My public component just disappeared!

You may notice that in certain situations, a public component on your plugin disappeared. This is because, under the covers, your public component is actually a Spring bean, registered as an OSGi service via Spring Dynamic Modules. Spring DM, by default, will automatically unregister a service if one of its dependencies goes away.

For example, say you registered a DictionaryService as a public component, and it depended on a MessageService. If the MessageService, for whatever reason, is unregistered, the Dictionary Service will be unregistered automatically. The only way to detect this is to turn on trace logging for org.springframework.osgi.service.dependency.internal and you will see something like:

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Exporter [dictionaryService] stopped; transitive OSGi dependency [messageService] is unsatifised

This can also happen if there is a circular dependency between two plugins that consume each others services.