JAN
24
2007

The Road to KDE 4: Job Progress Reimagined

Have you ever had your taskbar filled with 10 applications all
doing something that involved waiting for a task to finish?
Document Printing Progress, a K3b CD burning dialogue, Audio Encoding
via KAudioCreator, File Transfers in Konqueror, Kopete, KTorrent,
checking email in KMail... The new Jobs support in KDE 4 will unify
the display of progress for these tasks, making it easy to see and manage what is happening on your system. Read on for details.

Picture it as a cross between the Firefox download manager and
the KDE printer queue, except that there is no real restriction on
what type of jobs can be monitored. The way it works is that each
KDE 4 app that has a progress dialog adds a flag for
something called an Observer. Then, a separate application can observe any running Jobs, displaying progress and even adding
certain actions (like "Cancel Download") which can be submitted back
to the application that actually has the progress dialog. So the
applications like K3b, which already have very good progress
reporting, will not lose their existing dialogs, but rather additionally permit this new applet to observe its progress so that all the progress bars can be pulled into a convenient place.

What started as a
mocked up KDE 4 Improvement
via KDE-Look.org has turned into a
full-fledged KDE 4 integration project, thanks to Rafael Fernandez Lopez.
And there's been a lot of progress to the point where applications
are already being adapted to the new infrastructure. Last
Tuesday's "Binary Incompatible Changes" day saw much of the changes
officially committed to the KDE 4 repository.

Below is the original mock up, done by KDE user and KDE-look.org
contributor
kiras
, used with permission. Click to see the full-sized
mockup.

Please keep in mind that the above is a mockup, and does not
necessarily reflect the ultimate look-and-feel goals of KDE 4,
Plasma or Konqueror.

Currently, it is being prototyped as a standard system tray applet
(similar to the printer queue in KDE 3.5.5) which would allow
interoperability with GNOME's tray implementation as well. However, at this point only KDE applications can be observed, so monitoring download
progress from Firefox for instance, is not currently supported. That is not to
say it cannot be made to happen in the future since progress is observed using the standard D-Bus interprocess communication architecture. There are intentions to collaborate with the GNOME project's Mathusalem team, a
project of similar scope as this one.

Here is a screenshot of the current appearance of the monitoring
application as it would appear when clicking on the tray applet. As
you can see, it's already looking very useful.

As you can see, the Kopete buttons are mostly just placeholders
at the moment, and only exist for testing purposes. However, when
you click on one of those buttons, it actually sends a signal back to Kopete,
and Kopete itself pops up that smaller dialog you see.

The Konqueror download progress bars you see being monitored represent
an actual file download in progress. They continue even after Konqueror
is closed. Useful action buttons like "Abort Download" are in the
works.

If you'd like to get involved in KDE 4 development, adding
support for the new KJobs progress monitoring is a fairly easy entry
point to KDE programming. It takes only a few lines of code to
adapt an application to display progress, and a few more lines to
make the action buttons useful.

This new progress monitoring technology will be able to be
integrated into Konqueror (like in the mockup), desktop applets, and
anything else that uses D-Bus. I can even imagine a small web-app
that lets you monitor progress remotely...

Rafael's goal after the initial implementation is completed is to
add persistence, such that when a job is complete, it would
optionally stay listed until closed by the user. He is also looking
for feedback on this tool and its implementation for future improvements.

Look forward to more feature articles showcasing more great
technologies for KDE 4.

A quick note on methodology: I make sure to use the KDE defaults for all of my screenshots, even if it's ugly, since then you can get a better sense of progress as KDE 4 evolves and grows from week to week. As a rule, all of the
features I've demonstrated so far are publicly available in SVN, and
anyone can reproduce my results. In today's article, I had to
uncomment a single line of code to enable this in-development
feature, which is an exception to my normal rules. Additionally,
the Kopete progress support is not yet in the official KDE SVN repository, but Rafael uses it to test features.

Comments

This job progress interface can also be used to simply play a soundfile from the file manager, without opening a bloated media player with playlists and such, right?

As far as I understand, the interface even supports buttons, such as pause and seek (for example the "Pause" and "Cancel" buttons in the dialog for the download of "install-x86-universal-2005.1.iso" in the screenshot).


By Erik at Sat, 2007/08/25 - 5:00am

Looking sweet, and something I have wanted for a long time. However, the mockups, while looking good, do waste a lot of screen space and could be smaller.

Also, without knowing anything about the underlying API's, it would be nice if it was possible to hook into it and listen to the status information. For instance, it would allow such things as adding LED bars on the computer case as status bars. Not only practical, but cooler than a great white shark with shades.


By Anders Troberg at Wed, 2007/09/19 - 5:00am

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