Question

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XML attribute vs XML element

I’m creating an XML document that holds cinemas. I need a way to represent the facilities a certain cinema has, but am uncertain on how to structure it.

Should I have each facility as a node? And the text inside that node would either be a 1 or 0 (true of false)? Or would it be better to have each facility as an attribute or a “facilities” node?

Attributes:

<cinema id="1">
    ...
    <facilities advance_screenings="1" concessions="0" ... >1<facilities>
</cinema>

Nodes:

<facilities>
    <advance_screenings>1</advance_screenings>
    <audio_description>1</audio_description>
    <bar>1</bar>
    <concessions>1</concessions>
    ...
</facilities>

Thanks.

Answer 1

This is largely a matter of preference/style.

However – there are some rules of thumb:

• Non-primitive types must be elements (you are using the term “node”). You can’t have an attribute which represents a complex type – although you can do some pattern matching.

• 1000 attributes on a single element is probably not a great design – strive for human readability.

• As a corollary to the above point, avoid 1000 elements as direct descendants of a single element. (Nest/group elements in a logical structure).

Having some feeling for what a “nice structure” is vs. a “bad structure” is a complicated judgement which takes a lot of factors into account – such as the industry/context in which the data is being used, and what it represents. It’s similar to class design or probably closer to database design. Sometimes a hack job won’t make one iota of difference – other times semantic precision is of primary importance.

You’ll only get a good grasp of it through experience.