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I have an osgi implementation bundle containing an @Component which gets a @Reference to a service implementation.

There are multiple bundles which implement the service in different ways. No problem osgi picks one (using ranking or something similar). The problem is that the developer (I) make the decision about which service implementation to use.

But is it possible somehow specify at runtime (when the bundles start or at another time) which service implementation the @Reference annotation should select?

I suspect i can use ServiceTracker to do this.

[edit] just after i posted i found https://stackoverflow.com/a/5804265/7820234 (strategy pattern), which looks promising, the only thing is that i don't know which OperatorProvider services are available. I can implement the "selector service" and implement a ServiceTracker to manage the OperatorProvider services.

[edit2] Another way seems to be https://stackoverflow.com/a/32813211/7820234 with ConfigurationAdmin you seem to be able to change "myService.target". Extending or implementing this specific functionality of ConfigurationAdmin should do the job.

Which is the preferred way to go or are there maybe better options?

Community
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Okwan Tegls
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1 Answers1

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There is a simple solution you can try. Every DS component can be attached to a config admin pid. Using this config you can override the service filter for the @Reference.

If you for example have @Reference myService; then you can set the config property "myService.target=(color=blue).

This would then limit the reference to a service with the service property color=blue.

Christian Schneider
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  • Cheers @Christian, that sounds like the way to go. I will try to implement your solution tomorrow. – Okwan Tegls Apr 28 '17 at 20:04
  • Didn't have too much time this weekend, it was nice weather. But please note that it is "myService.target" instead of "target.myService". Took me a little while to figure out. But it works, although even my @ Reference is dynamic is still goes through the @ Deactivate and @ Activate cycle, need to do a bit more research if that is normal. – Okwan Tegls May 01 '17 at 11:52
  • You can make it dynamic by making it a volatile field. You might want to take a look here: http://enroute.osgi.org/services/org.osgi.service.component.html – Peter Kriens May 01 '17 at 12:12