DataSnap - the creation of multi-platform applications. Its history is long enough, since very early versions of Delphi. The role and significance of this technology / platform changed during the evolution of Delphi / C ++ Builder / RAD Studio, but now there are a number of obvious benefits from its use in the context of mobile development.
DataSnap for creating a "backend" for mobile applications in the enterprise. Simply put, creating the first mobile Android / iOS app, you will want to ensure that it is "the outer world", not a "have completely outside" services (for this, it is likely suitable RESTClientLibrary here , though, and about C ++ Builder, but you can also here ). Its same connection (desktop) applications for the majority of "delfistov" means work in client / server mode. To work in client / server mode is useful to use ligaments FireDAC + InterBase ( explanatory video , there, however, first a review of the competition - so casually turned, and already about client-server - starting from the 12th minute . There's about iPhone and C + + Builder, but it works 100% for Delphi and Android).
External web-REST service requires a minimum of once per se. You can write himself, who has sufficient competence in this matter. You can try to do all the "classic" through a client-server. Client-server as a data transmission technology from the mobile client to the database server immediately grips the developer within certain limits. Above all, it - entering data into the database via SQL-query. But to a first approximation, you just want to, dear, kind and available - press the button on a mobile application, and see the "refinement" in the application running on the desktop. Let's do it.