To answer the questions, follow these steps:
What architecture should we use?
You know and understand that there is more than one approach with which such a thing could be done.
Can we create this site using ASP.NET (should it)?
Could you. Similarly, you can do this as a Java servlet or PHP application. If you felt particularly perverse, you could probably get something to work in pure Javascript (but your clients may hate you)
TFL - google GPS
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