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Coding The Future Linux Desktop [updated]
the.jedi writes "With the release of GTK+ 2.4, and Gnome 2.6 due out some time next week, it seems of some the Gnome developers are looking at how they'll be coding Gnome and the rest of the Linux desktop. Havoc Pennington of Planet Gnome has written a short blog pondering and analyzing the available options as coders move towards high-level languages like java and C#. He gives a good overview and assessment of technologies like mono, OO.org's UNO framework, as well as other ways of tying new languages to the existing code base. An extremely interesting read for desktop linux hackers everywhere."
Update: 03/17 14:44 GMT by T : Speaking of the future of Gnome, aeneas writes with a list of Gnome 2.6 release parties around the world (linked from gnome.org/start/2.5).
I'm not favoring XUL, but if I read ok, the article mention sthat XUL only has bindings to javascript. These are maybe the best implmented, but ti has also bindings (or being worked on) for perl, python and ruby.
Michel
A big part of the slowness of gtk2 is font rendering. Motif uses (or used?) XDrawString(), so text was done entirely by the server. On the downside, the quality of the text rendering was very poor.
gtk2 draws all text with pango. Pango is a high-quality unicode text renderer with an Xft2 backend. If you have an old X server, this can be pretty slow. If you have a recent XRender extension, it's almost as fast as the old XDrawString().
Owen Taylor did add an optimisation to render text more quickly for text which gtk knows is being drawn over a plain background, this helps old X servers a lot, provided you're not using a pixmap-based theme.
At 8mb on my system (that includes the java class library) that's pretty light. For comparison .NET on Windows weighs in at about 30mb and the Mono RPM (compressed) is about 8mb as well, so it's certainly competitive.
I'll try to address some of the issues Havoc presented. Of course, I'm a Mono developer, so I'm biased, but hopefully people can see my arguments are more on the technical side than advocacy.
No rewrites please: this is a very important point: we can't just throw away the current code: we need incremental changes to not disrupt stability and compatibility. I'll just note that using Mono (and C#), interoperability with existing C code is much easier than with Java because of P/Invoke.
Calling managed code from C/C++: Havoc says it's hard, but Mono provides an easy to use interface to do that. Mono is designed to be embedded in existing applications, not just as a runtime for standalone completely managed programs. Also, it would be easy to create a shared library and header files to access managed methods seamlessly: they can be automatically generated thanks to the use of Reflection and the Mono embedding API.
I'm not sure a "simple native component system bridge" would solve the issues, mostly because simple systems are always found later to be incomplete, they get changed and become big, but with all the design warts needed to make a simple design work for not-so-simple constraints.
A minimal Mono system is currently about 2 MB on disk, but no effort yet has been put into reducing it (and I think it's entirely possible, we have been busy implementing features and leaving aside space optimizations). Of course, since the default build of the core assembly has lots of features, much of the reduction in size could be achieved by trimming features that other systems don't have:-). Even without trimming, most people will concour that 2 megabytes of disk space for a shared component is small enough in a desktop setting (and applications compiled to IL code are usually much smaller than comparable C apps anyway).
Community should decide: of course, I agree. Anything that is pushed down our throats by somebody else is not going to work for the free software and open source communities. The solution will need to be choosen because it actually solves issues the developers and the users see. Java had several years to try to attract developers from our community and it had some success in some niche areas (not for desktop applications, though). Mono has just started, but from the comments of the developers that actually used it to write new applications or port existing ones from C, it looks like we are on a good adoption path (even though we didn't release a 1.0 version yet, we are still working on debugging support and documentation is sparse).
Havoc fears the adoption of Mono or Java for the desktop would alienate people and cause forks. I don't think that will happen with Mono, because Gnome will continue to have a diversity of developers who'll prefer using the C libraries directly: Mono allows to keep and interoperate with existing code very easily and we want the migration to happen incrementally, so at first only end-user applications would be written in managed code, while the foundation would still be in C (at least, enough of the foundation to have people happyly writing their own apps in c or with the existing bindings). At that point, when a managed execution environment has proven itself to both developers and users (hopefully) we could start discussing about using it for the foundation, too, if that makes sense. I think Mono is positioned better here to allow this incremental shift of both development and espectations towards a managed runtime.
Problems with a .Net clone: Havoc claims that MS controls the platform
because, even if the core is unencumbered, some assemblies are tied to MS
technologies and there is non standards body or community momentum to build
alternative solutions for a complete platform. Well, considering that until
a couple of months ago there were 5 people developing mono, we have achieved a lot,
not only in the implementation of the runtime, but also, thanks to the large
commun