"List all Tabs" in Firefox 7 has different backgrounds for onscreen and off-screen tabs

A few days ago, my Firefox automatically updated to version 7.0.1 and ever since it's one new feature (which hasn't been advertised as a feature at all) has been bugging me; because I was not able to understand what it does.!. The feature in question is the different background color for some tabs in the "List All Tabs" menu - The menu that you get when you click the small (almost inconspicuous) inverted triangle between the "New Tab" (+) and the "Window minimize" (-) buttons.

The first time I saw the differential background I thought it was like the read and unread tabs, like one of the tab management add-ons does. But no. No matter how many times I read the page in a tab, it's background color did not change.

The next thought was that it corresponded to background tabs which are lazily loaded, i.e. the page is not actually loaded from the internet until you bring that tab to focus. But no, it was not even this. Even after several visits some tabs stayed with dark background.

No amount of searching on the internet helped at that time and I had to calm myself down and let go off the quest for this eternal answer. Finally today I gave it another shot with some variations in search strings and I landed on this page which lists all the changes in version 7.0. Here I started searching for any bug related to tabs and finally got the right bug. This bug states the purpose of differential background color in the tabs list.

As the bug states, the dark colored (highlighted) tabs are the ones which are currently displayed on the screen in the tab bar and the light colored ones are scrolled off the screen (horizontally). The rationale is that, this will make it very easy to figure out where a particular tab that you are looking for is, in case you are confused about it's position.
I am yet to see the feature being actually useful. Nevertheless, for the moment I am happy that I know what the feature does. :)

Mozilla @ SJCE : Static Analysis projects

It has been a very long time since I posted anything about the Mozilla related activities going on at my college SJCE, Mysore. That in no way means absence of any activity. In a previous post I mentioned that along with the attempt to introduce Mozilla as a standard course I was working to get the current final year students (who are enrolled under the larger VTU University) to start working on Mozilla, using their final semester project as a means. Well I am happy to say that this has materialized. 8 final semester students from CS expressed interest in working with the Mozilla community as part of their final year project and it's been a month nearly since they started their work. Here is a brief write up about that.

As is with most of the Computer Science students in India approaching the Mozilla community, these 8 students also wanted to do something related to compilers. The JS engine and static analysis are two projects in Mozilla which would come under the compiler banner. These 8 students wanted to work on something substantial which can be presented by two teams of 4 students each as their final semester project. So the bugs that they would be working on had to be related. This was possible only with static analysis as there are a lot of related tasks available. Also static analysis would be something new to the students and it would give them an opportunity to understand the internals of the compiler (GCC here) like the AST (Abstract Syntax Tree) and other representations of the code. Moreover the static analysis APIs are exposed in JS and hence the analysis scripts would be written in JS. That way students would learn JS also. Above all these students would be doing something genuinely new.

The students could not be asked to start working on the bugs directly. They were new to open source development, the tools used there like the bugzilla, using email as a formal medium of communication, the source control system (to add to the complexity Mozilla now uses a distributed RCS - Mercurial [hg]), using IRC, the linux development environment etc. It has been these things that the students have been learning for this part month or so. This learning has been in the form of accomplishing the tasks which form the prerequisites for the actual static analysis work. These are things like downloading gcc and mozilla sources from the ftp hosts and from the mercurial repository respectively, applying the mozilla specific patches to gcc for plugin support etc, etc... These are all listed here. Note that some things like installing all the dependency packages for building these applications from sources, learning to use the linux command line itself and others are not on that page but were new to these students nonetheless.

All the students have been putting in substantial effort and have picked up the traits of an open source hacker pretty soon. We have had a few IRC meetings and a lot of formal communications over emails. In parallel we were also working towards shortlisting 8 static analysis bugs. Based on the feasibility of the bug being completed by an amateur developer within a span of 2.5 months and based on the students' interest we finally decided on these 8 bugs :

1. Bug 525063 - Analysis to produce an error on uninitialized class members
   
2. Bug 500874 - Static analysis to find heap allocations that could be stack allocations
   
3. Bug 500866 - Warn about base classes with non-virtual destructors
   
4. Bug 500864 - Warn on passing large objects by value
   
5. Bug 528206 - Warn on unnecessary float->double conversion
   
6. Bug 526309 - Basic check for memory leaks
   
7. Bug 542364 - Create a static analysis script for detecting reentrancy on a function
   
8. Bug 500875 - Find literal strings/arrays/data that should be const static
   

These tasks are good, challenging and provide an opportunity to understand compilers very closely.

Currently the students have downloaded gcc, applied the patches, built it along with the dehydra plugin support and are ready to run static analysis on the mozilla code. They are now trying to run simple analysis scripts like listing all classes in mozilla code and all classes and their corresponding member functions. It is still quite a long way to go, but it has been a real good start. Let's wait and watch what great feats are in the pipeline.

I hope to keep this blog updated at the same pace at which the students are working.

Good luck to the students. :-)

Script to get nsIWebProgressListener state names from state codes

This is totally Mozilla specific and probably will not make any sense to anyone not involved with Mozilla code.

So in Mozilla there is an interface named nsIWebProgressListener which can be used to get notifications about any web progress -- a page load in simple terms. So these notifications are sent to us by calling our onStateChange methods. One of the parameters passed is the state of the request. This is a hex code. Memorizing all the hex codes is insane. So to log the states I wrote a small, dumb, script.

I wanted to put it somewhere on the internet, instead of a file on my disk, and hence this blog post. Here is the script to convert nsIWebProgressListener state hex codes to state names. A simple lookup function, but handy for logging

var flagNames = [
"STATE_START",
"STATE_REDIRECTING",
"STATE_TRANSFERRING",
"STATE_NEGOTIATING",
"STATE_STOP",
"STATE_IS_REQUEST",
"STATE_IS_DOCUMENT",
"STATE_IS_NETWORK",
"STATE_IS_WINDOW",
"STATE_RESTORING"
]

var flagValues = [
0x00000001,
0x00000002,
0x00000004,
0x00000008,
0x00000010,
0x00010000,
0x00020000,
0x00040000,
0x00080000,
0x01000000
]

function splitFlags(aFlag) {
var states = ""
for(var i in flagValues)
{
if(aFlag & flagValues[i])
{
    states+= flagNames[i] + "\n";
}
}
return states;
}

That's it.

Mozilla @ SJCE -- Contributing to Mozilla informally - Final semester student projects

Along with the attempt to introduce Mozilla as a formal elective at SJCE I have been working on getting some development work started informally too. The current final year students are enrolled under the central university - VTU and hence cannot be offered any new subject. However they are expected to do a project as part of the course completion. I thought of using this to get students to do their final semester project with Mozilla. Also Mozilla labs organizes this program named Design Challenge where enthusiasts -- students, teachers, academicians, software developers, etc, are invited to submit innovative ideas to make the Firefox web browser a better software and the Internet in general a better place. This has received tremendous participation from the student community across the globe. The best part about this program is that this is not just a competition. The selected students are trained on various Mozilla related technologies by the very Mozilla developers who are developing those technologies. After such mentoring the students can start contributing code to Mozilla and products based on it. And not to mention the wealth of knowledge they stand to gain and how much of positive influence it will have with prospective employers or while applying for higher studies. This suited very well for the final year and also the pre-final year students.

