On Mon, Nov 15, 2010 at 4:31 PM, Rickard Öberg <[email protected]> wrote:
> I have committed a first version of availability support in services. You > can now ask ServiceReference's "isAvailable". The default is always "true". Ok. > If the service has a configuration that extends Enabled (that has a > Property<Boolean> enabled()), that will be checked. If the service then also > implements AvailableService.isAvailable(), that will also be checked for > more dynamic determination. Maybe called "interface Availability" instead, since AvailableService sounds like other services are Unavailable ;-) > There is also a service qualifier @Available that can be used for DI. > Example: > @Service @Optional @Available MyService service; > will only inject a service if it's currently available, otherwise null. And this happens once? What if one has @Service @Available ServiceReference<MyService> ref; ?? I assume the ref will not be null, even if the service is not available. A follow-up should possibly be that ServiceProvider (importedService) can make services available/un-available after the initial start-up, and finally I still would like to see a listener/notification of that be exposed somehow (maybe on the ServiceReference). Further, I assume that a NotAvailableException is also defined, as from you call isAvailable() until you make the call to the service, it may no longer be available... > I was initially considering replacing isActive with isAvailable, but > currently they are both there. Does it make sense to have isActive() in an > API, or is that maybe more SPI'ish functionality as it relates to the > underlying service rather than usage? I can't see the difference. Either I would view "not Active" as a sub case of "not Available", or there is a domain specific meaning to it, in which case it belong in the the domain code. But I am not having a strongly formed opinion at the moment. Cheers -- Niclas Hedhman, Software Developer http://www.qi4j.org - New Energy for Java I live here; http://tinyurl.com/2qq9er I work here; http://tinyurl.com/2ymelc I relax here; http://tinyurl.com/2cgsug _______________________________________________ qi4j-dev mailing list [email protected] http://lists.ops4j.org/mailman/listinfo/qi4j-dev
