XML, XSLT, and SQL Server XML Development

Custom XML, XSLT, and SQL Server XML Development

While JSON has become the default choice for most modern web APIs, XML remains an important technology for hierarchical, semi-structured data. It’s still the standard in specific domains: enterprise and legacy system integration, SOAP-based web services, document formats, configuration files, and industries such as finance, healthcare, and publishing where XML-based data standards are established. .NET and SQL Server both provide mature tooling for working with XML when it’s the right fit for a project.

XML and SQL Server

SQL Server has supported XML as a native data type since SQL Server 2005, allowing relational data to be exposed, queried, and stored as XML directly within the database. This includes the ability to query XML data using XQuery and XPath expressions, validate XML against XML Schema Definitions (XSD), and shred XML documents into relational row sets for use in standard SQL queries. Earlier SQL Server versions relied on a separate add-on called SQLXML, along with XDR (XML-Data Reduced) schemas, to map XML views to database schemas. Both are now legacy: Microsoft deprecated XDR schemas in favor of XSD schemas, and the native XML data type has largely replaced the need for the standalone SQLXML toolkit in modern development. Projects that still rely on SQLXML or XDR schemas should plan to migrate to the native XML data type and XSD schemas.

Where XML Still Makes Sense

XML remains a strong choice in several common scenarios:

• Enterprise and legacy integration: many established B2B and A2A systems still communicate over SOAP-based web services, which use XML as their message format.
• Document formats: formats like Office Open XML (.docx, .xlsx) and various publishing and content standards are built on XML.
• Configuration files: many enterprise applications and platforms still use XML for structured configuration.
• Content management: XML’s ability to represent hierarchical, semi-structured content while preserving its native format makes it well-suited to storing, querying, and transforming documents without flattening their structure.

For new public-facing APIs and services, JSON is typically the more practical choice today. The right format ultimately depends on the systems you’re integrating with and any standards your industry requires.

XML Development on .NET

The .NET platform provides robust support for working with XML through the System.Xml namespace, which includes stream-based and document object model (DOM)-based approaches for reading, writing, and validating XML documents. Its key sub-namespaces are:

• System.Xml.Schema — classes for working with XML Schema Definition (XSD) language, used to validate document structure
• System.Xml.Xsl — classes for performing Extensible Stylesheet Language Transformations (XSLT), used to convert XML into other formats
• System.Xml.Serialization — classes for serializing objects to and from XML documents or streams
• System.Xml.XPath — classes for navigating XML documents using XPath expressions

These namespaces are available across modern .NET as well as the legacy .NET Framework, so existing XML-based logic can generally be carried forward as applications are modernized.

XML Development at Diatom Enterprises

Diatom Enterprises is an outsource software development company experienced in working with XML, whether that means building new XML-based integrations, working with XML data in SQL Server, or migrating legacy SQLXML implementations to modern, supported approaches. Our developers have used XML in projects including the Online DSA Training System. Leave your contacts to discuss all the details of your project.