Hi, Am Dienstag, den 06.05.2008, 12:14 -0700 schrieb jaredmac: > Is it true that each component in declarative services is inherently a > singleton? That is to say, if I have something like this: > > <component name="foo" immediate="true"> > <implementation class="com.pkg.internal.FooImpl"/> > <service> > <provide interface="com.pkg.api.Foo"/> > </service> > </component> > > then there will only ever be one instance of FooImpl?
For this exact declaration, there will only be a single instance created (and registered as a service) when the containing bundle is started. When the containing bundle is stopped, the service is unregistered and the instance dropped. When the bundle is started again, a new instance is created and registered as a service. So, it is actually more precise to say, that at any moment in time, there is only a single instance of the component existing, which is also registered as Foo service. > My use case is that I > want the application client to be able to say to Felix: give me a new > instance of all implementors of "Foo". In my case, Foo implementations have > state, and the application doesn't want to reuse an existing Foo. What you want is probably a Foo factory: Your application asks the Foo factory for instances of the Foo interface implementations. > > I know that I can get multiple implementors of an interface from one bundle > to another by doing this: > > <component name="foo-consumer"> > ... > <reference name="contributor" > interface="com.pkg.api.Foo" > bind="addFoo" > unbind="removeFoo" > cardinality="0..n" > policy="dynamic" /> > </component> > > but that will give me a list each of the Foo implementors, where again each > one is instantiated only one. Yes, the reference element just instructs the Declarative Services runtime to provide registered services to the foo-consumer. This is exactly the same as accessing these services through the BundleContext. > > I guess my question could be rephrased as: can an OSGi client request that a > new instance of a particular service provider be created, as opposed to > getting the existing instance? 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. Regards Felix --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
