Strawman: Services and service-providers support

[Bryan Atsatt]

While I agree that the service loader framework appears to be lacking
(very) important features, if it is going to be part of the SE APIs then
it seems reasonable to support it.

The ServiceLoader's polling model is OK as far as it goes, but I much
prefer the "activator" model, where a service module could announce the
availability of services during module initialization.

// Bryan

Glyn Normington wrote:
>
> *"Stanley M. Ho" <Stanley.Ho at SUN.COM>* wrote on 13/06/2007 07:19:10 PM:
>
>  > Since I have not heard any further input on the services and
>  > service-providers strawman, I suppose the EG is fine with the strawman
>  > overall except the issue raised by Richard. Unless I hear any objection,
>  > I will incorporate the appropriate portion of the strawman based on the
>  > feedback you have provided into the next revision of the specification.
>
> I am very concerned that the scope of JSR 277 is being expanded
> considerably without much attention being paid to the state of the art
> (particularly Spring-OSGi and Declarative Services). If we could
> implement good interoperation with JSR 291, we could delegate the
> complexities of supporting services to JSR 291 and technologies like
> Spring-OSGi that layer nicely on top of JSR 291.
>
> Apart from that, the support for services in the strawman has some
> obvious holes, so I don't think it is ready to be incorporated into the
> JSR 277 specification:
>
> 1. It seems to be lacking any form of dependency injection.
>
> 2. The namespace of services is global, but not partitioned by service
> interface version. The effect of this is that a module could import v1
> of a service interface class and obtain an instance of the service that
> implements v2 of the service interface and get a class cast exception.
>
> 3. There is no support for dynamic updates of service providers and
> notification of service updates to service consumers. (This is
> consistent with JSR 277's static nature, but I point it out as this is
> an obvious future requirement based on our experience in OSGi.)
>
> 4. There seems to be some confusion in the strawman between loading of
> service interfaces/implementations and construction and publication of
> service instances.
>
> I wonder what other Expert Group members think of this strawman. Silence
> does not necessarily indicate happiness, so it would be good to have
> more feedback.
>
> Glyn
>
>
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