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DTD Parser

The XML specification includes both XML and DTD within its scope. Within an XML document's <!DOCTYPE>, there can be an internal subset of the DTD, or an external DTD can be referenced. In order to fully comply with the XML 1.0 specification (and/or XML 1.1), a XML parser must also be a DTD parser.

Stylus Studio® contains several such parsers, each of which is used as the occasion demands.

DTD Editor Parser

The DTD Editor, with it's Text and Tree editing modes, uses a DTD parser to read the initial file and process it for Sense:X (intelligent XML editing) support.

DTD Validation Parsers

In addition to the internal DTD parser which can be used to validate files against DTDs, Stylus Studio® includes other validation engines that can parse and validate DTD-using XML documents:

• Microsoft MSXML 4.0 DOM Parser
• Microsoft MSXML 6.0 DOM Parser
• Apache Xerces-J Parser
• Microsoft .Net System.Xml Parser
• Xerces-C++ Parser (internal), also from the Apache XML Foundation

So, counting the internal DTD parser, that gives several different ways to parse and validate. This helps you to ensure if there are any corner cases or gray areas (or even bugs in some validator), you'll have spotted them before deploying your DTD.

(The internal parser is triggered by just hitting the button without hitting the dropdown arrow next to it.)

SAX Parsing of DTDs

When an XML file is parsed, there is an option on the SAX interface to retrieve certain DTD events. More information can be found at the SAX Project Extensions pages.

DOM Parsing of DTDs

The DOM Level 3 Core API includes objects and methods for navigating both XML and DTD documents, as well as XML documents refering to internal DTD subsets or external DTDs. The Document Object Model (DOM) can be used in your own application from a variety of languages, including Java, C++, Python, and ECMAScript (also known in some circles as JScript or JavaScript).

DTD to XSD Parsing

Another area where a DTD parser is used is in the Document Wizards, namely converting DTDs to XML Schema documents and in creating sample XML documents from DTDs.

As you can see from these statements, Stylus Studio® uses several forms of DTD Parsing technology, in Java, C++ and .Net, both to validate and to serve as a template for XML instance creation. To explore more, download and experiment with your own free copy of Stylus Studio®.

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