I don't actually have THE answer for you... but! You can look at the source code of the libraries and find out where they do it. I had to do that for my first mobile web application for some virtual events.
You can get the un-minified version of most of them and read through it.
I'd like to make a web service that allows to find the shortest path between bus stations with Dijkstra's algorithm, then the path will be displayed on a map. (I have a database that contains the coordinated stations) but I do not know "how to start": , I am really blocked for a week and i dont find any thing , i dont find a tutorials as this subject
( This web service will be used by my android application)
realy i need help
(i use eclipse)
thank you in advance