XML Validation II Advanced DTDs

1. XML Validation IIAdvanced DTDs Robin Burke ECT 360

2. Outline • Parameter entities • Parameterized DTDs • Modularized DTDs • Break • Namespaces • XML Schemas • Elements • Attributes

3. Entities • Internal general entities • macros • External general entities • "include" mechanism • Parameter entities • for DTD organization

4. Internal general entities • Declaration <!ENTITY disclaimer "This is a work of fiction. Any resemblance to persons living or dead is unintentional."> • Use &disclaimer;

5. External general entities • Declaration <!ENTITY standardContract SYSTEM "stdContract.xml"> • Use <comment>... transaction subject to the following contract terms: &standardContract;</comment>

6. General entities • Process model • The entity string is replaced by the contents • And then parsed by the XML parser • Resulting document tree • same as if the text were part of the original document

7. Parameter entities • Similar macro function • Inside the DTD • Uses • Organizing common element / attribute models • Documenting data types • Simulating namespaces • Making DTDs modular

8. Conditional sections • To control the inclusion of DTD sections • This will be processed • <![INCLUDE[ ... ]]> • This will be omitted • <!IGNORE[ .. ]]> • Doesn't seem that useful BUT • combined with entities • we can modularize our DTD

9. Modular DTD • Same DTD can be used for multiple document types • A few parameters are redefined and the DTD is different

10. Example

11. Parameter entities • Powerful facility for DTD organization and application • Real-world applications • parameterize DTDs • use modular DTDs

12. Example • DTDs • Document • Problem • how to import the namespaces?

13. Solution • Fully-qualified names everywhere • yuk! • Parameterized DTD • with namespace defined in an entity

14. Next week • Document Engineering • on-line reading • Quiz #1 • DTDs