On Apr 19, 2012, at 11:01 AM, Sergey Beryozkin wrote:
> On 17/04/12 16:37, Santiago Pericas-Geertsen wrote:
>>
>> On Apr 17, 2012, at 7:45 AM, Marek Potociar wrote:
>>
>>> There are 2 solutions that I've been thinking about:
>>>
>>> 1. introduce an injectable request-scoped ResourceContext with
>>> methods like inject(Class<?> subresourceClass), inject(Object
>>> subresource)
>>> 2. update the spec to mandate field injection on the sub-resource
>>> instances returned by sub-resource locator.
>>>
>>>
>>> So far I am leaning towards #1 as it seems more flexible.
>>>
>>> Any thoughts on the above?
>>
>> Why not both? As you say, (1) is more flexible but (2) is quite convenient.
>>
>
> I don't understand how the sub-resource injection can work at all.
> Lets take an example where a root resource is a singleton.
>
> This root resource can return sub-resource instances. Such instances can be created at a per-request basis or may've been pre-allocated and are singletons too. Only the root resource knows the rules.
Again, that's why I am leaning towards #1 as it is more flexible and lets the parent resource decide whether or not the injection should be used and how.
>
> How can the runtime make sure that the injection into sub-resources is thread-safe ?
It should not. It should be the responsibility of the parent resource.
Marek
>
> Thanks, Sergey
>> -- Santiago
>>
>>>> Hi,
>>>>
>>>> I would like to re-activate the already mentioned issue of lack of
>>>> support of DI in sub-resources.
>>>>
>>>> Usually you are going to separate JAX-RS resources and services into
>>>> separate classes. In that case services are going to be injected into
>>>> resource with @Inject (it works already fine in Java EE 6).
>>>>
>>>> However: usually JAX-RS runtime is navigating from the main Resource
>>>> to the sub-resource class via the @Path annotation.
>>>>
>>>> As developer you are creating a sub-resource using an ordinary "new"
>>>> and a constructor with parameters. The sub-resources instance is no
>>>> more managed and injection is not available.
>>>>
>>>> Proposal: we need a way to pass an instance to a JAX-RS runtime to
>>>> inject dependencies.
>>>>
>>>> Btw. parameterless constructors are not enough - usually you are
>>>> going to pass some context from the main resource to the sub resources.
>>>>
>>>> See also: https://java.net/jira/browse/JAX_RS_SPEC-72
>>>>
>>>> thanks,
>>>>
>>>> adam
>>>
>>
>
>
> --
> Sergey Beryozkin
>
> Talend Community Coders
> http://coders.talend.com/
>
> Blog: http://sberyozkin.blogspot.com