Registration

FOSDeM has no formal registration and name tags, which appeared to be a good thing, as there were many more visitors this year (around 1400 on the first day alone) than last year (around 300). With 1400 people, registration processing might take forever.

Open Protocols and Data Formats

Due to getting lost earlier, I dropped in late on Tim O Reilly’s talk. "The Internet is open source’s biggest success […] open protocols and data formats are even more important than open source".

I felt right at home, as my colleagues at CQ2 are completing the implementation of the OA-x (Open Archive extended) protocol and data format.

Contemplating on this, I see that open protocols and data formats are more accessible than open source - since you can choose whichever programming language and operating system you want to make use of the protocol and the data (TCP-IP and e-mail being succesful examples of this). Even if one part of the protocol is complex (i.e. The ‘google server’) you can write a simple client (google access with soap) re-using the implementation and installation complexity someone else has resolved for you.

For I-tor this might mean the amount of people working on the i-tor server might remain small - since it contains a lot of advanced features not always needed, while other people might more easily make clients for editing specific kinds of OA-x documents, or make simple servers publishing and storing documents in OA-x format. The i-tor server acts as an intermediary for combining collections of oa-x documents, publishing them through a web-interface and allowing them to be queried interactively by end-users.

Ruby

I went to Richard Kilmer’s talk on Ruby , to see how someone who uses it everyday presents it, and to pick up some stuff I might have missed. New stuff I picked up from this talk:

• YAML (included in ruby 1.8) - a non-XML human readable/editable serialization format for ruby and perl. The library uses ruby’s class extension facilities effectively - after loading YAML all your objects have a ‘to_yaml’ method. YAML is made for readability and ease of use. Existing serialisation methods are more efficient.
• ROMP - "(the Ruby Object Message Proxy) is a set of classes for providing distributed object support to a Ruby program."

ROMP does the same as DRB (Distributed Ruby), but is much more efficient according to Rich Kilmer. (I couldn’t get more than 50 messages a second out of DRB, but apparently, there now is a faster version. ROMP handles up to 40000 messages per second). It is also very easy to use - with a few lines of ruby, you can make an object available on a tcp port. Using ROMP seams a decent way of splitting presentation from storage of objects. The server stores objects and deals with concurrency, and several presentation server applications and threads can access the objects.

Ruby-GNOME

This talk was on the integration of Ruby with GTK libraries. The design of GNOME is interesting, since it is highly plugin-oriented, with a pipes-and-filters like architecture for multimedia applications. The ruby-bindings convinced me less, since creating a GUI is doable, but requires double steps - the GUI ends up in a separate configuration file from the code, and the names of events have to be specified twice. For small applications, such as the media player that was demonstrated, this is doable. For larger applications I foresee it will be difficult to keep an overview on everything defined.

ReiserFS - the fast pluggable filesystem

Hans Reisers’ talk on ReiserFS once again proves that good design and high performance software are not opposites, but go hand in hand. ReiserFS version 4, to be released this week, features plugins for various aspects of the filesystem, from allocating blocks, to storing individual files. The reason for the plugin architecture was, as mr. Reiser said, that optimizing a filesystem is an empirical science. You need to try something at least three times, fail two times and then find a better solution. The plugins allow many people to try out their hypotheses. The ReiserFS distribution can then include the most succesful plugins.

One of the plugins planned for the near future is compressed files (like e.g. Atacker in the old days, only more reliable), since disk speed has not kept up with cpu speed increases, this will allow for faster disk (read) access. To me it seems a good solution for storing XML files… Another thing which is easy to do with plugins is encryption.

The vision behind ReiserFS is also interesting - the file system should take care as much as possible for things like atomicity, so applications built on top of it can be as simple as possible. ReiserFS is intended to replace databases as a means of storing many small objects - it does not allocate a lot of space for individual files anymore, so it is possible to efficiently store each object in its own file, even if it is just a few fields of data. ReiserFS takes care of efficiently storing all the objects. The explanation of ‘dancing trees’ (a variation on B-Trees) was interesting. A file system is basically a huge map, with file-id’s as keys, and file data as values.

Concerns influencing the design of ReiserFS, such as plugins and granularity of security are familiar to me, since we face them in designing I-Tor as well, so maybe a close mapping on ReiserFS could enhance performance (small objects optimized by the filesystem) and facilitate development (atomicity, security).

Frequent releases

Agile Software development things like frequent releases come through. I was talking to the GNOME packager for MandrakeSoft at dinner, and he said they recently switched to weakly developer releases, regardless of content (just release frequently), and every 6 months there is an end-user release, where stable features are chosen and released. API’s can change every 6 months, old methods are deprecated and kept for one more release, ensuring a stable application development environment, as well as evolution of the API’s.

Summary

FOSDEM is an interesting conference for free and open source software developers. You can quickly get an idea what is going on in major open source projects. Also, many groups take the opportunity to actually develop software together in the developers’ rooms for specific projects.