Hi All,
The HK2 team (Tom Beerbower, John Wells, Mason Taube, Larry Feigen &
myself) went to asarch last week to
discuss about some of the changes to hk2 that we had been discussing for
a while. Some of the ideas were
initiated by Jerome & Jeff Trent.
While the HK2 team is yet to present the full set of changes to the
asarch (which we will do so in about a couple
of weeks from now), it was agreed that, to start with, GlassFish
modules should move away from using non
standard Classes like Habitat and use standards based annotations and
classes as specified by jsr 330
(javax.inject.Inject, javax.inject.Provider etc.). To quote Jerome:
"Classes like Habitat exposes too many APIs
available to the users that makes the hk2 evolution very difficult. "
Also some of the APIs are unclear (when to
use habitat.getComponent() versus habitat.getByType()
/habitat.getByContract() ).
So, the first step is to move away from Habitat (where ever
possible) and use jsr 330 interface and annotations.
In order to do this, the hk2 team will be making the following
changes to the GlassFish modules.
1. Move away from org.jvnet.hk2.annotations.Inject to javax.inject.Inject
1.1 We will convert @org.jvnet.hk2.annotations.Inject Foo foo
to @javax.inject.Inject
Foo foo;
1.2 We will convert
@org.jvnet.hk2.annotations.Inject(name="foo") Foo foo
to @javax.inject.Inject
@javax.inject.Named("foo")
Foo foo;
1.3 We will convert
@org.jvnet.hk2.annotations.Inject(optional=true) Foo foo
to @javax.inject.Inject
@org.jvnet.hk2.annotations.Optional
Foo foo;
1.3 We will convert
@org.jvnet.hk2.annotations.Inject(name="foo", option=true) Foo foo
to @javax.inject.Inject
@javax.inject.Named("foo")
@org.jvnet.hk2.annotations.Optional
Foo foo;
2. If we find that a class injects Habitat (or Services) and uses
habitat.getByContract(Foo.class) or
service.forContract(Foo.class).get(), then we will do the following:
2.1 Introduce a new injection:
@javax.inject.Inject
javax.inject.Provider<Foo> fooProvider;
and 2.2 replace the getBycontract() / forContract() calls with:
fooProvider.get();
3. If we find that a class
a) implements PostConstruct,
b) injects Habitat (or Services) and
c) uses habitat.getByContract(Foo.class) or
services.forContract(Foo.class).get()*in the postConstruct
method, *then we will do the following:
3.1 replace the getBycontract() / forConttract() calls with:
@javax.inject.Inject Foo foo;
3.2 Obviously, we will talk to the module owner to find out why
the injection was not made in the first place.
Note: *The Hk2 team will be making the above changes and will reach out
to the module owners to find out what tests (dev tests, QL etc.) need
to be run before committing the changes.*
Please let us know if you have any questions / concerns.
Thanks
Hk2 team