So when I visited my college last Saturday (14-Nov-2009) to meet my HoD and the coordinating lecturer, related to the Mozilla elective to be offered, I decided to talk to final and pre-final year students and motivate a few of them to participate in the upcoming design challenge (Nov - 09 to Mar - 10) and also take up Mozilla work for final year projects. I talked to the coordinating lecturer (Shri P M Shivamurthy) and asked to him make an announcement regarding this and have the students assembled in one of the classrooms or the seminar hall. After going to the college I got to know that the pre-final year (5th sem) students would not be available as they have their internal assessment tests starting from Monday. HoD suggested that I should stay back till Monday evening and address the 5th sem students on Monday after that day's tests. That was not possible for me and I decided to visit the college again on the next Saturday for that and I would talk to the final year (7th sem) students for now. As a result I decided to stick to the final year project only. Things were set up in the Network Lab and there were about 30 students.

Standing in front of them I blabbered a bunch of things about Mozilla, Open Source software, how engineers graduating are not really industry ready and the fact that they do not have any experience on working with real world applications with huge code base and contributions from a large number of developers and finally how participating in Mozilla would help them fill that gap. I also told them the vast amount of options that Mozilla provides in terms of technologies and that they could find some work or the other which lies in their area of interest. At the end I asked if anyone had any questions and as expected nobody did. Then on asking how many would be willing to try something like this I saw something like 3 to 4 half-hands rising up in the air. This was certainly not a good sign. So I started with the "motivational" speech. "This will really help you guys to be ahead of students from other colleges. You will be industry ready where as other will require a lot more training and mentoring. This is all HoD pre-approved... and on and on and on" for a few more minutes. That really did the trick. After this I had about 10 - 12 hands, full ones. Quite satisfied I told them to get my contact details from PMS sir and contact me for any queries. Till now I have received emails from 6 students (one of them representing a project group of 4 students. so 9 students actually). I have sent them a couple of links to start reading. None of them have responded after that. But I am still hopeful.

A little later I was talking to some of the students offline and I got to know some facts which would have been very useful to me in positioning this Mozilla project idea in a much stronger way.

1) Campus recruitment is pretty bad this time. Only 6 students in Computer Science have got job offers, compared to a daily average of 20 - 25 students a couple of years back. --- I could have talked about how open source development experience will help them with jobs. It did help me.
2) Project teams (generally of 3 to 4 students) have already been formed and a guide (a member of the faculty) has been assigned. This has two effects:
    a) Some teams have already been given the project work, which is a small part of the guide's doctorate thesis/research. The guide will now not happily approve of students under him/her pursuing a difference project.  -- We could talk to HoD and reason out with the guide. I could have told the students that such a thing is very much possible.

    b) In a project team of 4, generally one or two students are the smart ones and others will be banking on them for the project to be completed. I had told them that in Mozilla it is generally individual contribution or a team of 2 at the max. The teams, like those mentioned earlier, cannot be divided as the dependent folks will get into a problematic position. -- I could have told them that Mozilla does not bother if the work done by one student is present by 4 as a team work. So let the team enroll for a Mozilla project. Either all or a few in the team will work. If its all of them each one will have a bug assigned or the bug will be assigned to one guy with all of them working on it. If it is just one or two of them then there are no issues.

    c) On a related not to the above two points, some students told me that they would like to do a Mozilla project in addition to an already assigned final semester project. This really delighted me. But it also was, sort of, a matter of concern, as it appeared to me that people were desperate to do something like this with the hope that it will add a line to their resume and help them get a job. I might be wrong and I wish and hope I am. Students doing open source development just out of pure interest and not part of any course requirements is the best thing. But let me see what it turns out to be.

3) I did not make an announcement about the design challenge because the mentoring classes for that goes on from Dec-09 to Feb - 10 and these guys have their exams in the second  half of December. But I later got to know that no mentoring classes will be held from approximately 21st Dec to 4th Jan because of the holiday season in the US. So I talked to a smaller number guys, those who stayed back to talk to me, about the design challenge and am hoping to have 1 to 3 ideas being submitted.

I am going to use these points during my next visit, this coming Saturday.

Mozilla @ SJCE -- Modern teaching methods are still a stigma and considered unreliable.

In my effort to get open source development into main stream academics at my engineering college SJCE, I have been working with the Mozilla Education team for some time now. With our college getting the autonomous status and also with great help from the MozEdu folks like Prof David Humphrey and Frank Hecker and after considerable persuasion (more about that in a different post) I could get an elective named "Learning Open Source Software with Mozilla" added to the curriculum of the 6th semester students. We (me and the members of the college faculty) decided to roll out this elective in the year of 2010. The next step for me, I thought, was to get at least one lecturer trained with the curriculum and in general get that lecturer involved with Mozilla development and practices. Also with Prof David making the videos of his lecture sessions available on the internet, freely for everyone's use, my plan was to give the lecturer a head start (w.r.t students) so that with the beginning of the next semester he could start teaching the students those parts which he has already learnt. In the mean time he himself can continue his learning by going through David's lecture sessions and other resources that would be available on the internet. I would be visiting the college on alternate weekends. I thought, may be I could take a couple of hours of classes on Saturday for both students and also the lecturer(s). I could have used my presence to answer the queries that the students and the lecturers had, or at least I could point them in the right direction. Apart from these fortnightly visits I planned to be in touch with the college folks continuously on the internet -- email, irc, skype, etc. I would be actively involved the first time this subject is taught. After that the lecturer would be considerably capable and also the subsequent batch of students would have their seniors to help them out. At that point the program will not greatly depend on me and will be sort of self-sufficient with people directly talking to the Mozilla developers and the community in general. As a bonus the students who studied this subject would get to carry out their final year project work with Mozilla, either in terms of some feature implementation or certain bug fixes or any such task. It appeared like a sound plan and I had even decided that we would try to get about 15 students for the first time and gradually increase the number.

Last Saturday (14-Nov-2009) I went to meet the HoD and the lecturer who was coordinating this from the college side to get things started. The meeting was a big disappointment. Our HoD made it absolutely clear that the this elective will be offered only if 50% of the students (which translates to about 70 - 80 students) take up the elective. So the idea of first starting with a small number so that coordinating things on the internet will be easier and all that was just blown away. The reason for this is apparently because there are not enough class rooms to teach more than 2 groups of students from the same semester.!! It has to be a 50-50 division between two electives. So though there are 5 or 6 electives available to the students, they actually have to choose from just 2 of them, based on the majority and not interest.

Well my plan was not killed completely, yet, as the ideas in it were sort of the perfect solution for "the lack of classrooms" problem. I put forth the rest of my idea saying the remote teaching and a lot of learning on an individual basis (by reading up the resources on the internet and interacting with the Mozilla devs) would virtually the necessity of a full blown class room teaching always. But the HoD flatly rejected this idea and said that he understood what I was suggesting but there are rules saying classes must be conducted for a fixed number of hours for any subject offered and it has to be the traditional way. Also the idea of training the lecturers in a, sort of, asynchronous manner was also not acceptable. He would want a training session to be conducted - typically a week to a month long session, may be with a certification at the end of the session. Moreover currently I have one lecturer ready to take this up but department mandates at least 2 or 3. Now I have an additional task of motivating at leat two more faculty members. For this I have to prepare a write up explaining what the lectures stand to learn/gain by taking up this new thing. After that if any of them express their interest in taking this up, I will have to train them and probably it has to be in the traditional way - not sure yet.

