Introduction to XML - Database Design - Lecture Slides, Slides of Database Management Systems (DBMS)

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Introduction to XML

XML

• XML stands for Extensible Markup Language
• XML was designed to carry data
• XML and HTML designed with different goals
  • HTML designed to display data
  • XML designed to describe data and focus on what data is
• XML tags are not predefined.

Importance of XML (cont’d)

• Easily Processed

• Regular and consistent notation
• Vendor-neutral standard

• Hierarchical

• Faster to access
• Easier to rearrange

XML Building blocks

• Element
  • Delimited by angle brackets
  • Identify the nature of the content they surround
  • General format: …
  • Empty element:
• Attribute
  • Name-value pairs that occur inside start-tags after element name, like:

XML Syntax

• All XML elements must have a closing tag
• XML tags are case sensitive
• All XML elements must be properly nested
• All XML documents must have a root tag
• Attribute values must always be quoted
• With XML, white space is preserved
• With XML, a new line is always stored as LF
• Comments in XML:

An example of XML

Tom

Jane

XML Attributes

• Located in the start tag of elements
• Provide additional information about

elements

• Must be enclosed in quotes

XML Validation

• "Valid" XML document
  • “well formed”
  • Conforms to the rules of a DTD (Document Type Definition)
• XML DTD
  • defines the legal building blocks of an XML document
  • Can be inline in XML or as an external reference

XML Application1 (cont’d)

XML Application1 (cont’d)

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XML Application

• XML is used to Exchange Data
  • Text format
  • Can be read by many different types of applications
  • Software-independent, hardware-independent
  • Exchange data between incompatible systems, given that they agree on the same tag definition.
• Benefits:
  • Reduce the complexity of interpreting data
  • Easier to expand and upgrade a system

XML Application

• XML can be used to Store Data
  • Plain text file
  • Store data in files or databases
  • Other clients and applications can access your XML files as data sources
• Benefits:
  • Accessible to more applications