Android tells system regarding how to manage
Android apps are built using four essential blocks: Activities, Services, Broadcast receivers, and content providers which are described as follows. · Activities: An activity is the interfacing window through which user can interact with the application such as performing the task, sending a message, and clicking the photo. It also keeps track of user’s current activity, his/her previous activities and gives priority accordingly. In addition, it provides a way to the apps to apply a user flow among each other and thus serving system for managing such flows.· Service: It is a starting point for any app which runs in the background and performs a required operation or any other task for remote access. There are two different semantics services: started service and bound service which tells system regarding how to manage the app. Started services can be playing a music in background or syncing of data in the background.
Here, music playback service is a known to the user via notification hence system gives it more resources in terms of keep running it. While in case of some background service which is not known to the users can be killed by system or get restarts later by the system in case of managing its process. Bound services are those which has been requested by some other app or the system itself. Example of the bound services is notification listeners, accessibility services, and live wallpapers.· Broadcast receivers: It is an android element which responds to system-wide declarations. For example, an app can give a scheduled alarm to broadcast receiver and can go off regardless of alarm’s status.
The broadcast can be made from the system or from the app such as data download, the battery is low, or a picture was taken.· Content Providers: It handles a common app data that one can store in file storage, on the web, SQLite or any other desirable location which can be accessed by the app. Further, through the content provider, other apps can request or alter that data if it has been allowed by the content provider. The content provider can similarly be spent for analysis and entering data which is only acknowledged to that application. 1.c The various permissions can be requested by an application which is as follows· Location: It grants the application to use user’s current location which can be used for desired app operation such as direction for the map, in fitness app and so on.
· Contacts: It allows to access contacts stored in the device which can be used for contacting the person from a different platform such as contact can be synced and use on social apps such as WhatsApp, Instagram and so on.· Camera: It gives permission to use device’s camera to click the photo or shoot video or any other task such as video call.· Storage: It sanctions storage access permit, it means that it can access the device content such as photo, video, documents and so on. · Microphone: It allows the usage of the microphone to the application through which it can record the audio or can be used for an audio call or similar tasks.