Offline Mapping Solution

I am in a need of a solution for mobile devices, which will allow to display offline map with some 400 POIS of a given city. I have digged a bit and am stacked with the idea. I will develop my application with rhomobile, so I would have browser, ruby . Could you maybe give some hint which library and tools should I use? It seems openstreetmap is what I need , but I don't understand or don't know which tool can do following

1) Expprt开发者_运维技巧 the whole city into offline file which then could be loaded by some javascript library from local folder and show

I have found out that with mapnik I can generate map tiles and offline in mobile app use them. Openlayers will serve as map showing framework. Thanks for them who tried to help.