XML (Extensible Markup Language) is a powerful tool for structuring data, but it rarely works in isolation. Its true power is unlocked by a suite of related technologies that allow you to define, validate, query, transform, and use that structured data in a standardized way.
Some XML-based technologies:
| Technology | Meaning | Description |
|---|---|---|
| XHTML | Extensible html | It is a clearer and stricter version of XML. It belongs to the family of XML markup languages. It was developed to make html more extensible and increase inter-operability with other data. |
| XML DOM | XML document object model | It is a standard document model that is used to access and manipulate XML. It defines the XML file in tree structure. |
| XSL it contain three parts: i) XSLT (xsl transform) ii) XSL iii)XPath | Extensible style sheet language | i) It transforms XML into other formats, like html. ii) It is used for formatting XML to screen, paper etc. iii) It is a language to navigate XML documents. |
| XQuery | XML query language | It is a XML based language which is used to query XML based data. |
| DTD | Document type definition | It is an standard which is used to define the legal elements in an XML document. |
| XSD | XML schema definition | It is an XML based alternative to dtd. It is used to describe the structure of an XML document. |
| XLink | XML linking language | xlink stands for XML linking language. This is a language for creating hyperlinks (external and internal links) in XML documents. |
| XPointer | XML pointer language | It is a system for addressing components of XML based internet media. It allows the xlink hyperlinks to point to more specific parts in the XML document. |
| SOAP | Simple object access protocol | It is an acronym stands simple object access protocol. It is XML based protocol to let applications exchange information over http. in simple words you can say that it is protocol used for accessing web services. |
| WSDL | web services description languages | It is an XML based language to describe web services. It also describes the functionality offered by a web service. |
| RDF | Resource description framework | RDF is an XML based language to describe web resources. It is a standard model for data interchange on the web. It is used to describe the title, author, content and copyright information of a web page. |
| SVG | Scalable vector graphics | It is an XML based vector image format for two-dimensional images. It defines graphics in XML format. It also supports animation. |
| RSS | Really simple syndication | RSS is a XML-based format to handle web content syndication. It is used for fast browsing for news and updates. It is generally used for news like sites. |
Defining and Validating Structure
These technologies are used to define the "rules" for an XML document, i.e. what elements and attributes are allowed, and in what order.
DTD (Document Type Definition)
A DTD is the original, classic standard for defining the legal building blocks of an XML document. It sets the rules for the document's structure, including the elements, attributes, and their relationships.
XSD (XML Schema Definition)
XSD is the modern, more powerful, and XML-based alternative to DTD. A key advantage of XSD is that it supports data types (e.g., integer, string, date), allowing for much more detailed validation.
Querying and Finding Data
These languages are used to navigate through an XML document and select specific pieces of information.
XPath (XML Path Language)
XPath is a language for finding and selecting nodes (elements, attributes, text, etc.) in an XML document. It uses a "path-like" syntax to navigate the document's hierarchical tree structure and is a core component used by both XSLT and XQuery.
XQuery (XML Query Language)
XQuery is to XML what SQL is to databases. It is a powerful language used to query collections of XML data, using XPath expressions to find the data and then providing additional features for filtering, sorting, and transforming it.
Transforming and Displaying Data
This technology is used to convert an XML document into another format, such as HTML for display in a browser.
XSLT (Extensible Stylesheet Language Transformations)
XSLT is a language for transforming an XML document into another document (e.g., XML to HTML, XML to another XML structure, or XML to plain text). It uses XPath to select parts of the source document and then applies rules to transform them into the desired output format.
Linking within XML Documents
These technologies provide a standardized way to create hyperlinks within and between XML documents.
XLink and XPointer
- XLink is a language for creating more powerful and flexible hyperlinks in XML documents than what is possible with HTML's
<a>tag. - XPointer works with XLink to allow hyperlinks to point to specific parts (fragments) inside an XML document.
XML in Web Services
XML is a foundational technology for many web service protocols.
SOAP (Simple Object Access Protocol)
SOAP is an XML-based protocol that lets applications exchange structured information over a network. It acts as a standardized "envelope" for sending messages between systems.
WSDL (Web Services Description Language)
WSDL is an XML-based language used to describe the capabilities of a web service. It acts as an "instruction manual," telling other applications what operations the service offers and how to communicate with it.
Languages Built on XML
The "Extensible" nature of XML means it can be used to create entirely new, specialized markup languages. Famous examples include XHTML, SVG, RSS, and RDF.