XML Overview
XML, which stands for eXtensible Markup Language, is a markup language designed to store and transport data in a format that is both human-readable and machine-readable. Unlike HTML, which is designed to display data, XML focuses on the structure of data, allowing developers to define their own tags and document structure.
History of XML
The development of XML began in the mid-1990s as a response to the limitations of HTML in handling complex, structured documents. Here's a brief timeline:
- In 1996, the World Wide Web Consortium (W3C) formed the XML Working Group to develop the language.
- XML 1.0 was officially released in February 1998.
- XML 1.1 was released in February 2004, addressing issues in internationalization, but XML 1.0 remains more widely used due to its stability and backward compatibility.
Key Features of XML
- Self-Describing: XML documents can be easily understood by both humans and machines due to the use of tags that describe the data.
- Extensible: Users can define their own tags and document structure, allowing for great flexibility in data representation.
- Platform Independent: XML can be processed by any application that understands XML, regardless of the platform.
- Unicode Support: XML uses Unicode for characters, making it suitable for international use.
- Validation: XML documents can be validated against a DTD or XML Schema to ensure they conform to a defined structure.
XML Usage and Applications
XML is used in various applications:
- Data Exchange: XML is commonly used for exchanging data between different systems, especially in web services and APIs.
- Configuration Files: Many software applications use XML for storing configuration settings.
- Document Markup: XML can be used for marking up documents in fields like publishing, scientific research, and legal documents.
- Web Services: Technologies like SOAP and REST use XML for message formatting.
Standards and Specifications
Several standards and specifications are associated with XML:
- XSLT (Extensible Stylesheet Language Transformations) for transforming XML documents into other formats.
- XPath for navigating through elements and attributes in an XML document.
- XQuery for querying and extracting data from XML documents.
- XML Namespaces to avoid naming conflicts in XML documents when using multiple vocabularies.
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