Just Because ...

Just because you can do something, doesn't mean you should.

Geeks like new things.  They like playing with new technology.  Using new tools.  Trying out stuff that they've never done before.  XML is a good example.  XML has a lot of really good useful purposes.  It allows for easier portability of data between disparate systems.  It is, for the most part, human readable.  It is good for configuration files.  Indeed, configuration files are probably one of the most commonly used applications for XML.

There is one thing (okay, probably more, but this topic needs to be short enough to keep your attention) that XML shouldn't be used for:  continuously updated reference tables or codes tables.  For instance, you wouldn't put the conversion rate between U.S. and Canadian dollars into an XML for processing by an application because it would involve daily updates to that file.  You probably wouldn't put the top 10 grossing movies of the week into an XML file either, as that changes quite often as well.  You could, however, put a list of provinces in XML as that normally doesn't change that often.

We have a carefully controlled production environment.  In order for any new files to be moved into Production we first deploy them to UAT, have them tested and then moved into Production.  You can see that by putting volatile data in an XML file you are creating a lot of extra work for you, the Deployment Team and even the users who need to test the changes as every change will create a lot of overhead.

What's the alternative?  A database.  Reference tables that have the potential to be changed on a frequent basis should never be put into XML files, they should be placed into a database with the proper screens in place to change the data.  Putting this sort of data does nothing for your application in terms of flexibility or ease of use.  It was a matter of using a cool new toy when it didn't need to be done.