Version 2 (modified by Dimitri Glazkov, 12 years ago) (diff)


Component Model (aka XBL2) Use Cases

A canonical set of uses cases that represents the set of problems we are trying to solve by implementing a component model. For implementation details, see XBL2 Spec.

Built-in HTML Elements and Their Behaviors


  • provide a uniform way to browsers to implement complex HTML elements, such as video/audio, sliders, progress elements, etc. possibly using scripting.
  • provide light-weight implementations of specialized markup languages


  • UA-level attachment
  • Ability to completely hide implementation from consumer
  • Restricted post-UA-level styling using pseudoclasses
  • High performance

Don't care:

  • mutable templates
  • dynamic attachment/detachment
  • template inheritance
  • attachment using CSS or DOM
  • content element (output ports), since they can't have children (this may change)

Custom User Interface Widget System

Build a widget system that allows the following:

  • asynchronously instantiate and initialize widgets
  • for instance, display a widget without starting up a script context, then progressively enhance with script.
  • seamlessly reuse widget written using various libraries or frameworks
  • use widgets declaratively, with minimal knowledge of the underlying implementation
  • provide a uniform way (i.e. DOM) to declare widget APIs

Layout Manager

  • make easier the restructuring of content to accommodate layout, both in an imperative and a declarative way
  • enable development of templating/theming frameworks