[Mageia-dev] Fwd: Reviving AppStream and current status

Tue Mar 20 21:23:00 CET 2012

Very interesting message sent by Vincent Untz (SUSE) about the AppStream 
+project (remember, when misc, Nanar and myself went to Nuremberg on SUSE's 
+invitation to discuss cross-distro application installers?), its status and 
+things we could do in every distribution.
+
+I definitely hope we can do it for Mageia 3!
+
+The summarize:
+* produce the appdata.xml metadata files automatically and publish them on the 
+mirrors
+* extract icons from packages and put them in icons packages (one per media)
+* write data export script for distromatch
+* start playing with the forked Software Center with packagekit back-end
+* host a debshots instance for our screenshots / help developing it 
+(currently, Mageia App Db uses screenshots from screenshots.debian.net, but in 
+the long run maybe we want our own screenshots database for use in both madb 
+and the software center if we choose to use it)
+
+Best regards
+
+Samuel Verschelde
+
+----------  Message transmis  ----------
+
+Sujet : Reviving AppStream and current status
+Date : mardi 20 mars 2012
+De : Vincent Untz <vuntz at gnome.org>
+À : distributions at lists.freedesktop.org
+
+Hi all,
+
+A small group discussed AppStream last year, and the result was archived
+at http://distributions.freedesktop.org/wiki/AppStream
+
+There was a nice timeline, but then everyone got busy :/ So it got stuck
+a bit (except for distromatch, thank to Enrico!)
+
+A few weeks ago, some of us took some time to get appstream back on
+track. There are still many things to do, but I guess it's a good time
+to talk about the current status since there's something starting to
+work.
+
+There is a "How can I help?" section at the end :-)
+
+
+Software Center with PackageKit support
+=======================================
+
+Last year, Alex Eftimie did a GSoC project to land a PackageKit backend
+in the software center. This was some good preliminary work, but still
+needed some love, especially in terms of performance.
+
+The code is now alive again, and lives in git at
+https://gitorious.org/appstream/software-center
+
+Unfortunately, because of the Harmony CLA required by Canonical, some of
+us can't contribute the changes back to the original software center
+project (for instance, I'm not fine with the CLA so won't sign it).
+Therefore this is becoming a fork; that being said, we're trying to stay
+in sync with the launchpad code, and Michal Hrušecký is merging the code
+from launchpad trunk every now and then. The goal of the fork is not to
+substantially diverge, but simply to make the software center usable on
+all distros.
+
+It's reaching the point where it's usable, however there is still a road
+ahead before this becomes usable by everyone:
+
+ - some external tool needs to be used to fetched appdata.xml, and call
+   the update-software-center tool to generate the xapian database
+
+ - only the basic features have been tested; I'm not completely sure the
+   channel-related features work well, for instance; also package
+   updates haven't been tested
+
+ - several features (recommendations, reviews) need to be re-implemented
+   for distros (more on this below)
+
+ - the current code is pretty much synchronous, which is a bit ugly
+
+Of course, to play with the software center in an AppStream context, we
+need some application metadata (appdata.xml) :-)
+
+
+Application metadata
+====================
+
+openSUSE is now generating an appdata.xml file for its repo. You can
+find an example here:
+  http://download.opensuse.org/factory/repo/oss/suse/setup/descr/appdata.xml.gz
+
+It'd be great to have other distros generate this too so everyone can
+play with the PackageKit backend in the software center (although Debian
+and Ubuntu can still use the apt backend).
+
+That being said, in the short term, it can already be used on other
+distro, or even better, we can use distromatch to transform it to work
+for other distros.
+
+There's also a tarball with icons:
+  http://download.opensuse.org/factory/repo/oss/suse/setup/descr/app-
+icons.tar.gz
+It's not used by the software center yet; the way files are arranged
+inside this tarball is pretty much still to be defined.
+
+
+Features based on web services
+==============================
+
+Several features depend on external services: screenshots,
+recommendations, reviews, etc.
+
+For screenshots, the plan is to use debshots:
+  http://debshots.workaround.org/
+There's currently a 2.x version being written, that will have
+multi-distribution features, see
+  http://workaround.org/pipermail/debshots-devel/2012-March/000004.html
+So this is looking good :-)
+
+For recommendations and reviews, well, I'm not aware of anyone working
+on this. So that's a hole we need to fill; it could possibly be a GSoC
+project.
+
+
+"How can I help?"
+=================
+
+We want this project to succeed and be usable by all distros, and to
+achieve this, we need your help! Without you, things won't move as fast
+as they should ;-)
+
+Here are the different areas where people can step up and rock the
+world:
+
+ - Get code to generate distromatch data for your distro
+   => This can be used to generate an appdata.xml file for all distro
+      supported in distromatch, based on an appdata.xml file from one
+      distro. And this will be usable in debshots and other services
+      later on.
+   => We already have code for Debian, Fedora, openSUSE and Ubuntu, but
+      we'd need more.
+   => An export script for your distro is writable in a few hours. See
+      as example the existing scripts:
+      https://gitorious.org/appstream/distromatch/trees/master/scripts
+   => For reference, here's a tarball containing Fedora and openSUSE
+      data (it will move to a proper home at some point):
+      http://tmp.vuntz.net/misc/distromatch/distromatch-opensuse-fedora.tar
+
+ - Get some appdata.xml file published in your distro repository
+   => This is something that needs to be plugged in the build service of
+      each distro.
+   => The scripts we use to extract the data after the build of
+      packages in openSUSE can be found at:
+      https://build.opensuse.org/package/files?package=brp-extract-
+appdata&project=openSUSE%3AFactory
+      It's unclear to me if this can be reused by other distros, though.
+
+ - Test the PackageKit-based software center on your distro (and hack on
+   it so that it's rock-solid!)
+   => Clone the code:
+      git clone git://gitorious.org/appstream/software-center.git
+   => You can start with a dummy appdata.xml file (see
+      https://gitorious.org/appstream/resources/blobs/master/appdata.xml
+      for an example).
+   => To use the code from the checkout:
+      # Generate xapian database from appdata.xml
+      ./utils/update-software-center --local --appstream-only
+      ./software-center
+   => You might need to create a backend for your distro; this is very
+      simple, see files in ./softwarecenter/distro/
+
+ - Help develop debshots 2.x
+   => Join http://workaround.org/cgi-bin/mailman/listinfo/debshots-devel
+
+ - Volunteer to work on the reviews and recommendations services
+   => The client code in the software center can be analyzed to show the
+      needs we have.
+   => This should be created with multi-distribution features in mind,
+      like debshots.
+
+Cheers,
+
+Vincent
+
+-- 
+Les gens heureux ne sont pas pressés.
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+-------------------------------------------------------
+