User-designed background tasks in App inventor

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (page 70).In this thesis, I describe how I designed and built multiple components and extensions to App Inventor 2 that will allow application builders to create custom services and background tasks and to build applications that can interact with these services and tasks. Previously, the App Inventor platform only supported the creation of applications which had a screen in the foreground at all times. As such, the main abstraction of App Inventor was this notion of a "Screen". These screens could launch certain tasks to run in the background, but they were limited to the few tasks that were exposed by the App Inventor interface. Application builders could not design and customize their own background tasks. This restricted App Inventor users from building certain types of applications, for example, a music player application or an application that has heavy network communication. To enable users to build such applications, I extended the App Inventor platform to expose a "Task" object in addition to the existing "Screen" object. I created a messaging system which would allow Screens and Tasks to communicate with each other. I also developed additional task components that could be contained in these new Task objects. Users can customize the functionality of Tasks by putting together multiple task components. In this way, App Inventor users can now build more functional applications and explore a part of the Android SDK that was previously out of reach.by Vedha Sayyaparaju.M. Eng