My need is simple and commonly implemented in any location based app today, display to a user a list of all “things” in his/her area (or by a zip code / address)
Using Google Maps API (especially the new “store locator library“) sounds like the safest bet, but if I would like to develop something on my own, is there a “standard” way to do so? what are the options? Yahoo geo-location API (and reverse lookup)? (Google Maps API require to use their map, not just API) purchace ZIP code files? other 3rd party services? online? offline? what is the secret?
Hmm. Zip codes can be handled a number of ways, and it helps to get a general background on how they work: http://en.wikipedia.org/wiki/ZIP_code
I’d purchase a USPS database with GPS coordinates, and work from there. A simple SELECT SQL query, with a LIMIT or TOP 10 (or however many search results you’d like) when calculating the magnitude of the vector should work here.
It’s been a while, but the algorithm for vector calculation is fairly simple, and should be easy to implemented in SQL: http://www.netcomuk.co.uk/~jenolive/vect5.html