How to make an offline map, but the data was online?

Question

Database

Hello, and a pleasant working day,
I ask you to take a little time.
in the regions, the speed of the Internet leaves much to be desired.
therefore, I ask you to give direction in which direction to look when creating an online and at the same time offline database map, where changes could be made online on it.
such a system is needed to monitor the country's water resources.
Thank you for your attention.

Answer 1

If we are talking about a browser application, then take leafletjs.com for maps (you can google a bunch of materials on how to pull data from OSM, Yandex, Google)
and to save data in the browser
https://github.com/mozilla/localForage
or
https:/ /github.com/tantaman/LargeLocalStorage

Answer 2

An offline application is distributed to places that does not require an Internet connection to work, stores data locally. Perhaps not all the data, but only for your region.
Once a day / week / month, the database is synchronized with the server

Answer 3

I will say something strange, unusual for web programmer lovers with these frontends of yours...
OziExplorer. Program. For. Windows.
Eats cards from hard. You can update them if you wish. GPS takes from anywhere, but it works without it.
It also eats files with POI - tags, displaying them on the map. Files can be pulled from the Internet (the sizes are scanty), you can only update.
It worked on my laptop with a cache of google maps or general staff from the Internet with a 300 MHz process and pulled these very points and own coordinates through the phone using the GPRS method, which was connected via IRDa.
I doubt very much that your Internet is worse than GPRS via IRDa.