Re: [sisu-users] Sisu in OSGi

[gian.maria.romanato@xxxxxxxxxxxx]

First of all,

thank you very much for your detailed
answers.

> No worries, I'm working on updating the FAQ at the moment so this
is
> actually very timely :)

Good to know, I have a few more questions
:-)

> The example extender bundle uses
Sisu to scan bundles for components
> as they are started:
> 
>     https://github.com/eclipse/sisu.inject/blob/master/org.eclipse.
> sisu.inject.
> extender/src/org/eclipse/sisu/launch/internal/SisuActivator.java#L113

I had a look at the source code and
made some simple tests with a chain of two bundles, and everything worked
like magic :-)
If I understood correctly, the extender
instantiates multiple Provider<Injector> objects that will be all
registered into the DefaultBeanLocator. The additional registration in
the OSGi service using the extended bundle bundlecontext is only used to
perform proper removal from the DefaultBeanLocator when the owning bundle
goes offline. 

Not related to Sisu, but I noticed that
the SisuActivator uses a WeakReference to the DefaultBeanLocator. Is that
used for supporting a bundle update/refresh ?

>     *  extend dynamic updates to apply to injected
instances, not 
> just injected collections (https://bugs.eclipse.org/bugs/show_bug.
> cgi?id=386430)

The above bugzilla entry states that
injected lists and maps are already supported. Does it refer to Guice MultiBindings
(http://code.google.com/p/google-guice/wiki/Multibindings) or what ?
Also, when classes are found via scanning,
what happens when multiple implementations of the same interface exist?
Does Sisu automatically create a Guice multibinding ?

Does Sisu support Guice's chained linked
bindings (http://code.google.com/p/google-guice/wiki/LinkedBindings)? 
I am asking because my application comes
with default implementation of certain interfaces and base classes, but
we need a simple way of letting developers override them with custom implementations.
Ideally such overrides would be implemented in an extra OSGi bundle to
be included in the final application distribution. Would a simple Guice
module implemented in the extra bundle and declared in META-INF/services/com.google.inject.Module
work?

And now my last question, at least for
today :-). My application is using the OSGi extender pattern for collecting
metadata about classes included in its bundles. If I wanted our extender
to create a guice module on-the-fly to bind those classes, I believe I
could mimic the behaviour of the BundleInjector class that is included
in the Sisu extender. Is that right? I would need to refactor the Sisu
extender to make some code more reusable, and then have my extender create
additional BundleInjectors when appropriate. Would it be an issue for Sisu
if more than one BundleInjector exist for the same bundle?

Thanks in advance.
GianMaria Romanato.