Why to use Android Bound Service?

Question

I am curious to know why would you use Bound Service for 2 way interaction between Activity and Service when you can do the same kind of interaction with Started Service using local broadcasts and receivers defined in both Activity and Service

It will be helpful to know the pros and cons of each implementation.

I couldn't find any clear answer to this anywhere.

Answer 1

Using a bound Service is much more flexible. You can define methods on the Service (using AIDL) that return immediate results (synchronously), which you cannot do using LocalBroadcastManager. Using LocalBroadcastManager requires that you use your Service in a completely asynchronous way. This decouples the initiation of a service action with the return of the results (callback) which can make your code more complicated and more difficult to understand. Asynchronous use has some benefits, and there are places where you should use it, but if you have a bound Service you can choose exactly when to use synchronous calls and when to use asynchronous callbacks.

Also, the use of AIDL allows you to exactly describe the signatures of the services's method calls. If you use startService(Intent), you cannot guarantee that the caller will provide the correct arguments in the passed Intent, so you need to rely on the caller to "do the right thing" and/or you need to add a lot of additional argument verification.

Don't forget the comment from @CommonsWare about how LocalBroadcastManager only works if the Service is running in the same OS process as the rest of your app (which makes it unsuitable for programming things like system services, which are not running in your OS process).

Answer 2

A service is a component that runs in the background. It works to perform long-running operations without needing to interact with the user For example, a service might retrieve data over the network without stopping or blocking user interaction with an activity of an app or user may play music in the background while the user is in a different application. A service can be of two types or states:

Started: Once started, a service can run in the background indefinitely, even if the component which is started, is destroyed. A service is started when an app module or component, such as an activity, starts it by calling startService(). For example, retrieving contacts from phone book using service when Splash Screen starts.

Bound: A bound service offers a client-server interface that allows components to interact with the service, get results, send requests and even do so across processes with interprocess communication (IPC). A bound service is bound, when an app component binds to it by calling bindService().