Firefox Extension Developer Tips

Just a couple of tips for Firefox extension developers, hard earned after many hours of head scratching. Not adhering to either tips will confuse Firefox and XPCOM component will fail to load.

XPCOM components get loaded before chromes are loaded.

[Update: The most common problem related to this is Components.utils.import call fails during launch with NS_ERROR_FAILURE exception. To fix, wait until app-startup notification is received before importing javascript modules.]

This means anything defined in chrome.manifest won’t be available until “app-startup” event is observed. Note that Resource URI scheme “resource://” introduced in Firefox 3 uses resource directives in chrome.manifest which means you should defer Components.utils.import calls until “app-startup“.

XPCOM components implemented using Javascript should be defined as a pure object, not function.

So it should look something like this:

var MyServiceModule = {
  registerSelf: function(compMgr, fileSpec, location, type) {

Real-Time State of Mind

I need to get back to blogging more often. Having to type more than 140 characters feels wierd. 😉

Given that I’ll be attending TechCrunch’s Real-Time Stream CrunchUp this Friday, I thought a blog post on a key real-time stream problem would help me into a real-time state of mind.

Real-time streams have many technical problems to overcome many of which are thankfully being resolved by advances in technology and infrastructure but the problem that interests me the most is the user experience problems:

Information, real-time or otherwise, is meaningless if users are drowned within it.

Typical Twitter users see only a fraction of tweets from people they follow. The notion of Top Friends (related to my social radar diagram from 8 years ago) will help but at the cost of additional chores users have to do separate the greens from weeds.

The financial industry has used real-time streams for a long time so there is a lot to learn there technically. But, when it comes to user experience, they haven’t cracked the nut either, forcing traders to use bewildering number of charts and numbers on multiple displays and input devices to trade. So the emerging consumer real-time stream developers will have to break new grounds ourselves.