Document Definition Markup Language (DDML) is an XML schema language that was proposed in 1999. Originally, DDML was intended to replace XML DTDs by using elements and attributes to describe a schema. However, it never gained popularity among developers.
Despite this, DDML served as a foundation for the development of other XML-based schema languages. Some of these include the successful XML Schema and RELAX NG.
It is important to note that DDML did not offer any significant benefits over DTDs aside from providing a more robust framework for describing element/attribute hierarchy.
What is the History of DDML?
DDML was first proposed by various participants in the xml-dev electronic mailing list in 1999. Its original name was XSchema, which aimed to use elements and attributes instead of declarations to describe a schema. Later, the name was changed to DDML to follow a less ambitious goal of focusing on the basic element/attribute hierarchy.
Instead of offering additional functionality than DTDs, DDML served as a framework for the development of different XML-based schema languages.
What are the Benefits of DDML?
Compared to DTDs, DDML provided a more robust framework for describing the basic element/attribute hierarchy.
What are the Alternatives to DDML?
Some of the successful alternatives to DDML include XML Schema and RELAX NG.
Final Thoughts
DDML may not have gained popularity among developers, but its development provided the groundwork for the development of other XML-based schema languages. XML Schema and RELAX NG are two successful examples of schema languages that were influenced by DDML and continue to be used to this day.
Frequently Asked Questions (FAQs)
- Is DDML still in use today?
No, DDML is not commonly used today. However, it served as the foundation for the development of other XML-based schema languages such as XML Schema and RELAX NG.
