An application can include various other applications. An included application has its own application directory and .app file, but it is started like part of the supervisor tree of another application.
- An application can just only be included by one other application.
- An included application can comprise other applications.
- An application that is not included by any other application is known as a primary application.
The application controller will automatically load any type of included applications when loading a primary application, but not start them. In place of, the top supervisor of the included application must be started by a supervisor in the including application. This means that while running, an included application is in fact part of the primary application and a process in an included application will consider itself belonging to the primary application.