Validating XML: DTD, XML Schema, and Ensuring Data Integrity

Intermediate

✅ XML Validation: DTD & XML Schema (XSD)

Validation is critical to ensure that XML documents conform to defined rules and data integrity standards. There are two primary methods:

📜 DTD (Document Type Definition)

A set of declarations specifying allowed elements, attributes, and their relationships.

<!DOCTYPE note SYSTEM "Note.dtd">

➡️ DTD is simple but limited in expressing data types.

🧬 XML Schema (XSD)

An XML-based language that provides rich data typing, constraints, and namespace support.

Example snippet from an XSD:

<xs:element name="price" type="xs:decimal" />

➡️ XML Schema offers detailed validation capabilities suitable for complex data models.

🔍 Validation can be performed using parsers that validate against DTDs or Schemas, ensuring data correctness before processing or storage.

🚫 Proper validation prevents malformed data from causing errors downstream.