Another problem is the pace. The next semester will be starting some time in Feb or Mar 2010 and my HoD keeps saying "Lets go slowly at first and see. If not in 2010 we will offer this in 2011" !!.. :-( . I hope we can get this thing started in 2010 itself. Another year of idle waiting might just terminate the interest that I currently have.

All in all, the wall between open source and my college is appearing to be more and more thick. I intend to meet the HoD the coming Saturday again and try to convince him to give his approval for the "internet based learning" approach. Lets see how it works out.

Apart from this I talked to a bunch of final year students about carrying out their final year project with Mozilla and also about participation the upcoming design challenge. More about that in another post.

Mozilla Developer Network (MDN) survey -- My inputs

I just finished the MDN survey and here is what I said in that last box which was put there for the people like us to pen down our rants. ;-)

• Project documentation needs improvement. It has improved and is improving, but a lot still needs to be done specifically about the oldest lines of code.
• I hear from some of the core developers that there are lots of hacks which make the code not entirely predictable. These need to be removed and replaced by proper, reliable code. Again the cleaning is going on, am just saying that it is really important so that there is some sort of SLA based on which people can develop applications.
• Consolidation of the content on MDC and MozEdu so that we can have a "The Mozilla Book", which any beginner can go through and dive into Mozilla related development -- either the platform or the browser or the add-ons or anything.
• Finally, making various Mozilla components available in the form of easily pluggable library modules and step by step guides telling us how to use them.

I do not know if any of this is useful to anyone else in the community, but for me, these appeared to be very important based on my association with Moziila for about 2.5 years now.

Incrementally building Mozilla/Firefox

Mozilla code base is really huge and has variety of files which are built in a variety of ways. It was sort of always confusing for me to figure out where all I should run make after I change any of the files. I generally asked on the IRC and someone just told me where to run make.

Today it was the same thing. But I also thought I would as well learn the logic to decide for myself the next time. Here is the chat transcript of NeilAway answering these questions.

The MDC page (https://developer.mozilla.org/en/Incremental_Build) has almost the same content for the native code. Neil here explains it for all the types of files involved.

Also to add to the following things running : "make check" from the objdir will run the automated tests.

• For xul/js/css/xbl it usually suffices to find the jar.mn (it may be in an ancestor folder) and make realchrome in the corresponding objdir
• For idl you're often looking at a full rebuild, depending on how widely it's used
• For .cpp and .h you obviously have to make in the folder itself, and then look for a corresponding build folder
• Except for uriloader where you use docshell/build and content, dom, editor and view use layout/build
• If you're building libxul or static then this is all wrong
• You don't look for a build folder, I think for libxul you build in toolkit/library and for static you build in browser/app

Getting the size of an already loaded page (from cache) in a Firefox extension.

Today this question came up in the IRC (moznet, #extdev). One of the add-on developers wanted to get the size of the page, either bytes or number of characters. The most obvious thing that came to my mind was progress listeners for definitive answers or the content length from the channel for not so critical scenario. But then he said he wants it for an already loaded page. And he further said that the information is already there somewhere as it is shown by the Page Info dialog (Right Click on a web page and select View Page Info). He was indeed right. Somebody in the code is already going through the trouble of calculating the data size and we can just re-use that. And I immediately started the quest to find that out.

As usual to figure out any browser component I opened up DOM Inspector. That tool is improving, which was against my earlier perception (Sorry Shawn Wilsher), though the highlighting part is still screwed up. Nevertheless, locating that particular label "Size" and the textbox in front of it containing the value was not difficult at all. I got the "id" of the textbox containing the size value. (Its "sizetext" :) ).

Next it was MXR (http://mxr.moziila.org/) in action. I did a text search for the id and got a bunch of results, one of which was pageInfo.js with this entry : line 489 -- setItemValue("sizetext", sizeText); . It is here. The very line made it apparent that it is the place where the value is being set and hence it is the place from where I can get to know how the value is being calculated.

Once I saw the code it was very clear and straight forward and pretty simple also. We have the URL. From the URL we get the cache entry for that URL. (Every cache entry has a key and that key is the URL - so neat). We try to get the cache entry from the HTTP Session first and if that fails we try FTP Session. The cache entry has the size as an attribute on itself, so its just getting that attribute value. DONE.

I am not sure how this will behave if we have disabled every type of cache. AFAIK, there will still be some in-memory cache as long as the page is still loaded. Probably good enough.

That was the end of a small but interesting quest. :-)

Getting Open Source/Mozilla in my college - SJCE - Part I

Earlier I had written about my first Mozilla Education Status Call in which I mentioned my interest to bring Open source software in general and Mozilla in specific to my college, SJCE. Well, good news, it did not stop at that blog post. Actually speaking it had not started with that blog post either. It has been a long standing wish of mine, even from my college days when I participated in the Google Summer of Code 2007. (More about  it here). Back then there were a lot of short-comings, both from my side and the institution's side to actually make this idea into reality. Nevertheless, past is past and no point in brooding about it now. The good thing is that now both I and my institution have overcome our short-comings and we have started working towards making that idea into a reality.

Now for some background aka story telling (which I like the most :) )

As stated earlier nothing happened about this idea when I was in my college. Then after passing out of the college and having worked in the industry for about 12-18 months it hit me, very hard, that I did not learn a lot of things during my life as an engineering student which otherwise would have helped me a lot in my professional life. Also I learnt that I was not competent enough as an engineering graduate as compared to some of my foreign counterparts and also those from some of the "famed premier" engineering institutions of the country. It was not just one thing or two, but I saw differences in many aspects, both theoretical and practical. Gradually it occurred to me that these two aspects are inter-related. Since we did not have proper practical experience and exposure to real world software development we never really appreciated the basic theoretical concepts of computer science, which formed our regular syllabus. Note that here I am saying "we" and not "I". This part of the story talks about the state of most of my classmates and that is the worst part. Nevertheless, the moral of the story is the good old philosophy of teaching that the theory and practice should go hand in hand.

Now there is another part to this story. Before I start with it let me tell you that whatever I am putting here is based on what I have perceived. I may be wrong, but I personally don't think so. And this is absolutely not about boasting about myself. So the other part of the story is that, my association with Open Source development communities, Mozilla to be specific, has greatly helped me in my professional life. I am not going to give examples, but it has really really helped me a lot. Also it has sort of put me ahead of several other capable classmates and most juniors of mine (with the difference being considerably more in the case of juniors). The only differentiating factor between me and them was my exposure to developing a real world application, Mozilla Firefox, and the various lessons that I have learnt by being a part of the global developer community. I am also certain that I could have been a much better computer engineer if I had started working with Mozilla at a much earlier stage, say 2nd year or early 3rd year of engineering and had dedicated more time to it. I still continue to learn a lot of general computer science and software development concepts (concepts not specific to Mozilla development) even now whenever I try to fix a Mozilla bug or even when I try to answer any query on the IRC, many a times even when I just observe few people conversing on the IRC.

