If the exception is part of business logic and requires some non-trivial actions to handle it, the exception class should be made checked (inherited from Exception). Such exceptions are handled by the invoking code.

If the exception indicates an error and assumes interruption of execution and a simple action like displaying the error information to the user, its class should be unchecked (inherited from RuntimeException). Such exceptions are processed by special handler classes registered in the client blocks of the application.

If the exception is thrown and processed in the same block, its class should be declared in corresponding module. If the exception is thrown on Middleware and processed on the client tier, the exception class should be declared in the global module.