How can I learn about creating web services for a database that infopath doesn't natively support?

Article:		Getting Started with Microsoft InfoPath 2003
Subject:		How can I learn about creating web services for a database that infopath doesn't natively support?
Date:		2009-03-02 09:12:12
From:		larryvirden

As I have been reading around the net, I see that while Infopath can support interacting with Excel, Access, and SQL Server, it doesn't natively interact with other databases such as Oracle, etc. In the articles that I read, the suggestion is always to write your infopath to interact with a web service. I've not yet found an article or book that describes how best to create a web service that can then be used with infopath to perform this type of functionality. I was wondering if there were suggestions on best places to read about ways to develop such a thing.