SystemXml

System.Xml is a core namespace in the .NET Base Class Library that provides APIs for working with XML data. It offers a range of processing styles, including streaming, in-memory manipulation, and validation, to support diverse scenarios from simple parsing to large-scale document handling. The APIs are designed to conform to common XML standards, including XML 1.0 and support for namespaces and schema validation.

Key components of System.Xml include: XmlReader and XmlWriter for forward-only streaming access to XML data; XmlDocument for a DOM-style, in-memory representation; XPathNavigator and XPathDocument for XPath-based querying; XmlSerializer for converting between .NET objects and XML; and the System.Xml.Schema namespace with types such as XmlSchema and XmlSchemaSet to enable schema-based validation. The System.Xml.Xsl namespace provides XSLT transformation support via classes like XslCompiledTransform.

System.Xml complements related APIs in the .NET ecosystem, such as System.Xml.Linq, which delivers LINQ to XML through XDocument and XElement for a more query- and object-oriented approach. Both families of APIs reside within the .NET XML stack and can be used together in the same application as needed.

Deployment and platform coverage: System.Xml is part of the .NET Base Class Library and is available across the .NET Framework, .NET Core, and .NET 5+ runtimes. It emphasizes performance and interoperability with standard XML tooling and schemas. Typical use cases include reading configuration files, exchanging data with XML-based services, validating documents against schemas, and transforming XML with XSLT.