Ok, enough of story telling. Now is the part for moral of the story. Here is what I inferred from these experiences:

1) Engineering students, specifically Computer Science engineering students, must get exposure to real world engineering (aka application development) to understand and appreciate the theoretical concepts they learn.
2) Open source software development communities provide a suitable environment for students to work with real world applications. Suitable in terms of - opportunities, cost, mentoring and certainly a few more good things also.

With these two points, it was clear to me that we badly needed open source education/exposure for students in my college. I knew that once this happened the possibilities were endless. Every time I heard/read about some of the classic Free Software implementations done at Universities abroad, I thought that our college can at least have several continuous contributors to currently existing open source projects, if not have creators of some totally new world class software projects. We could be having several different groups of students working of different types of software which operate at various levels (which translates to contributing to different open source software). Then they all could be interacting to help each other in troubleshooting problems. I thought of scenarios/discussions like this happening in the hostel corridors:

Student_1 and Student_2 are working on the Mozilla Download Manager (and here goes the conversation)

Student_1 : Hey, I want to test my new implementation for Mozilla Download Manager for HTTPS downloads. I am unable to configure my test server for HTTPS. You got any idea?
Student_2 : No dude, never done any server side stuff. Lets ask Student_3 from the Apache team.

Then Student_3 comes and sets up Apache for HTTPS within minutes (because that's day-to-day kind of stuff for him) and Student_1 continues testing his new implementation.

After some time:

Student_1 : Oh man, SSL handshake is taking too much time. I need to talk to Student_4, he knows the SSL library code base.
Student_2 : Yeah, I talked about that to Student_4. He is coming up with a patch to reduce the handshake time. It will probably be ready by tomorrow, I guess. Apparently it was a race condition causing the delays.

And so on.

Something like this is really possible. In fact many things much bigger than this are possible. But only if our students start working with and for open source communities.

So this set of thoughts made me work towards getting Open Source into my college. Now that's the background and the story. In the next part I will write about the first set of steps taken towards this, how many of them worked and how many were dead even before they started. And just FYI, the next post too will have some story telling (Obviously since this is just a record of my experiences and my (our) actions).

Profiling (timing) the firefox build process

Its been nearly 2 years since I am building Mozilla Firefox myself on my machines - various machines of varying capacity.

Initially it was a desktop having Intel Pentium 4, Single Core (obviously), 2.6Ghz, 256MB RAM, running Slackware 11. It probably used to take about 1.5 to 2 hours (I do not remember it now). I never profiled that at that time. Getting a mozilla build itself was a big achievement for me.

After that it was another desktop having Intel Core 2 Duo, Dual Core (obviously, again), 2.4 GHz, 2GB RAM, running Windows XP. This generally took about 45 minutes. AFAI Remember, I had several other programs running when firefox was building.

And this discussion of amount of time taken to build firefox came up a few times in IRC and I myself had this wish to time the build process. Off late, that is from about last week this wish became very strong and today finally I did time it, that too on two machines, my laptop and my desktop. This blog post is the result of the these two profiling tasks. Here are the results.

Note: By profiling I did not do any complicated or intricate. I just used the "time" utility which tells how much time the command takes.

1) On my laptop. --- Build was the only application running apart from the services.
Specs:
IBM Thinkpad T60p. (The one which heats up a lot)
Intel Centrino Duo, T2600 @ 2.16GHz, (Dual Core)
2GB RAM
Windows XP Pro SP2.

The results shown by the "time" utility are:

real 36m33.476s
user 4m17.776s
sys 4m36.271s

The build was done in the MingW shell that the mozilla build system provides. I am not sure to what extent these are reliable, but the real time is pretty much acceptable.

Edit:

Today I ran the build command from the history and hence the 'time" prefix got in automatically and the build was timed again. Surprisingly today's times are way away from the last one. Here are the times:

real 74m26.484s
user 9m53.015s
sys 8m18.365s

Well this time a lot of other apps were running. Firefox (2 instances), Chatzilla, Outlook, Several command windows, Komodo Edit (which again is like another firefox), notepad and a couple of explorer windows. So the time being doubled is not a surprise. Guess this just gives a perspective. :)

2) On my desktop --- Apart from the build process, FF with Chatzilla was running and several instances of bash (Terminals) were running.
Specs:
DELL Optiplex 755 (Sleak, powerful, sometimes fragile)
Intel Core 2 Quad, Q6600 @ 2.4Ghz
4GB RAM
Ubuntu, Gutsy Gibbon

And the results are:

real 20m40.497s
user 19m4.320s
sys 1m17.885s


The two sets of times are a little confusing. But real is all that matters as that is how long I have to wait for the build to be ready.

If you are planning a build then this info might help you plan things accordingly.

Happy building.

Making firefox use a little lesser memory

A lot people tell me that firefox uses a lot of memory and it grows like anything when used for a long duration. From the discussions developers and some blog posts/forums it appears the prior to FF3 it was memory leaks which formed a major part of this. Apart from that one of the important features "bfcache - Back/Forward Cache" which, arguably, makes back and forward navigation very fast, uses a lot of memory. In on the pages I read apparently it can be up to 4MB per page. This cache essentially keeps the parsed HTML of the mark-up in the memory along with the Javascript state. Sometimes, or more like most of the times, this can very taxing. You might be the kind of person who does not really uses the Back-Forward navigation and in case you do it you are OK with a slight delay (which may not percievable with a good conenction). If indeed you are that kind then disabling this "bfcache" will probably make your firefox eat lesser memory.

The setting/preference that controls this behavior is : browser.sessionhistory.max_total_viewers

By default it is -1, which is no limit. Setting this to 0 (zero) will disable this cache completely. Essentially you are telling Firefox to not to store the state of any document in the memory. If you want to have this feature with a saner limit you can set it to an integer representing the number of pages you want to be saved in memory.

Like any other pref not exposed through the Options dialog this has to be edited by visiting the page about:config. Open this in a tab and key in (or copy and paste) the preference string. Double click it to edit.

May be you can now lose lesser hair as your other applications will run smoothly. :P

Hari Om.

My first Mozilla Education Status call

Mozilla is the only open source community which I have understood a little and also to which I have contributed a little. I always wanted to make my college a sort of Mozilla hub with several contributors and many feature developments happening out of my college. It actually started with an idea of a "Complete Open Source Hub", but it got reduced to just "Mozilla Hub" (either because of my laziness or because of lack of resources). Anyways I did not take any proactive steps towards that wish of mine, until recently when our college got the "Autonomous" status. That is when I realized that bringing open source software development in the course mainstream has become a lot easier as the power to form the syllabus and conduct the tests and examination rests with my college itself and not the University.

Just when I thought of doing something tangible, Mozilla came up with their "Mozilla in Education" program. This is a brilliant idea to drive open source into the student community and also give the students opportunities to work on real world applications. I was impressed by this program the very moment I read about it. I decided to present this idea to my HOD at the college and get him to start working offering Mozilla education to students in my college. I started reading more about it and today I also attended my first Mozilla Education status meeting conference call, which happens every week. I got a wealth of information.

