While I agree with Peter and Hal, I think the heart of your problem is the mismatch between the preferred lifecycles of bundles in Eclipse environment vs the services-based approach.
In Eclipse (both the SDK and RCP apps), activation of bundles is done as late as possible. Lazy activation helps to ensure that Eclipse starts quickly, and code implementing things like views and buttons is only loaded when the user actually shows an interest in those things, e.g. by clicking the button. The whole Eclipse extension registry is set up to enable this by examining bundles when they are in the RESOLVED state. Services traditionally have a different lifecycle: they are offered up by a bundle before it knows whether any other component (or the user) actually wants them! So the bundle needs to be "eagerly" activated... but Eclipse strongly discourages this practice because bundle activation has an up-front cost. I believe the solution is to use Declarative Services. In DS, services can be registered in the service registry before the actual implementation object for the service is instantiated -- in fact, this is the default behaviour. A bundle offering services via DS still need to be activated, but now the activation is "free" because a classloader does not need to be created for the bundle until the service is actually used. To make this work in an Eclipse RCP environment, there are two possible approaches. First, explicitly name the bundles offering services in config.ini, and add the @start modifier. If you do not know in advance the names of the bundles then you could have an extender bundle which automatically starts any bundle with a Service-Component header. Regards, Neil On Thu, Apr 30, 2009 at 8:46 AM, Eugen Reiswich <[email protected]> wrote: > Hi OSGi-devs, > I have the following problem with osgi services. We develop basically > applications where dynamic is not an issue. So what I would like to make > sure in my application is that all services are registred properly at start > up - if not, the application will be shut down. In addition to that I want > to reuse my bundles in RCP applications so any concept must also be > applicable for RCP applications. > Say I have two bundles: > 1. org.mycompany.service (contains a service interface) > 2. org.mycompany.serviceimpl (contains the service implementation and > registers withing his activator an osgi-service) > What we do within the service bundle is this: > public void start(BundleContext context) throws Exception { > Bundle[] bundles = context.getBundles(); > // find the implementation for the service bundle > for (Bundle bundle : bundles) { > if ("org.mycompany.serviceimpl".equals(bundle.getSymbolicName())) { > // service impl found > if (bundle.getState() != Bundle.ACTIVE) { > bundle.start(); > } > } > } > // check if servicimpl has registred service properly > ServiceReference serviceReference = context > .getServiceReference(IMyService.class.getName()); > if (serviceReference == null) { > // shut down application > } > ... > > > From my point of view this is pretty error prone and difficult to maintain. > Is there a best practice approach how I can make sure that all services are > registered properly at start up of my application? How can I start my > serviceimpl bundles in RCP application as no one depends on this bundle > which is why the are never started? > We have spend now a lot of time to find solutions for this problem but they > all seem to be improvable. > Regards, > Eugen > _______________________________________________ > OSGi Developer Mail List > [email protected] > https://mail.osgi.org/mailman/listinfo/osgi-dev > _______________________________________________ OSGi Developer Mail List [email protected] https://mail.osgi.org/mailman/listinfo/osgi-dev
