I would like to set up a mobile application to send SMS messages to nearby contacts. To make it simple, here are the steps in the process:

  1. The user opens the app and adds a point on the map.
  2. A script automatically returns the list of contacts within a radius of 10 km around the point.
  3. The user's smartphone sends an SMS (via SIM card) to each contact found.

The nomadic user may sometimes be out of reach of the 3G/4G network, so the data (rasters, location and number of contacts...) will have to be stored in the smartphone memory.

Which technology do you think should be used for offline use?

Radius selection

closed as primarily opinion-based by xunilk, whyzar, tinlyx, BERA, Vince Feb 19 '18 at 23:22

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

  • Wow interesting question... There is a geo component, but I think the main technology resides in non-geo tech, ie PHP and other scripts that can communicate to services that pick up changes in a database. I would think a postgresql/postgis back-end hooked up to something would be good for this... (I think the votes to 'close' are because of the mainly non-geo component to the solution... would be curious to know how this is done regardless!) – DPSSpatial Feb 19 '18 at 16:56