FOSS.in Day 1 (Project Day 1)
So, here is a report of foss.in Project Day 1. Colin, Aizatto and yours truly decided on attending the Mozilla Project Day. It started off by a short introduction by Mary Colvig from Mozilla Corporation.
Oh the places you’ll go! (things you can do with firefox extensions)
Myk Melez then started off Firefox extensions “Oh the places you’ll go! (things you can do with firefox extensions)”. He stated that extensibility (via extensions) wasn’t an accident as Netscape originally wished to add proprietary functionality to an open source browser. In that vein, Firefox 1.0’s goal was to simplify browsing experience and evolve extension capabilities, allow additional hooks, have better extension management and have an extension directory list.
Firefox 1.5 to Firefox 3.0 goal’s were/are to have an integrated manager, localizable descriptions, a Firefox user extension library and a review process for extensions.
Myk then gave an overview of javascript front-end and back-end functionality and components. Some examples shown were the Stumbleupon extension (which adds/modifies new functionality within the browser), the Alexa plugin (to extend websites), a download manager (to enhance existing functionality), resizeable form fields (hacking web pages) and showed snap links (being able to open multiple links by dragging links into tabs, very very nice I must say).
During the audience Q&A, the audience requested a torrent downloading system, an addon’s manager within the browser and search engine optimization within Firefox. Based on the discussion, it seems that this set of functionality should be easily possibly within Firefox.
Personal thoughts: This was a fairly introductory talk, IMHO. Some of the functionality shown (resizeable form fields, snap links) would certainly be of interest to web developers and possibly extension developers.
Writing applications with Mozilla Framework
Prasad Sunkari spoke next on application development using the Mozilla framework. The Mozilla development platform offers user interface widgets and implementations, XUL, huge collection of widgets, javascript for implementing the user interface, CSS for skinning and styling. It is even possible to use templates and bindings (to implement a custom widget) and that the data source (rdf) can create part of the user interface). He then covered overlays, components, the utility library and portability issues. That was followed by a small “Hello World” type tutorial.
In the Q&A, there were questions on the perceived large runtime (for a comparatively small application). The feedback to that was that the size of XULrun is 3 or 4 megabytes and is certainly much smaller then ActiveX. Futhermore, like Java, the same instance of XULrunner can run many other software. It was also mentioned that Firefox 3 will run have a XULrunner-like software installed by default.
Personal thoughts: I’ve done Firefox extension development before, so there was little new information in this talk for me. However, I would imagine those wishing to get involved in Firefox development would find the talk illuminative.
An introduction to XPConnect (writing extensions in pure JavaScript)
Anant Narayanan spoke on cross platform application development in Mozilla using XPconnect. XPConnect has components (network, DOM, mail, UI, data structures etc) and is basically the the JavaScript interface to XPcom. As such, any JavaScript that runs in the Mozilla environment will have access to all XPcom components (although only those components which have interfaces defined in xpidl will be available).
Anant then outlined some development tools including Firefox itself, Console Squared, FireBug, JSlib and XPcomviewer and Exten Generator.
Anant described XPcom components being available as native JavaScript objects, with each component being identified by a contract ID. Instantiatin a component involves calling the getService() method with passing an interface along as an argument. Anant showed a code snippet on a simple logging class and javascript loader. Useful would be in avoiding namespace clashes by putting stuff into object as there are some global objects mozilla introduces (for example Components).
jsLib seemed to be particularly interesting, with lots of repetitive tasks and frequently used components in JavaScript already written.
Personal thoughts: I found jsLib particularly interesting and probably would be looking into it much deeper soon-ish. The talk was decent enough although I wish the talk had gone a little deeper into code.
Hunting Bugs
We didn’t fancy the other talks in the Mozilla Project Day and decided to move on to the GNOME Project Day. Ritesh Khadgaray was speaking on bug hunting so we thought that may be interesting.
Ritesh started off by giving a list of things that can go wrong in the code, what can be dont (RTFM’s, visiting forums, BugZilla, looking at the code, looking at release notes and so on). He then outlines the GNOME session flow and strangely enough, his laptop hangs at this point (because of none-free NVIDIA driver). Despite calls for him to fix it at that point, a cold reboot was required and fortunately, things looked fine at that point. He went on to give an example of ESD hanging using strace and went on to show the use of GDB.
Personal thoughts: I didn’t find this talk particularly interesting as I pretty much knew everything mentioned (having being involved in free software for some time now). Of course, YMMV 
The challenges and opportunities of properly writing multi-threaded GTK based GNOME programs
Andrew Cowie spoke on how to correctly write multi-threaded GTK based GNOME programs. He started off by why GTK rocks: fast, flexible, ubiquitous, multiplatform, many language bindings and LGPL’ed licensed. In particular, he highlighted that multi-threading is important in dual-core machines.
At this point, he showed us how to turn off a single cpu in a dual-core machine (and thus saving 3 watts of power). Apparently, the magic is in /sys/devices/system/cpu/cpuX. Using the GNOME system monitor, he showed us a Fibonnaci generator program which clearly showed the use of a single core in a dual-core machine for a non-threaded application.
Andrew indicated that writing multi-threaded code is hard (no shit!) but clearly necessary in some types of applications (think GUI applications). In GTK, the main loop polls sources for events (events being user activity, I/O, timeouts etc) and events are issued as named signals. As such, a GTK developer ought to register callbacks for signals the application should react to.
Andrew showed an example of the GUI blocking (eg when suspended). He mentioned that one way to solve GUI blocking is to have an idle function handler but program would still be single threaded. GTK is actually “thread aware” which is significant given that GTK was originally written to be singly threaded. He then walked through a multithreaded GTK application.
Personal thoughts: Good talk, perhaps some discussion on avoiding common threading pitfalls would useful.
Day 2 feedback would be up soon-ish.