After reading this chapter, the reader will understand:

  • Structured, Semi-structured, and Unstructured data
  • Roles of tags in markup languages like Hyper-Text Markup Language (HTML) and Extensible Markup Language (XML)
  • Shortcomings of HTML that makes it unsuitable for applications that require exchanging documents
  • The reason that why XML is a suitable language for data representation as well as data exchange
  • The structure of XML data and the two main constructs used by XML document, that is, elements and attributes
  • When an XML document is considered well-formed and valid
  • Document type definition (DTD) and its limitation
  • XML Schema and the notion of XML namespace
  • Querying XML data using XPath and XQuery
  • The For, Let, Where, Order ...

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