The combination of data (including open data) with apps often represents cooperation between an app developer and a database or data set designer. They may be working jointly on a single project, but very frequently each is working on a component (data set or app) that will be paired with other components (app or data set) that have not yet been thought of.

There's an important question to ask at this point: who is doing this work? The answer to this question gets into the new world of app development.