Re: Application Launch Detection

[julian adams <julian adams gmx net>]

At 16:01 14/11/2000, Mary Dwyer wrote:
> hi
>
> I haven't fallen off the email thread - I've been keeping track of the 
> ideas put
> forward and trying to get a picture of what is wanted and how it could be
> implemented.
>
> The current thread seems to be:
>
> 1. avoid use of LD_PRELOAD
> 2. do not patch Xlib

As well as technical concerns there's issues of protocol compatibility. 
We're really talking about patching XFree86, not Xlib. Even if this were 
technically the right thing to do (no comment on that), this would only 
reach people running XFree, at least in the short term. I imagine revising 
the X protocol would be a) tedious, b) slow and c) not something to do for 
a small change. I think this would reach less people more slowly than 
working at the toolkit (preferably) or app (if you must) level.

> 3. concentrate on establishing a common protocol that will work for both 
> gnome
>    apps and KDE apps (ie KDE apps running under gnome will use gnome visual
>    feedback, and vice versa)

The only thing missing from your summary was Havoc's suggestion that we 
define 2 methods:

Method 1) For new / current  apps - possibly to be implemented by the 
toolkits. This would require implementation, and would not support any 
legacy binaries, but would work with 100% of new apps (that chose to 
support it).

Method 2) For existing binaries - this would have to be "hackier", and 
would probably not work with 100% of apps, ever. I don't see this as a 
problem, just as long as crahses are never caused (LD_PRELOAD !!). If 
method 1) is simple enough and we provide a reference implementation in C 
which only relies on Xlib I don't think that legacy (read closed source and 
unmaintained) apps will persist for that long. Sometimes i think that too 
much time is spent on legacy apps.



>  - To achieve this ensure that gnome apps set the value of the 
> _NET_WM_PID atom
>    on the first window they map (as do KDE apps).
>
>  - Then a Gnome Launcher process can monitors the _NET_CLIENT_LIST property
>    on the root window. It checks the _NET_WM_PID property of each window 
> and
>    stops the matching visual feedback.
>
>    Essential to this is starting a feedback instance identifiable by the PID
>    of the app being launched.
>    But I cannot figure out how/where to start the feedback display instance
>    for the app., i.e. how does the Launcher know the PID of the app being
>    started? If you launch the feedback display from within the gnome 
> application
>    (eg from gnome_init()) then you lose interoperability with KDE apps.
>
>    I guess I don't fully understand how the KDE app-launcher starts 
> the
>    feedback.  Rik's mail to wm-spec-list outlining how it works
>
> (http://mail.gnome.org/archives/wm-spec-list/2000-September/msg00000.html)
>    specifies that
>    "the executable is started and the pid of the running process is noted 
> ....
>    .... then a signal is sent to the panel's taskbar object, informing it 
> of the
>    name of the application and the pid".
>
>    Could you give some more detail on how this is done? (bearing in mind 
> I know
>    very little about KDE :-( )
>
>    But, am I right in assuming from the various emails that this is the 
> way
>    forward on this? ie
>    - in coming up with a solution going forward, ignore legacy apps as 
> well as
>      non-gnome and non-KDE apps (and possibly do a hack for these sort of 
> apps)
>    - ensure that gnome apps set the _NET_WM_PID property
>    - have a Launcher process separated totally from the apps, that
>      starts an instance of feedback identified by the PID of the app
>      being launched (how to do this?).
>    - The Launcher then monitors the _NET_CLIENT_LIST property on the root
>      window in order to stop the feedback instance when the app is mapped.
>
> If I have picked things up wrong from the emails on this please set me
> right :-)
> I am far from being an expert in Xlib or window manager work, but I would 
> very
> much like to be involved in working on a mechanism for Application Launch
> Feedback in gnome.
>
>
> thanks
> Mary
>
> ~ I speak for myself, not for my employer ~
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> Mary Dwyer
> Desktop Applications & Middleware Grp
> Sun Microsystems Ireland
> Tel: +353-1-8199222 (xt 19222)
> email: mary dwyer ireland sun com
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>
>
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