Share service instance between multiple components

Question

Suppose you have 3 lazily loaded components, A, B, and C – this means they are not loaded eagerly, as soon as possible, but depending on some condition (e.g., a back-end response).

Is it possible to have them share the same instance of a service as long as any of them exist (i.e. are not destroyed)? After they've all been destroyed, and as soon as any one of them loads again, I'd like a new service instance to be created and shared among all the lazily loaded components, i.e. the whole process repeats.

I was thinking this could be done by restricting the service to a module. However, it appears modules, once loaded, are never unloaded, so the service instance continues to exist even after its declared components (A, B, and C) have been destroyed.

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_{The approach outlined in https://stackoverflow.com/a/61163053/9445073 circumvents the problem by creating a Master component that provides the service instance to its Slave components. This setup doesn't suit my needs for flexibility because my components A, B, and C could be located anywhere on the page.}

Answer 1

What you describe is against angular's lifecycles and I highly want to discourage you to try to change that.

I think you should think more about some "session" instance and a service, that handles those sessions. The components register themselfes on this service. If there is no sessionContext active and a registration happens, the service creates a new sessionContext. If a deregistration from a component happens and it was the last service registered, clear the session context.

The SessionContextService is provided in root and always available.