Extensibility with Mark Finkle

Today's class was a presentation with Mark Finkle from Mozilla Corp. These are my notes.

Started off in proprietary software
Has only been with Mozilla for a year
The joy of extensions
- Primary way to get involved is through add-ons (extensions)
- Plug-ins killed the web (according to some) and are kind of discouraged
- Any app that uses the mozilla platform can be enabled to use extensions
- There's built in support in the UI, cross platform, platform APIs

Sometime people put their content in a .jar and then in the .xpi necessary for installation. Mark doesn't not advocate for this method because it can make things more confusing to new developers than need be.

He suggests keeping things as simple as you possibly can. Don't use jar files, multiple levels, keep manifests simple. Don't mimic other extensions that are often written by more experienced programmers.

Ted (:luser) has created a xul editor that can generate the skeleton for you, and if you use this then you have everything you need - just add content.

Use the pages on the MDC about the boilerplate aspects of creating extensions.

Stressed the importance of using the id of the rid firefox element to add your customized elements. Otherwise they may show up as document.getElementByID but they will not in fact appear. They will be in the ether until you merge them properly with the id. Examples are vbox id="appcontent" or statusbar id="status-bar". Not merging properly is 90% of what people get stuck on when working on the UI elements of their application and it's often that they are not using the id properly, don't have the proper id or a syntax error.

Best Slide: "Mozilla is like an Onion: It makes you cry, it smells, it has layers"

Mozilla's Tech Layers (1. XUL/JS/CSS, 2. XBL, 3. XPCOM)

Talking about layers he tells us that the top layer (the UI) is the easiest to get involved with and make changes to, but it's also the least documented and has no API. Whereas the XPCOM layer is clean and documented and has APIs so in some ways it's great to work with because it's designed to be extensible.

A demo follows about trying to dig into the code via DOM inspector.

Google searching hint - put MDC in the search criteria to help narrow the results.

Highlighting of the Code Snippets section in MDC which can really help point you in the right direction.

Thanks for coming and talking with us Mark. I look forward to working on extensions in the future.