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Difference between revisions of "Equinox Summit 2007 Results"

(Component Programming Models)
(Component Programming Models)
Line 11: Line 11:
 
** Client is handed a proxy to the service object
 
** Client is handed a proxy to the service object
 
** Framework manages binding of a real service to the proxy dynamically
 
** Framework manages binding of a real service to the proxy dynamically
** Distinguish between mandatory service requirements
+
** Distinguish between mandatory and optional service requirements
 
*** Mandatory: your bundle isn't started until all the mandatory services are available
 
*** Mandatory: your bundle isn't started until all the mandatory services are available
 
*** This only guarantees availability at a moment in time: at the moment of startup all mandatory services are available, but they could disappear after that moment.
 
*** This only guarantees availability at a moment in time: at the moment of startup all mandatory services are available, but they could disappear after that moment.

Revision as of 14:27, 25 September 2007

The Equinox Summit 2007 was arranged as a set of lightning talks and a series of breakout sessions. Each session had a number of parallel discussions with self-assigned and self-organizing participants. The groups then reported to a plenary session, summarizing their results and possibly adding more topics to be discussed in further breakouts.

Day One Results

First breakout meeting

Component Programming Models

  • Service helper: ideal for one-time use.
  • Spring
    • Injection model - no code to acquire the service
    • Client is handed a proxy to the service object
    • Framework manages binding of a real service to the proxy dynamically
    • Distinguish between mandatory and optional service requirements
      • Mandatory: your bundle isn't started until all the mandatory services are available
      • This only guarantees availability at a moment in time: at the moment of startup all mandatory services are available, but they could disappear after that moment.
      • If a mandatory service goes away, the services exported by the bundle needing the service is unregistered.
    • For stateful services, there is a listener model - bind an unbind events occur as service implementations arrive and depart
    • It would be interesting to be able to declare a default service implementation that would be used whenever no real service is available
  • Requirements for Spring service support: Spring core, Spring AOP, a few other essential Spring core pieces
  • Service Application Toolkit: IBM toolkit for making it easier to work with OSGi services
  • How do we reconcile and combine the various component toolkits available: Spring, DS, SAT, extension registry
  • Spring initializes the app context asynchronously. Typical Eclipse programming model assumes that all initialization has completed by the time any classes are loaded in that bundle.
  • To be scalable, we need a model where service wiring is persisted across sessions, so we don't have the massive event storm of services being started and bound as the system comes up.
  • Most bundles are POJO - how do they specify that they need Spring or some other component system to be available at runtime? Ideally 95% of bundles don't know or care about the active component system - but they need some component system to be around at runtime to inject the services they need.
  • Can we come up with a common syntax where a bundle can specify its service and extension registry imports/exports, and be agnostic about the runtime that will parse it and provide the runtime capabilities.
  • Scoping: extension registry / services are global - how can I publish extensions/services that are only available in a particular scope* only particular set of bundles have access to it. In J2EE world, sometimes only want to register/bind services within a particular web app. Scoped registries - local versus global extension registry.

p2 Design Deep Dive

Tooling

Server Side

Second breakout meeting

Topic 1

Topic 2

Topic 3

Topic 4

Day Two Results

Third breakout meeting

Topic 1

Topic 2

Topic 3

Topic 4

Fourth breakout meeting

Topic 1

Topic 2

Topic 3

Topic 4

Fifth breakout meeting

Topic 1

Topic 2

Topic 3

Topic 4

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