About a month ago, I wrote a post introducing a HTTP Archive format that is used to export data from Firebug's Net panel.
Since that time we have made further progress and following info could be useful for all who are dealing with HTTP tracing logs and page load performance.
- NetExport - (requires Firebug 1.4a26 and higher) an extension that allows exporting HTTP tracing data from Firebug. This extension appends a new Export button into Firebug's Net panel toolbar (see the screenshot bellow).
- HTTP Archive Viewer - online tool that allows previewing of existing logs. The viewer uses the same visual style for visualizing HTTP tracing data as the Net panel. Note that it's possible to compare tracing info generated by multiple pages (which is also something what is planned for Firebug 1.5)
- HTTP Archive Format - description of the format for exported data (doc updated according to feedback we've got).
NetExport
HTTP Archive Viewer
A while ago, I have written a post about Firebug 1.2 activation that is used to enable and disable certain Firebug features and avoid performance penalties the user could pay when not using Firebug and just browsing with Firefox.
Since that time we have gathered a lot of feedback related to the activation model saying in short: it's too complicated, I don't understand how to use it. Even if it's not exciting to receive negative responses, thanks to all who took the time to explain what could be done better!
We worked hard to improve the activation. Kudos to John J. Barton who put a good deal of work into this and also thanks to Steve Souders for all his input.
So, read the rest of the post if you interested in how the activation model has been designed for Firebug 1.4.
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Since there is not much user documentation related to Firebug features (and there is a lot what to know about) I have decided to put together several posts about existing features.
This post is intended as a detailed explanation of the Net panel from the user perspective. This post is not about developing an extension for this panel or Firebug itself. Also notice that all features described below are available (some of them introduced) in Firebug 1.4.
You'll be surprised how many features is there! 
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One of the new features planned for future version of Firebug is export of all collected data within the Net panel (HTTP tracing info). This feature has been requested several times and it should be useful mainly for further analysis by other tools.
There is currently several existing tools that can be used for HTTP tracking. To name a few:
They have various advantages over each other. For example, in-browser tools can easily group requests by page and analyze browser-cache usage while network-level tools can easily gather low level detailed info (e.g. HTTP compression). But in general, they all can be used to track HTTP traffic.
It would be obviously very beneficial to have a common export/import format that is used across all HTTP tracing tools and perhaps other projects. This would allow effective processing and analyzing data coming from various sources.
I have put together a document (fist draft) that represents a proposal for HTTP Archive export/import format (based on HTTPWatch's structure, but designed for JSON). Any comments and suggestions are greatly appreciated!
Many thanks to Simon Perkins (HTTPWatch) who provides all necessary info.
A viewer for HTTP Archive data is available here.
A NetExport extension for exporting data from the Net panel is available here.
Thanks to Ashish Datta, Firebug is having a fresh new support for inspecting JSON in net responses. This feature allows to see JSON formatted as an expandable tree of items and also explore them using Firebug's Dom tab.
The view is available within Net panel and visible as soon as a JSON request is expanded. In such a case the user can see another tab (like Params, Headers, etc.). See the following screen-shot.
By clicking on links within the view (green labels) the user is automatically navigated to the Dom tab to explore particular parts of the JSON response as javascript objects.
The feature should be part of Firebug 1.4a11.
Ahshis is a senior at Tufts University and he did this work as a part of his class focusing on open source development. It's great to see how community around Firebug is growing and willing to contribute to this indispensable tool!
I've been recently working with John Resig on his great Firebug extension called Fireunit. This very promising extension is intended as an automated testing framework for Firefox extensions and it should also be useful for testing web pages in the future. It's still at the beginning, but growing and starting to be very useful for testing Firebug itself.
Such unit test framework is what I have been waiting for a long time. Not only debugging and profiling is important and the unit testing was the missing piece in the Firebug world.
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One of the new features introduced since Firebug 1.4a2 is possibility to extend Net panel with additional info. There are new APIs that allow to create a custom info-tab for network requests (like Headers, Params, etc.) from within a Firebug extensions.
This post is intended (a) to show how these APIs should be properly used by Firebug's extensions and also (b) to gather some feedback about the architecture.
So, let me know please, if there is something I haven't thought about when designing this new extension point.
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I wrote a post about my FBTrace Console extension a few months ago and as it turned out that the console is actually quite useful for exploring how Firebug works internally, it's part of the Firebug's code base now.
This new feature is integrated in Firebug 1.3X (still in alpha phase), where X means: the version with tracing enabled.
The primary purpose of the console is to display a list of tracing messages coming from Firebug as it runs. It's often tough to debug a debugger by another debugger and so, having the possibility to inspect logs is often really invaluable.
Notice that tracing-console is *not* the same as Firebug's Console panel. Console panel is intended to be used by web applications developers, while tracing console is for Firebug (or Firebug extension) developers.
So, move on if you want to see how it works...
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I have been waiting for a long time to write about this. Since Bug 430155 (new nsHttpChannel interface to allow examination of HTTP data before it is passed to the channel's creator) is now fixed, it's possible to intercept HTTP traffic from within a Firefox extension!
This fix should be part of Firefox 3.0.4.
This possibility is crucial for Firebug (and also Adblock Plus and Firekeeper can benefit from it) as one of its features is showing a response of any HTTP request made by a page. Until now, Firebug has been using Firefox cache and XHR monitoring to retrieve the response and display it to the user. While this worked quite fine for XHR (it's not that hard to monitor XHR responses) there was a big issue with monitoring all the other network requests. The most visible problem was probably submit of an HTTP form using POST method (known as double-load problem).
In some cases, the HTTP response isn't cached (and don't forget that Firefox cache can be disabled entirely) and Firebug had to fire a second request in order to get the response again and show it to the user. Of course, this was a big problem for every server that executed any (e.g. database) related actions (these have been executed twice). Uff...
Finally, I could implement new and reliable cache within Firebug 1.3 based on nsITraceableChannel. So, Firebug can use it anytime the response-source is needed without an additional request, e.g. if the user wants to see a network response in Firebug's Net panel...
Check it out, I am recommending latest Firebug 1.3 from SVN and till the Firefox 3.0.3 isn't available you can download latest trunk build from here. Any comments truly appreciated!
For those who are more interested, I have written an example that demonstrates how the nsITraceableChannel can be used.
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I have got quite a lot of valuable feedback since Firecookie 0.6 release and so, I have decided to create a fresh new version. Thanks to all who took their time and helped to improve this Firebug extension!
Download Firecookie 0.7 beta for testing here (0.7beta9). If you would find any problems please report it here. The extension should work with all versions of Firebug and Firefox.
If you are interested, read more about all new features (with bunch of screen-shots attached) or read release notes and see what bugs have been actually fixed.
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