobalacceld is started away from DBus activation towards explicitly
> > starting it as part of the Plasma startup. This avoids accidentally
> > launching it when it shouldn't be but still allows to explicitly start
> > outside of Plasma if really wanted. It would also allow for greater
> > flexibility in the development of the runtime, especially around
> > dependency constraints.
> > 
> > It wouldn't automatically solve the coinstallability problem of KF5 and
> > KF6, because a kglobalacceld provided by KF5-KGlobalAccel would still
> > conflict with a Plasma-provided kglobalacceld, but it's at least
> > conceptually less messy since it's clear that the Plasma-provided one
> > would be the preferred one to use.
> > 
> > Thoughts about this?
> 
> +1
> 
> There's one caveat though: given that the library and the runtime parts
> will have different release schedules, we will have to be careful about
> protocol changes. Perhaps we could borrow a thing or two from activities?

Or... move both runtime and API on the Plasma side? This way no problem of 
different release schedules and it makes it clear that using it ties you to a 
specific desktop anyway?

With a quick grep it looks like most of the users are already shipped with 
Plasma or desktop specific anyway. Granted that leaves with a couple of tough 
nuts to crack though.

Regards.
-- 
Kevin Ottens, http://ervin.ipsquad.net

enioka Haute Couture - proud supporting member of KDE
https://hc.enioka.com/en
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