ETech 2005 Trip Report: The App is the API: Building and Surviving Remixable Applications

These are my notes on the The App is the API: Building and Surviving Remixable Applications by Mike Shaver. I believe I heard it announced that the original speaker couldn’t make it and the person who gave the talk was a stand in.

This was one of the 15 minute keynotes (aka high order bits). The talk was about Firefox and its extensibility model. Firefox has 3 main extensibility points; components, RDF data sources and XUL overlays.

Firefox components are similar to Microsoft’s COM components. A component has a contract id which an analogous to a GUID in the COM world. Components can be MIME type handlers, URL scheme handlers, XUL application extensions (e.g. mouse gestures) or inline plugins (similar to ActiveX). The Firefox team is championing a new plugin model that is similar to ActiveX which is expected to be supported by Opera and Safari as well. User defined components can override built in components by claiming their contract id in a process which seemed to be fragile but the speaker claimed has worked well so far.

Although RDF is predominantly used as a storage format by both Thunderbird and Firefox, the speaker gave the impression that this decision was a mistake. He repeatedly stated that graph based data model was hard for developers to wrap their minds around and that it was too complex for their needs. He also pointed out that whenever RDF was criticized by them, advocates of the technology [and the Semantic Web] would claim tha there were  future benefits that would be reaped from using RDF.

XUL overlays can be used to add toolbar buttons, tree widget columns and context menus to the Firefox user interface. They can also be used to create style changes in viewed pages as well. A popular XUL overlay is GreaseMonkey which the author showed could be used to add features to web sites such as persistent searches to GMail all using client side script. The speaker did warn that such overlays which applied style changes were inherently fragile since they depend on processing the HTML on the site which could change without warning if the site is redesigned. He also mentioned that it was unclear what the versioning model would be for such scripts once new versions of Firefox showed up.

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