This week we had Pascal F presenting to us about the "Design Challenge" program organized by the Mozilla Labs. He talked to us about the way in which they organized this program. It was all very inspiring. They had nearly 30-35 people from different parts of the world (literally). In this contest the students initially submitted mock-ups of their ideas, nearly 40 of them. Amongst those, 30 fully completed mock-ups were chosen for the second level, in which the students got mentoring by some the well known names in the Mozilla community. The mentoring consists of 10 Webinar sessions conducted using WebEx, over a period of 3 weeks. This is going on currently and will end at the end of this month. These mentoring sessions aim at converting those mock-ups into working prototypes. At the end, the best prototypes are given honors.

During the presentation Pascal mentioned some interesting things. Of the students from various countries, it was the students from so called "2nd World Countries" (like Romania, India, Argentina, etc.. ) who showed a lot more interest than their US counterparts. There was tremendous enthusiasm in them where as the students from US expected -- in his own words -- "being entertained" and "spoon-fed". Though this is an alarming thing when viewed from a global perspective, I was personally very happy that Indian students, my fellow country-men, have shown such dedication. Pascal also mentioned that they were so interested that they were up in the middle of the nights for the webinars. All in all, I am even more motivated to bring open source in general and mozilla in particular to my college.

I decided to take this program as an example and present it to my HOD this Saturday and try and make him accept this and similar programs as official ones and the projects done in such programs be considered for the completion of the course goals.

Thank you Pascal, thank you Mozilla. Lets hope to have a Mozilla India Center, at least an unofficial one at my college SJCE. :-)

An official full-fledged Firefox Add-ons dev guide

Having done a little work on Mozilla Firefox and extensions for it I have always felt the lack of an official, step by step document for extension development. I do accept that there are a lot of resources available on the internet. Innumerable number of blogs and tutorials explaining the process step by step. But most of them become outdated with newer versions of Firefox and the authors are not really keen about updating the info. That is why an official tutorial or guide from Mozilla itself would be the right thing. It will make sure the contents in the guide are up-to-date and worth reading for developing an extension for the currently available version of Firefox.

There are documents for extension development on MDC like the various links present at: https://developer.mozilla.org/en/Extensions but it was either scattered or pretty brief in most places though it did touch most parts of extension development. Nevertheless a wholesome "official" guide was needed and here it is now. I went through the guide and as the blog post says it is still in BETA with a lot of "TO-DO" tags in there. In spite of that it is very much usable. Do visit it and post back your feedback to make it a much better guide.

Add-ons Blog » Blog Archive » Firefox Add-ons Developer Guide (beta release) - Calling all Add-on Developers!

Lets hope we will have more and more quality extensions now. :-)

Browsers are undergoing continuous innovation.

It was sometime since I blogged about anything. I have had several things on mind and many of them are presents as drafts. But this one really caught my attention and I felt I should put in my thoughts about this.

Until a couple of years, people rarely looked beyond Internet Explorer for their browsing experience, though they kept cursing it a lot. After that came the Mozilla Firefox web browser with its pack of addons allowing users to actually customize for their needs. They could actually make the browser do what they wanted it to do and not just set some options. The browser wars had started again. At least I started reading about browsers and started following up on things happening with these browsers. Opera and Safari and a few other, actually used, browsers were not really "news" as such.
This was dying off. Firefox had created a sizable chunk of user base and was pretty stable with it. Except for few traditional enhancements like memory optimizations, bug fixes, etc.. nothing big was happening. It was a lot silent.

Then came the next wave with Google announcing the release of its browser with a nice, easy to understand "comic" book. It came with a whole new paradigm for building browsers with the "process-per-tab" concept. It was really innovative. Though discussions about this happened in other browser communities also, Google Chrome was the first one to implement it. Also it boasted of its super-fast V8 JavaScript Engine and also the browser UI, which gave more screen real estate to content than chrome. This was a real big thing and made the browser wave go much higher than what it had ever been. With the Google branding a vast majority of internet users rushed to have a sneak peak at Google Chrome or may be try it or even keep it as their regular browser. There was a lot of noise about this and people indeed listened. Mozilla and IE people were not silent and did responded very well. Mozilla came up with its ultra-fast "Tracemonkey" JS engine, implementing the trace trees and there by making it much faster than V8. IE8 also has the "process-per-tab" and "private browsing" features first presented by Chrome. But like any other sound this too dampened a little after it was created and browsers were back in the silent phase doing traditional improvements and bug fixes. At least that's how I percieved the situation.

[Edit 06-Mar-09 : Shawn Wilsher suggest that Tracemonkey had appeared before Chrome made the pubic appearance. He certainly knows these things better than me and I believe he is right. But still I wanted to keep my original post as it is and instead I put this separate edit note. :) ]

But I was clearly, totally wrong. People have realized that internet is the place to be in the future and thats where a large part of our life will be. With browser being the main and central interface for people to use that internet, it makes a real good sense to make this browser as robust and reliable as possible. New things keep coming on the internet, both and bad, the latter being more often, and the browser has to keep up with all of it. What we thought yesterday as being a good design apporach might just look senseless tomorrow. There just seems no end to it and researchers appear all ready for it. I am coming across so many innovations happening in the browser domain. This article : Researchers Say Gazelle Browser Offers Better Security -- Campus Technology -- gives us an idea about how much effort the scientists are putting in making our internet lives better. The article is about Gazelle, but it also mentions about another experimental browser OP.

This browser Gazelle, uses the Trident rendering engine (used by IE) but builds upon a OS based process architecture where websites form the processes and they communicate by passing messages like IPC (Inter-process communication).

I am not yet sure how this will all work out. Probably the websites need to built with some intelligence so that it can do the so called IPC when it actually has to. But the evoltion in browsers is for sure. They will not be same as they are now. Several things are going on along the UI front. When these things mature and come togther you can have the scenes of your favourite sci-fi movie scenes right in front of you everyday.

Lets just hope these come soon enough for people like me to enjoy, not when I am all grey hair and toothless.

Hari Om.

Image for a statusbar panel in a firefox extension

I was working on a firefox extension which, like many other extensions, was adding a small button to the status bar. Doing this is very clearly explained here in : this MDC tutorial

I followed the instructions properly but to my surprise I did not see the image on the status bar, but just a square box in the defualt chrome color. I tried forums/web search and the IRC too, but no help. Then I read the statusbarpanel reference page - statusbarpanel - MDC -- completely and it appears that for the image to show up the statusbarpanel has to be of a specific class called : "statusbarpanel-iconic". I just added that and it worked. :-)

Here is my code

<statusbar id="status-bar">
     <statusbarpanel id="graph_status_bar_panel"
              image="chrome://myext/skin/chart_status_bar.png"
              class="statusbarpanel-iconic" onclick="toggleGraphPanel(event)"
              tooltiptext="View Graph Panel" />
</statusbar>

Documentation appears by itself -- from the code.

Beautifully Documented Code at Toolness

I am slightly into web and web related development and as part of that I come across various JavaScript (JS) libraries which  claim to make my life a lot easier and many of them actually do that. But several times there is a big hurdle that I have to cross before actually things become easy. Its understanding how to use that library. This sometimes turns out to be a pain, often bigger than the one if I had done everything by myself without any external library.

This is probably all going to change. The lack of documentation might just vanish and all the necessary documentation might start appearing from the code itself. And the steps for building this, collating things and publishing on website are taken care of. You just need to annotate your code with the right tags and the JavaScript linked at the top (Written by Atul) will do the documentation generation and will also display it alongside code.

