What are best practices for designing XML schemas? [closed]

Answer 1

One general (but important!) recommendation is never to store multiple logical pieces of data in a single node (be it a text node or an attribute node). Otherwise, you end up needing your own parsing logic on top of the XML parsing logic you normally get for free from your framework.

So in your coordinate example, <coordinate x="0" y="1" /> and <coordinate> <x>0</x> <y>1</y> </coordinate> are both reasonable to me.

But <coordinate> 0,1 </coordinate> isn’t very good, because it’s storing two logical pieces of data (the X-coordinate and the Y-coordinate) in a single XML node—forcing the consumer to parse the data outside of their XML parser. And while splitting a string by a comma is pretty simple, there are still some ambiguities like what happens if there's an extra comma at the end.

Answer 2

In our Java-projects we are often using JAXB to automatically parse XML and transform it into an object structure. I guess for other languagues you'll have something similar. A suitable generator can create automatically the object structure in your chosen programming language. This makes processing of XML often much easier, while still having a portable XML representation for the communication between systems.

If you do use such an automatic mapping, you will find this constrains the schema much - <coordinate> <x> 0 </x> <y> 1 </y> </coordinate> is the way to go unless you want to do special magic in the translation. You will end up with a Class Coordinate with two attributes x and y with the appropriate type as declared in the schema.