XML is an open-source technology that is officially maintained by the W3C, and it is at Version 1.0 If you want to read the XML standard, then, visit the link to W3C website – Extensible Markup Language (XML) 1.0 (Fifth Edition) (w3.org).
The XML technology is a subset of SGML technology that has a goal to send, receive and process information across the web that HTML could not do. It has interoperability with SGML and HTML.
XML Inspired Technologies
A number of technologies are inspired by XML including HTML documents. XML itself is best way to handle data or information across web, but a number of other technologies also required to assist in the process of creating, displaying, sending, receiving and processing documents.
For example, Cascading Style Sheet (CSS) is web specifications that tell how to format and display the XML document for human users. These auxiliary technologies are classified into:
- XML Core Syntax
- XML Applications
- Document Modeling Techniques
- XML Query Language
- XML Styling and Transformation
- XML Programming Interface and Document Object Modeling (DOM)
We will briefly discuss each of these technologies and understand how they related to XML documents.
XML Core Syntax
The XML core syntax contains all the rules for creating XML documents. It has information from XML specifications like roots element, namespaces (to avoid name conflicts), character encoding, and Xlink, a language to create hyperlinks or link documents together and other rules for XML documents.
Earlier I mentioned that the XML application is any application that has a markup language just like the XML. The technologies like HTML, XHTML, a version of HTML that incorporates the features of XML, and MathML (a mathematical equation language). The MathML is quite popular when you want to display math equations in your documents. You note that the XHTML is stricter version of HTML and does not entertain incomplete or missing tags in HTML documents. It wants all HTML documents to be well-formed, unlike HTML.
Document Modeling Techniques
In a previous article, I have discussed about the importance of defining the XML document for making it a valid and well-formed document. The freeform XML rules are limited in that aspect. The two techniques to achieve this are document type definition (DTD) and Schema definition. You will learn more about these in detail.
XML Query Language
Sometimes we need to search and locate the information inside of an XML document. There are many ways to locate the desired information, for instance, XPath is the path to the data inside an XML document, similarly, XPointer link to a specific part of the document using Xlink and XPath.
What SQL (Structured Query Language) is form databases, XQL (XML Query Language) is for XML documents. It directly queries the document and get the desired results.
XML Styling and Transformation
There are four different ways to style the XML documents. These technologies are Cascading Stylesheet (CSS), XML Stylesheet Language (XSL), XSL Transformation Language (XSLT), and Extensible Stylesheet Language for Formatting Objects (XSL-FO).
XML Programming Interface and Document Object Modeling (DOM)