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Extensible Markup Language (XML)

Extensible Markup Language (XML)

XML stands for eXtensible Markup Language. It is extensible, because it does not use a predefined set of tags for identifying structural components. Instead, it provides a mechanism for defining such sets of tags. The main purpose of the language is to share data. Unlike HTML, in XML there is no predefined set of tags and tags specify meaning, rather than the presentation.

Syntax of XML

XML syntax refers to the rules that determine how an XML application can be written. XML syntax is very straight forward, and this makes XML very easy to learn.

XML documents must contain one root element that is the parent of all other elements:

<root>
  <child>
    <subchild>.....</subchild>
  </child>
</root>

XML must have a root element

The above syntax shows the root element which is necessary while writing XML code. This is shown in the following example:-

<?xml version="1.0" encoding="UTF-8"?>
<note>
  <to>Tove</to>
  <from>Jani</from>
  <heading>Reminder</heading>
  <body>Don't forget me this weekend!</body>
</note>

In this example, 'note' is the root element.

  • Advantages of using XML:

    • Simplicity - XML documents are ordinary text files that can be created and edited with any text editor.
    • Vendor independence
    • Platform independence
    • Extensive infrastructure

  • Disadvantages of using XML:

    • Verbose and cumbersome syntax
    • Highly inefficient storage

In Computer Language, eXtensible Markup Language(XML) is that which defines a set or block of rules which are later used for encoding documents in such a format which is both machine and human readable.

XML was replaced by JSON as the main language for transferring data but XML is still widely used to create user interfaces for Android, JavaFX and general GUI design due to its expressive quality. The following example is a view created with a framework called SAPUI5 that uses XML:

          <m:FlexBox wrap="NoWrap" fitContainer="true" alignItems="Center" class="sapUiTinyMarginEnd">
            <m:Title text="{products>Name}" wrapping="true" class="sapUiTinyMarginEnd"/>
          </m:FlexBox>

As you can see, XML is quite similar to HTML, but the difference lies in the functionality.

There is a main thing between XML and HTML which makes them different from each other. It is that XML was designed to carry a particular information and focuses on that informaion only. And HTML focuses on displaying that particular Information like design and all these stuff regarding the information.

There are two primary differences between XML and HTML:

  1. XML was designed to describe data; whereas, HTML was designed to display data.
  2. HTML uses predefined tags while XML uses user defined tags.

XML helps simplify:

  1. data sharing
  2. data transport
  3. platform changes
  4. data availability

It became a W3C Recommendation as early as in February 1998!

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