Using XML with Legacy Business Applications

Default and Fixed Attributes

Ever had the experience of looking at the output of an application and not being able to figure out where certain data came from? Schema language carries over from DTDs the ability to define default Attributes for instance documents. Even if the Attribute doesn't appear in an instance document, a schema-aware XML processor will hand it over to your application when it processes the document. This feature may be of some use in scenarios where you are integrating in-house applications and have complete control over the environment. There are certainly differences of opinion, but many people don't find default values very friendly when exchanging data between organizations. We generally like to know explicitly what is ...