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Output of Amazon Web Services Change Without Notice

CTDATA has developed a number of unreleased programs that tap into Amazon Web Services. We use these programs to do price analysis on books in the Amazon catalog that we are considering buying.

Last week, one of our price anaylsis tools broke. Initially, we thought it had to do with XML interface performance problems that were reported by web services users on Friday. When the problem did not resolve itself, we did some testing and saw that price offers were suddenly being returned with currency symbols. These symbols were not present before.

The addition of currency to the offer prices might have been inferred from a developer chat that took place on March 5. This chat discussed the introduction of Amazon Web Services to Amazon.co.uk. This would necessitate the introduction of some means of designating the currency in which each offer price is expressed. But the problem is that we didn't discover the text of this chat until after we did some troubleshooting, and worked around the changes that Amazon made.

We are surprised that these sorts of changes are made without a great deal of notice from Amazon.com. How do they think developers are using these web services? Don't they realize that prepending a currency symbol changes the XML node from something that can be interpreted as a number to something that has to be manipulated before it can be converted into a number? Didn't they realize that would have an effect on applications that are already in use?

It's harder to justify the development of applications that use Amazon Web Services when changes like these take place silently. Caveat developer.

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