Background

I am trying to understand when I should be using bound services. It seems that I could use a repository instead in most cases.

I understand the value of a bound service to be:

1. Inter process communication
2. Synchronous behavior
3. Lifecycle adherence (the bound service, if not started using startService, terminates when it has no bindings, and instantiates when it is bound to)

However, it seems those things can be accomplished with a Hilt injected repository singleton.

My current example includes an unbound foreground service which is responsible for remote uploads of aggregated data and a UI that displays that data. Both components require authentication functionality.

Problem

To give the UI and foreground service access to authentication status and requests I could do two things:

1. Inject both with an AuthenticationRepository.
2. Create an AuthenticationService and have both components bind to it.

Option 1 feels cleaner and more understandable. Option 2 seems to have some value that I do not understand. They both offer synchrony, communication, and lifecycle adherence.

Question

What are the pros and cons of my solutions here? How can I better define the purpose of a bound service?

CodePudding user response：

I am trying to understand when I should be using bound services

Most developers will not need one. More specifically, use a bound service when:

• the component really needs to be a service for other reasons, and
• you want synchronous communications with that service

Nowadays, most of the time, this winds up being an IPC scenario, either between a core OS process and your app or between two processes within your app. So, for example, a TileService winds up being a bound service, because that is how Google defined the contract between the service and a core OS process.

IOW, if dependency inversion (Dagger/Hilt, Koin, etc.) will solve the problem, that probably is the better choice.

Bear in mind that wide use of DI is a relatively recent Android phenomenon (within the past 5 years), so older materials might put unwarranted emphasis on bound services.

Option 1 feels cleaner and more understandable

FWIW, I agree.