What is XML?

Category: Programming | Posted date: 2023-04-02 18:32:19 | Posted by: Admin

A markup language and file format for storing, transmitting, and reconstructing arbitrary data is called extensible markup language.



What is XML?

A markup language and file format for storing, transmitting, and reconstructing arbitrary data is called extensible markup language. It provides a set of instructions for encoding documents in a way that is readable by both machines and people.

The main purpose of XML is to produce data formats that are used to encode data for entries in databases, transactions, and many other kinds of data. By developing various kinds of content — such as web, print, and mobile content — that are based on XML data, different content types can be created using XML data.


XML elements

All of the data in an XML file must be contained within the root element, also known as the document element, for the file to function logically. The root element in the example above is library>, and it indicates the sort of data that is present in the file.

In the example above, the root element includes book> elements, which are composed of the two elements title> and author>. These other elements describe the various sections of the XML document.

For an XML file to be regarded as well-formed, all XML elements must be correctly terminated. This implies that a tag must properly end with an opening and closing tag, as in the case of the following sentence, which would be included in a document:

<para>This is an illustration of a paragraph's XML tag.</para>

In the event that a tag is null, a forward slash is used to end it. In this illustration, an extra space is added to a text using an empty self-terminating paragraph tag:

<para />

If necessary, users of XML can define their own unique additional elements. An XML author could create new elements in the example above for the publisher, publication date, ISBN, and any other pertinent information. The elements can also be defined to impose limitations on their contents.

XML entities

XML components can also contain predefined entities, which are used for distinctive restricted XML characters. Custom entities can be described in an XML file to insert a predefined string of characters.

The following five XML entities are the usual predefined ones:

  1. &lt; - XML typically uses the less than symbol (), also referred to as the open angle bracket, to denote the beginning of an XML element. When the open angle bracket is included in the XML file's text, this entity is used.
  2. &gt; - XML typically uses the greater than symbol (>), also referred to as the close angle bracket, to denote the conclusion of an XML tag. When the close angle bracket is included in the XML file's text, this entity is used.
  3. &amp; - The ASCII ampersand symbol (&) is solely employed in XML to indicating the start of an XML item. This entity is used whenever an ampersand appears inside an XML element.
  4. &quot; - The ASCII double quote character (") is used to indicate an element's optional attribute values in XML element tags. An emphasis> element, for instance, can provide options for bolding, italicizing, or underlining particular text. This entity is used whenever a double quotation mark appears in the text of an XML element.
  5. &apos; - In XML element tags, the ASCII single quotation character ('), often known as an apostrophe, is used to denote the element's option attributes. For instance, an emphasis> tag can offer options for bolding, italicizing, or underlining certain text. When a single quotation or apostrophe appears in the text of an XML element, this entity is used.

The format of the entity name for an XML entity is &name;, which starts with the ampersand symbol and ends with a semicolon. Bespoke entities can be simple XML components or single characters. For instance, boilerplate language for legal contracts or technical documentation can be condensed into a single object. When incorporating an entity into an XML file, the XML author must make sure that the entity will provide well-formed XML data.



Advantages of XML

  • XML may be utilized on any system and enables technology change when it occurs because it is platform-neutral and programming language independent.
  • XML is Unicode-compatible. Each letter, digit, and symbol is given a distinct numeric value by Unicode, an international encoding standard for usage with many languages and scripts that is applicable across various platforms and programs. With the help of this functionality, XML can transport any data that is written in a human language.
  • Data that is saved and delivered using XML can be modified at any moment without having an impact on how the data is presented. The most common markup language for data presentation is HTML. HTML reads XML data and displays it on a GUI (graphical user interface). As data is updated in XML, it automatically updates in HTML without requiring any changes to the HTML GUI.
  • DTD and Schema are two methods for validating XML. The XML document is checked for syntax errors using this validation.


Disadvantages of XML


  • In contrast to JSON and other text-based data transport protocols, XML syntax is verbose and redundant.
  • The repetitious nature of the XML syntax causes increased storage and transit expenses when the volume of data is large.
  • Compared to alternative text-based data transfer formats like JSON, XML documents are less understandable.
  • An array is not supported by XML.
  • XML files tend to be somewhat large due to their verbose nature, however this fully relies on the author.


Important XML Standards

  • XML AJAX.
  • XML DOM.
  • XML XPath.
  • XML XSLT.
  • XML XQuery.
  • XML DTD.
  • XML Schema.
  • XML Services.


Final Thoughts

Even though machine learning and parallax scrolling are more exciting and innovative, XML is still one of the most important web technologies available today. Having a firm grasp of XML can help you understand how websites, including your own, convey material. You can leave the coding to developers.