MSDN Documentation

Working with XML in Windows Programming

This documentation provides a comprehensive guide to using XML technologies within the Windows development environment. XML (Extensible Markup Language) is a widely used standard for structuring, storing, and transmitting data. Windows offers robust support for XML processing through various APIs and technologies, enabling developers to build sophisticated data-driven applications.

Whether you are parsing configuration files, exchanging data between applications, or creating complex document structures, understanding Windows XML programming is essential for modern software development on the platform.

Core Concepts

Before diving into specific APIs, it's important to grasp some fundamental XML concepts:

• Elements: Tags that define the structure of an XML document (e.g., <book>, <title>).
• Attributes: Name-value pairs that provide additional information about elements (e.g., id="123").
• Text Content: The data contained within an element.
• Root Element: The single outermost element in a valid XML document.
• Well-formedness: XML documents must adhere to strict syntax rules (e.g., all tags must be closed).
• Validation: Checking if an XML document conforms to a specific schema (like DTD or XML Schema).

XML DOM (Document Object Model)

The DOM is a programming interface for XML documents. It represents the document as a tree structure, allowing you to navigate, access, and modify its content programmatically. Windows provides the COM-based Microsoft XML Core Services (MSXML) library, which is a powerful implementation of the DOM.

Key operations include:

• Loading XML from a file or string.
• Traversing the node hierarchy (elements, attributes, text).
• Querying for specific nodes using XPath.
• Modifying the document (adding, deleting, changing nodes).
• Saving the modified document.

Example (Conceptual C++):

#include <msxml6.h>

// ... Load XML document into an IXMLDOMDocument object
// ... Traverse nodes, read/write data
// ... Save changes
                

XML SAX (Simple API for XML)

SAX provides an event-driven approach to XML parsing. Instead of building an in-memory tree, SAX parsers notify your application of events as they encounter different parts of the XML document (e.g., start of an element, character data, end of an element). This is more memory-efficient for very large XML files.

You typically implement handler interfaces to process these events.

XPath (XML Path Language)

XPath is a query language for selecting nodes from an XML document. It uses path expressions to navigate the document's structure and filter nodes based on various criteria. MSXML and other XML parsers integrate XPath support for powerful data retrieval.

Example XPath expression: //book[@category='fiction']/title - selects all title elements that are children of book elements with a category attribute equal to 'fiction'.

XSLT (Extensible Stylesheet Language Transformations)

XSLT is a language for transforming XML documents into other formats, such as other XML documents, HTML, or plain text. It uses XSLT stylesheets to define the transformation rules.

This is particularly useful for:

• Generating reports from XML data.
• Converting XML to web pages.
• Restructuring XML data.

XML Namespaces

Namespaces are used to avoid naming conflicts in XML documents, especially when combining XML from different sources or using predefined vocabularies. They provide a way to qualify element and attribute names with a URI.

XML Validation (DTD, Schema)

XML documents can be validated against a Document Type Definition (DTD) or an XML Schema (XSD). Validation ensures that the XML document conforms to a predefined structure and data types, improving data integrity and interoperability.

API Reference

Resources and Further Reading

• XML DOM Overview
• XPath Tutorial
• Introduction to XSLT
• XML Schema (XSD) Guide