Add support for plugins

[jonbullock]

Add support for plugins for getting external content such as Twitter/Facebook and outputting it via the rendering pipeline.

[jonbullock]

Consider hook point for output as well so you could write a plugin to process output, e.g. CSS/JS minify.

[jonbullock]

Should allow tools like this to be used.... https://code.google.com/p/wro4j/

[jonbullock]

Consider JBoss Modules or Furnace from JBoss Forge?

[vietj]

imho you should keep it simple, at least for the moment.

In my various project I use java.util.ServiceLoader for discovering plugins, @PostConstruct for life cycle.

It is dead simple, comes with the standard JDK and works like a charm.

my 2 cents

[vietj]

btw, I am considering embedding JBake in one of my projects (http://juzuweb.org) to generate content at compilation time (using annotation processing) and would really appreciate if it remains simple to embed with just the jar it needs (specially if it uses plugins for decoupling the core from the additional features).

[jonbullock]

Thanks for the suggestion, I'll definitely look into that.

Excellent, I'd love to see JBake used in that way. If you need anything just let me know. I'll make sure this is a consideration when the requirements for plugin support are defined.

[rajmahendra]

I am working on this enhancement. For latest status please find https://github.com/rajmahendra/JBakeProject

[RainerW]

For an plugin architecture OSGi would be nice. Supports versioning, and with bndtools live reloading comes out of the box. But not sure if this suites the idea of an library anymore.

[jonbullock]

@RainerW Thanks for suggestion, plugin support is definitely on the roadmap but as you rightly mention what JBake is will have an affect on how support is implemented.

[mwanji]

+1 for @vietj 's ServiceLoader suggestion. It's a nice, simple way of doing things.

I was wondering how plugins would be integrated whrn JBake is used as an application. Would JARs be put in a plugins folder, and the contents of the folder be included in the classpath? How would plugins manage their dependencies?

[vietj]

ServiceLoader uses a ClassLoader for loading services, so it is a matter of the runtime that setup the ClassLoader to chose either a ClassLoader that load from the classpath or from another URLs with an URLClassLoader or another one. There are several ways to manage dependencies, in the case of CRaSH at the moment it is quite simple with a lookup in a shared plugin context, that has been working well until now (1.3 currently) because I don't have complex service dependencies, I expect this to become limited at some time and at this moment I plan to rework this with graph dependency management and somehow injection (both are trivial software), eventually I can spend time on this and contribute if it's needed.

[aalmiray]

+1 on @vietj's suggestion for ServiceLoader. I can suggest jipsy for keeping those service metafiles up to date.

@vietj: as an aside to your first comment, do you manually find and trigger @PostConstruct annotated methods or is there already a JDK utility that does that for you?