I've developed a service that you can use to block the activation of a DS
component until a set of other services are ready. This is related to the
whiteboard pattern when the sender wants to be sure a certain set of whiteboard
services are present. Normally you can only assert the properties of 1 service
but this allows you to use a filter to select the aggregated properties of a
group of services. An example is when you need a set of at least 3 remote
services where there are at least 2 unique regions.
For example, you want to block until the average of the `foo` properties on the
registered Foo services is higher than 2:
@Reference( target="([avg]foo>=2)" )
ConditionalTarget<Foo> foos;
The Conditional Target object provides a direct reference to the services and
service references being tracked as well as the aggregated properties.
It is described in
https://github.com/aQute-os/biz.aQute.osgi.util/tree/master/biz.aQute.osgi.conditionaltarget
<https://github.com/aQute-os/biz.aQute.osgi.util/tree/master/biz.aQute.osgi.conditionaltarget>
And you can find the binary artifact in:
https://oss.sonatype.org/content/repositories/snapshots/biz/aQute/biz.aQute.osgi.conditionaltarget/
<https://oss.sonatype.org/content/repositories/snapshots/biz/aQute/biz.aQute.osgi.conditionaltarget/>
Feedback appreciated on the idea and execution. If people like this, I can
submit it to Apache Felix if they're interested.
Kind regards,
Peter Kriens_______________________________________________
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