This is particularly useful for libraries providing various APIs as the users can see a function in the raw code and understand its meaning and purpose and the arguments it expects and its return value. All in once place at one time.

This is really cool. Go check out the tool and give the world a better library to use :-)

Happy (auto)Documenting

offline cache discussion with campd

[ 2:20 am] <brahmana> hi all,
[ 2:20 am] <brahmana> Looks like my earlier question about offline cache got lost here...
[ 2:21 am] <brahmana> I read the HTML 5 spec and understood that the cache will be versioned and hence multiple versions of the same cached element will be present on the client's disk. Is that so?
[ 2:22 am] <campd> yeah
[ 2:22 am] <campd> as of 3.1
[ 2:22 am] <campd> in 3.0, there's only one version
[ 2:23 am] <brahmana> ok..
[ 2:23 am] <campd> brahmana: though they won't stick around long
[ 2:23 am] <brahmana> ok..
[ 2:23 am] <campd> brahmana: when you visit a page, it'll download a new version. Once any page using he old version is navigated away from, it is cleaned up
[ 2:25 am] <brahmana> campd, So everytime the user goes online and visits a website which has offline cache, the cache is refreshed provided no page is using the old cache.
[ 2:26 am] <campd> brahmana: sorta
[ 2:26 am] <campd> brahmana: every time they visit an offline cached website
[ 2:26 am] <campd> brahmana: it will check for a new version of the cache manifest
[ 2:26 am] <brahmana> ok..
[ 2:27 am] <campd> brahmana: if there's a new manifest, a new version of the cache will be created and fetched
[ 2:27 am] <brahmana> campd, ok.. answers my question fully..
[ 2:27 am] <campd> cool
[ 2:27 am] <brahmana> campd, However I have another question..
[ 2:27 am] <campd> ok
[ 2:28 am] <brahmana> Now is this cache application specific? As in if a image with the same src is referenced by two websites, the image will be cached separately for each webapp?
[ 2:28 am] <campd> yes.
[ 2:29 am] <brahmana> ok..
[ 2:30 am] <brahmana> campd, Will this offline cache in anyway affect the regular browsing when the user is online?
[ 2:30 am] <campd> if they're online, browsing an offline app, it will be loaded from the cache first
[ 2:30 am] <campd> it won't affect online browsing of non-offline pages
[ 2:31 am] <brahmana> ok..
[ 2:31 am] <campd> so if http://www.foo.com/offline.html is an offline app that references http://www.bar.com/another.html
[ 2:31 am] <campd> going to http://www.bar.com/another.html will NOT load it from the offline cache
[ 2:31 am] <campd> but going to http://www.foo.com/offline.html WILL be loaded from the offline cache
[ 2:32 am] <brahmana> okay..
[ 2:33 am] <brahmana> campd, Regarding the local storage, Can it be looked at as an extended form of what currently is cookie?
[ 2:34 am] <campd> kinda, yeah
[ 2:34 am] <brahmana> Is there any limit on the amount of data that each web-app gets on this local storage?
[ 2:35 am] <campd> yep
[ 2:35 am] <brahmana> Because the spec says that the web-app can use this to store user created _documents_
[ 2:35 am] <campd> 5 megs for the etld+1
[ 2:35 am] <campd> if the domain has the offline-app permission it gets more, but I forget the exact number
[ 2:35 am] <mconnor> campd: is that right? I thought I remembered some wacky combination thing
[ 2:36 am] <brahmana> oh.. ok.. thats pretty big space..
[ 2:36 am] <campd> (which I assume is the wacky combination mconnor's referring to ;))
[ 2:36 am] <mconnor> no
[ 2:36 am] <mconnor> it was something like "foo.bar.com can have 3 MB, and bar.com can have 2 MB" or something
[ 2:36 am] <mconnor> in whatever combination
[ 2:37 am] <mconnor> maybe that was the spec that got deprecated?
[ 2:37 am] <campd> I think right now it's just "5 for the whole etld"
[ 2:37 am] <campd> err, etld+1

How libffi actually works?

I came across this libffi when I thought of working on js-ctypes. Though my contribution remained very close to nil, I got to know about this fantastic new thing libffi. But I did not understand how it actually worked when I first read. I just got a high overview and assumed that the library abstracts out several things that I need not worry about when making calls across different programming languages. I just followed the usage instructions and started looking at the js-ctypes code. That was sufficient to understand the js-ctypes code. But today when I was once again going through the README, I actually came across one line that made things a little more clearer. The first paragraph in "What is libffi?" tells it all. Its the calling conventions that this library exploits. I had written a post about calling conventions some time back. As mentioned in the readme file, its the calling convention whcih is the guiding light for the compiler. So when generating the binary code, thecompiler will assume will that the arguments that are being passed to that function will be available in some place and also it knows about a place where the return value will be kept, so that the code from the calling function will know where to look for it.

Now we know that the ultimate binary code that we get after compilation is the machine code. So it is basically a set of machine supported instructions. These instructions are certainly not as sophisticated as those available in the C - like the functions. So what do these functions transalte to? Nothing but a jump of IP(instruction pointer) to an address where the binary code of that function is. Inside this code, the arguments passed are accessed by referencing some memory location. During compilation the compiler will not know the precise memory locations (obviously). But the compiler has to put in some address there when generating the code. How does it decides on the memory location? This is where the calling conventions come into picture. The compiler follows these standard steps. Since its the compiler who is generating the code for both calling a function, where arguments are sent, and the code of the called function, where those args are received, the compiler will be knowing where it has put the arguments and hence generate code to use the data in those locations. From this point of view, the main(or is it the only one) condition for the binary code of a function to work properly is to have its arguments in the memory locations it thinks they are in and and the end place back the return value in the right location. And from what I have understood till now, it is this point that libffi exploits.

When we are forwarding calls from an interpreted language, like JS, to some binary code generated from a compiled language, like C, there are two things to be done:

0. As discussed earlier, whatever arguments are passed from JS are to be placed in the right locations and later take the return value and give it back to JS.
1. Type conversions -- The types used by JS are not understood by C. So someone should rise up to the occasion and map these JS types to their C counterparts and vice-versa.

The first of these is taken care by libffi. But the second one is very context specific and totally depends on the interpreted language. It does not make sense to just have a catalog of type convertors for every interpreted language on this earth. So these two steps were separated and spread out as two interacting layers between the binary code and the interpreted language code. libffi now takes care of the calling convention part and making sure the binary code runs and gives back the results. And the job of type conversion is the job of another layer which is specific to the interpreted language which wants to call into the binary code. And hence we have these different type converting layers for different interpreted languages: ctypes for python, js-ctypes for JS (and probably some more exist). Well with this renewed and clearer understanding I hope to actually contribute to js-ctypes.

Happy calling (with conventions) ;-)

Discussion with biesi, bz and gavin about channel and tabId in #developers

brahmana wonders if biesi was able to examine the UML diagrams

[ 8:24 pm] <biesi> brahmana, sorry not yet
[ 8:24 pm] <brahmana> thought so..
[ 8:24 pm] <brahmana> biesi, anyways another quick question.
[ 8:25 pm] <biesi> brahmana, yes?
[ 8:26 pm] <brahmana> biesi, Can you please have a look at this one: http://wiki.mozilla.org/images/a/a0/Brahmana_URI_Loading_DocShell_Code.jpg -- Which would be the ideal point in the sequence to associate the tabId to the channel created.
[ 8:26 pm] <brahmana> ?

