2008/5/8 Richard S. Hall <[EMAIL PROTECTED]>: > Stuart McCulloch wrote: > > > 2008/5/8 Clement Escoffier <[EMAIL PROTECTED]>: > > > > > > > > > Hi, > > > > > > Creating instances like this have an inherent problem. You can't > > > assert > > > that > > > you're the only user of the created instances. > > > > > > > > > > > > that's not necessarily a problem - you may actually want global access > > :) > > > > but it's cool that iPOJO lets you scope the service visibility while > > allowing > > you to also open it up to the global service registry, if that's what > > you > > need > > > > > > Well, if the service is available for anyone to use, then the notion of > "having" your instance is essentially meaningless...particularly in the case > of a stateful service, as mentioned in the original message... >
but it's not necessarily an "inherent problem" if you're creating instances that don't have per-client state (there are other types of state) or you want multiple configurations that could be shared with other clients... certainly you should be aware that the service is going into the global service registry and as I already said the scoping in iPOJO is neat - but I prefer people to know there are these other options (and their pros/cons) > -> richard > > > > > > > > > Any consumers have access to > > > the service exposed by the new component instances (despite they don't > > > have > > > create the instance). > > > > > > In iPOJO, we provide a composition model doing this instantiation for > > > you > > > but asserting that only instances from the same composite have access > > > to > > > the > > > created instance. > > > For example, the following composition will create two instances from > > > the > > > specified factories. Services provided by these instances are only > > > available > > > for instances living in the composite. You could see composite as > > > another > > > service registry (in fact, it is exactly another service registry) > > > isolated > > > from the global (i.e. OSGi) service registry. > > > > > > <composite name="mycomposite"> > > > <instance component="your-factory-name"/> > > > <instance component="your-second-factory-name"/> > > > </composite> > > > <instance component="mycomposite"/> <!-- just to create an instance of > > > the > > > composition --> > > > > > > The specified factories (component attribute) can be in any other > > > bundles. > > > In fact, composites goes further and you can create composites like > > > this : > > > > > > <composite name="mysecondcomposite"> > > > <subservice action="instantiate" > > > specification="your_service_interface"/> > > > <subservice action="instantiate" > > > specification="your_second_service_interface"/> > > > </composite> > > > <instance component="mysecondcomposite"/> <!-- just to create an > > > instance > > > of > > > the composition --> > > > > > > In this case, the composite tracks service implementation (i.e. > > > component > > > factories) able to create instances providing the specified service > > > interfaces. > > > If these service implementations disappears or appears, the composite > > > will > > > deal with this dynamism by looking for new service implementation, > > > replace > > > the disposed instance... > > > > > > Of course, composites can import services from the global service > > > registry, > > > or can export services from the composite to OSGi. > > > > > > Clement > > > > > > > > > > > > -----Message d'origine----- > > > De : jaredmac [mailto:[EMAIL PROTECTED] > > > Envoyé : mardi 6 mai 2008 16:49 > > > À : [email protected] > > > Objet : Re: Are service implementors inherently singletons? > > > > > > > > > > > > Felix Meschberger-2 wrote: > > > > > > > > > > Not as per the OSGi framework specification. You might of course - > > > > as I > > > > said above - create a FooFactory and register that factory as a > > > > service. > > > > Your application would then get the FooFactory service and ask that > > > > FooFactory for Foo instances. > > > > > > > > Hope this helps. > > > > > > > > > > > > > > > Great, thank you - that does help. A FooFactory is exactly where I was > > > headed, and I wanted to make sure that I wasn't creating extra work > > > for > > > myself if there were some factory-like capabilities built in to OSGi. > > > > > > Thanks again, > > > Jared > > > -- > > > View this message in context: > > > > > > > > > http://www.nabble.com/Are-service-implementors-inherently-singletons--tp1709 > > > 0261p17092093.html< > > > http://www.nabble.com/Are-service-implementors-inherently-singletons--tp17090261p17092093.html > > > > > > > Sent from the Apache Felix - Users mailing list archive at Nabble.com. > > > > > > > > > --------------------------------------------------------------------- > > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > > For additional commands, e-mail: [EMAIL PROTECTED] > > > > > > > > > --------------------------------------------------------------------- > > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > > For additional commands, e-mail: [EMAIL PROTECTED] > > > > > > > > > > > > > > > > > > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > -- Cheers, Stuart
