My company is planning to implement a solution in multiple applications that will help to validate mailing addresses at the point of data entry. We're using UPS's Extended Address Validation (XAV) web service API to validate the addresses.
Our current plan is to build a .NET web service that can be used to communicate between our applications and the UPS API. We have applications in VB6, classic ASP, and .NET 2.0, so we'd like to implement a solution that can be easily consumed by each of these programming environments.
What are our (Microsoft) options for designing a web service that can be consumed by multiple clients? In particular, is there a way to design a single web service that can respond with JSON (in case we want to validate our web page using javascript) in addition to XML?
I'm new to designing web services and want to make sure we consider all of our options. I've heard terms like asmx, WCF, OData, etc., but I don't know which frameworks will support what we're trying to do and where to start.