[ 8:26 pm] <brahmana> biesi, I want to know where I will have access to both of them.
[ 8:27 pm] <timeless> brahmana: pretty

[ 8:27 pm] <biesi> brahmana, um

[ 8:28 pm] <biesi> brahmana, nothing in that diagram has access to both :-)
[ 8:28 pm] <brahmana> timeless, thank you.. more here: http://wiki.mozilla.org/User:Brahmana/Netwerk_Docs (just in case)

[ 8:29 pm] <brahmana> biesi, ok.. so how much prior to webBrowser will I have to go to get a tabID ?
[ 8:29 pm] <biesi> brahmana, tabbrowser.xml

[ 8:29 pm] <biesi> its loadURI function or something like that

[ 8:29 pm] <biesi> brahmana, of course some things call loadURI on the web navigation directly...

[ 8:29 pm] <brahmana> biesi, yeah.. thats how I created that sequence diagram..


[ 8:30 pm] <brahmana> biesi, Can't I get hold of the tabID in C++ ?
[ 8:30 pm] <biesi> C++ has no concept of "tab"
[ 8:31 pm] <brahmana> But the <browser> present in each tab corresponds to one nsIWebBrowser, isn't it?
[ 8:31 pm] <brahmana> <browser> == the xul browser element

[ 8:35 pm] <biesi> brahmana, no
[ 8:35 pm] <biesi> there is no nsIWebBrowser in firefox
[ 8:36 pm] <biesi> that's only used for embedding
[ 8:36 pm] <timeless> unfortunately we don't use the same apis everywhere :(
[ 8:37 pm] <brahmana> oh man..
[ 8:37 pm] <biesi> brahmana, there is one docshell per tab
[ 8:37 pm] <brahmana> then the starting of my sequence diagram is wrong..
[ 8:37 pm] <biesi> if that helps you
[ 8:37 pm] <brahmana> yeah.. I am aware of that..
[ 8:38 pm] <brahmana> and I thought it was nsWebBrowser that held a reference to a docShell and made calls on the docShell
[ 8:38 pm] <biesi> ah, no
[ 8:38 pm] <brahmana> But as it appears firefox does not use nsWebBrowser itself...
[ 8:38 pm] <biesi> the browser holds the docshell directly, I believe
[ 8:39 pm] <brahmana> you mean the xul browser ?
[ 8:39 pm] <biesi> yeah
[ 8:39 pm] <brahmana> What C++ object does that map to?
[ 8:39 pm] <brahmana> something under widgets?
[ 8:39 pm] <biesi> the xul browser?
[ 8:39 pm] <brahmana> yeah
[ 8:40 pm] <biesi> um
[ 8:40 pm] <biesi> some xul magic
[ 8:40 pm] <biesi> nsXULElement.cpp perhaps
[ 8:40 pm] <brahmana> oh.. let me see
[ 8:40 pm] <biesi> via the boxObject maybe?
[ 8:41 pm] <biesi> but note that the <browser> is mostly an XBL thingy
[ 8:41 pm] <brahmana> oh man.. this is getting heavily complex..
[ 8:41 pm] <timeless> it really is

[ 8:43 pm] <brahmana> Now the JS call: browser.loadURI() will be a call on the corresponding nsXULElement object, which actually holds a reference to the docShell. Is that right?
[ 8:45 pm] * brahmana requests to put aside the XPCOM stuff that happens in the above sequence..
[ 8:45 pm] <brahmana> sorry, the XPConnect stuff..
[ 8:46 pm] <gavin|> yes
[ 8:46 pm] <gavin|> though the nsXULElement isn't really involved
[ 8:46 pm] <gavin|> apart from being associated with the JS object that implements the XBL methods
[ 8:48 pm] <brahmana> gavin|, Can you please elaborate a little on your last statement..
[ 8:48 pm] <brahmana> ?
[ 8:49 pm] <brahmana> Or is there a doc that I can read up to orient myself a little before asking lots of questions here?
[ 8:49 pm] <gavin|> nsXULElement itself doesn't have anything to do with the XBL implemented methods
[ 8:50 pm] <gavin|> it's just a "container"
[ 8:51 pm] <gavin|> it's not really useful to say that you're interacting with a nsXULElement, because you're really interacting with an XBL bound node
[ 8:51 pm] <gavin|> and the XBL <browser> methods implemented in JS are what matters
[ 8:51 pm] <gavin|> not the nsXULElement class methods
[ 8:52 pm] <brahmana> oh.. ok. so the browser.loadURI() is (most probably) implemented in the JS itself. This JS object holds a reference to the docShell directly and thats how the calls are routed -- makes sense?
[ 8:53 pm] <gavin|> that's about right
[ 8:55 pm] <brahmana> now this XBL/JS implementation is present in tabbrowser.xml?
[ 8:56 pm] <gavin|> and browser.xml, yeah
[ 8:56 pm] <gavin|> the tabbrowser contains <browser>s

[ 8:57 pm] <brahmana> This is the one I should be looking at: http://mxr.mozilla.org/mozilla-central/source/toolkit/content/widgets/browser.xml , right?

[ 8:58 pm] <gavin|> yes


[ 9:04 pm] <brahmana> gavin|, ok.. i figured the exit point to docShell: http://mxr.mozilla.org/mozilla-central/source/toolkit/content/widgets/browser.xml#186 --
[ 9:04 pm] <brahmana> Now I want to get the tabId in which this browser object is, how would I achieve it?

[ 9:04 pm] <gavin|> brahmana: not sure what you mean by "tabId"
[ 9:05 pm] <brahmana> tabIndex, the index of the tab in the tabContainer
[ 9:05 pm] <gavin|> you have a reference to a <browser>, and want to find which tab it's in?
[ 9:06 pm] <brahmana> yes..
[ 9:06 pm] <brahmana> well actually I am inside the browser's definition itself..
[ 9:06 pm] <gavin|> I guess you you need to loop through tabs and compare against their .linkedBrowser
[ 9:06 pm] <gavin|> don't think there's a utility method to do that
[ 9:07 pm] <brahmana> ok.. let me see how I can accomplish that..
[ 9:08 pm] <brahmana> I am thinking this... for(i=0; i < this.parentNode.browsers.length; ++i) if(this.parentNode.browsers[i] == this) return i
[ 9:09 pm] <brahmana> that must work, isn't it?
[ 9:09 pm] <gavin|> probably
[ 9:09 pm] <gavin|> assuming this.parentNode is the tabbrowser
[ 9:09 pm] <brahmana> yeah.. I verified that..
[ 9:09 pm] <gavin|> though the "browsers" getter builds an array by looping through taqbs
[ 9:09 pm] <gavin|> so it would best be avoided
[ 9:09 pm] <gavin|> to avoid having to loop twice
[ 9:10 pm] <brahmana> oh.. instead we directly loop through the tabs..
[ 9:10 pm] <gavin|> yeah
[ 9:10 pm] <gavin|> http://mxr.mozilla.org/seamonkey/source/browser/base/content/tabbrowser.xml#1693

[ 9:11 pm] <brahmana> And if i change the XBL now, is there anything that I need to do during the build?
[ 9:11 pm] <gavin|> you just need to rebuild browser/
[ 9:11 pm] <gavin|> (or toolkit/ if you're touching browser.xml
[ 9:12 pm] <gavin|> why are you changing them, though?
[ 9:12 pm] <brahmana> ok.. thats great.. i can even go for a full build.. :-)

[ 9:12 pm] <brahmana> I want to associate every channel with the tab it is working for..


[ 9:14 pm] <gavin|> brahmana: is therea bug # for this?
[ 9:15 pm] <brahmana> gavin|, oh no.. there isn't.. I saw similar thing in Firebug, Cookie Manager and wanted to explore on that..
[ 9:15 pm] <brahmana> if by any means this is a desirable thing we can have a bug...

[ 9:24 pm] <brahmana> Is the code under xpfe/ still used?
[ 9:25 pm] <gavin|> some of it is
[ 9:25 pm] <brahmana> the window mediator?
[ 9:25 pm] <gavin|> yes

[ 9:26 pm] <brahmana> Along with the tabIndex I would also require some sort of window Id i guess, as tabIndices are not unique across browser windows, isn't it?
[ 9:26 pm] <gavin|> right
[ 9:27 pm] <bz> tabindices need not be unique within a single window either
[ 9:28 pm] <gavin|> er, why wouldn't they be?
[ 9:28 pm] <brahmana> oh.. well if we do not open and close stuff, they should be right?
[ 9:28 pm] <bz> because they're under the control of the page author?
[ 9:28 pm] <bz> And nothing prevents an HTML author from sticking tabindex="2" on every single node in the document
[ 9:28 pm] <gavin|> we're talking browser tabs
[ 9:28 pm] <bz> oh
[ 9:29 pm] <bz> nevermind, then


[ 9:31 pm] <brahmana> gavin|, And about the bug for the stuff I am asking, I assume this isn't really a desired feature, is it?

[ 9:31 pm] <gavin|> brahmana: I still don't really know what the feature is

[ 9:35 pm] <brahmana> gavin|, To observe requests for one tab in observerservice ... there is requirement for coupling tab index with the http channel....

[ 9:35 pm] <brahmana> And that is what I am trying to accomplish, associate the tabIndex with the channel..

[ 9:37 pm] <bz> brahmana: er.... you know the docshell involved in both places, right?


[ 9:39 pm] <brahmana> bz, yeah.. I was talking to gavin and others about the way browser interacts with docShell. But I did not fully understand your question.
[ 9:39 pm] <brahmana> browser as in the xul browser element.

[ 9:40 pm] <bz> brahmana: docshell is he guts of a browser
[ 9:40 pm] <bz> brahmana: the part that actually holds the web page, etc

[ 9:41 pm] <brahmana> bz, yeah.. that was evident from this one: http://www.mozilla.org/projects/embedding/docshell.html and also from the length of nsDocShell.cpp file..

[ 9:43 pm] <bz> ok
[ 9:43 pm] <bz> so you can get from a tab to a docshell
[ 9:43 pm] <bz> you can get from the channel to a docshell (usually)
[ 9:43 pm] <bz> then compare the two
[ 9:43 pm] <bz> for images you're out of luck
[ 9:45 pm] <biesi> brahmana, there can be a <browser> that's not part of a <tabbrowser>
[ 9:46 pm] <brahmana> bz, Whats special about the images?
[ 9:46 pm] <biesi> what's NOT special about images
[ 9:46 pm] <bz> brahmana: they don't so much follow necko rules
[ 9:46 pm] <brahmana> biesi, Are you referring to a situation with single tab?

[ 9:47 pm] <brahmana> bz, biesi yeah I had got the same statement when discussing about the request end notifications..
[ 9:47 pm] <biesi> brahmana, no, I'm referring to extensions or mailnews or whatever that doesn't support tabs
[ 9:47 pm] <brahmana> biesi, oh well.. that is probably not a problem. I don't think we would go beyond firefox.
[ 9:48 pm] <biesi> ok
[ 9:48 pm] <biesi> I have no idea what you're trying to do
[ 9:48 pm] * bz points to "extensions"
[ 9:48 pm] <bz> anyway
[ 9:48 pm] <biesi> I'm just saying, if you want to change browser.xml in mozilla.org
[ 9:48 pm] <biesi> 's repository, you can't assume that there's a tabbrowser
[ 9:49 pm] <brahmana> point fully accepted.. :-)
[ 9:50 pm] <brahmana> bz, I am not sure about getting to a docShell from a channel. Is there is straight forward way?
[ 9:51 pm] <brahmana> s/there is/there a

[ 9:54 pm] <brahmana> moreover the docShell will have reference only to one channel and I assume that is channel corresponding to the base document, i.e the main document request. Is that so?
[ 9:55 pm] <bz> brahmana: the docshell is the channel's loadgroup's notification callbacks
[ 9:55 pm] <bz> brahmana: generally
[ 9:55 pm] <bz> brahmana: we're talking about a channel having a reference to the docshell, not the other way around

[ 9:57 pm] <biesi> the load group has the channels/requests for all the loads
[ 9:57 pm] <biesi> except for iframes of course


[10:00 pm] <brahmana> biesi, bz.. a little out of the current discussion.. When the http-on-modify request is fired, will the connection be already set up? Is there a possibility to change the request URL in that event's listener?
[10:01 pm] <bz> "change" in what sense?
[10:01 pm] <biesi> the connection is not set up yet
[10:01 pm] <biesi> but you can't change the URL
[10:01 pm] * bz really wishes URIs were immutable and that channels' URI were readonly so people wouldn't ask questions like this
[10:01 pm] <biesi> the channel's URI IS readonly
[10:01 pm] <brahmana> ok.. :-)
[10:01 pm] <bz> ah, good

[10:01 pm] <bz> well, that URIs were immutable, then
[10:02 pm] <bz> I thought we were gonna do that for http sometime
[10:02 pm] <bz> flip the bit
[10:02 pm] * brahmana decides not to ask such questions to be compliant with bz's wishes..
[10:02 pm] <bz> (and see what breaks)
[10:02 pm] <biesi> oh we aren't? that sucks :/
[10:02 pm] <bz> well
[10:02 pm] <bz> we're not _yet_
[10:02 pm] <bz> I also wish URIs were immutable by default instead of the nsIMutable mess..
[10:02 pm] <bz> but then again, I could use a pony too


[10:02 pm] <bz> Or better yet, a kayak
[10:02 pm] <bz> it is?
[10:03 pm] * bz looks in his "to check in" folder
[10:03 pm] <biesi> there's so much stuff that I'd like to change if I could...

A web-wizard to create XPCOM components in JS

JavaScript XPCOM Component Wizard

As I might have mentioned in my earlier posts, creating XPCOM components can sometimes be hell. (So wait for js-ctypes to get on-board). Mozilla people know about this pain and hence have published sample code snippets to help you in figuring out what all is necessary and what all is optional. Even the process of creating your component from these snippets can be cumbersome sometimes. So one mozillian, ted, went a step ahead and created a web based wizard to create a component in JS. You just enter a few parameters and a skeletal component is ready for use. It simply saves a lot of time.
Just visit the link at the top and try your hands at it.

Happy Componenting. ;-)

--Brahmana.