What Is XML (Extensible Markup Language)? Meaning, Elements, and Benefits

• Extensible Markup Language (XML) is defined as a markup language that outlines the rules and protocols used to define, store, and share data between computer systems.
• This article explains XML in detail, its key elements, and its advantages.

What Is XML?

Extensible Markup Language (XML) is a markup language that outlines the rules and protocols used to define, store, and share data between computer systems. These rules simplify data exchange between websites, applications, and databases on any network. Owing to their human and machine readability, the parties involved in data sharing can easily read and decipher the data hidden within XML files.

XML language lacks the ability to perform data computing operations. Instead, it relies on other programming languages or software to do so. As a result, it ensures the structured data management of documents and files. For example, consider a simple word document that allows you to add suggestions through comments. The comments could be:

• Make the subhead italics.
• Change the author’s name.
• Update the header and footer of the doc.

Comments like these enhance the usability of the text without fiddling with the document content. Like the above example, XML relies on markup symbols or tags that give additional information about the underlying files. Using this information, other software or applications can perform data processing tasks more efficiently. It also ensures the data integrity of structured data.

XML tags

Under XML, the markup symbols, also called tags, define data or files. Let’s understand it with an example. To represent movie data that is based on a novel, you can create tags such as <movie>, <name>, and <novel>. The corresponding XML document for a movie (e.g., Harry Potter) may have the following content:

<movie>

<name>Harry Potter</name>

  <novel>J. K. Rowling</novel>

</movie>

XML tags such as these enable systematic data coding that reveals the information flow across computing systems. This implies that software can use these tags to determine the data processing strategies of the document. For example, you can determine how the document or file should be processed, the order of processing, and even the order of file display.

These tags or elements are fundamental to XML. Even if you transfer XML files across different networks or platforms via the internet, the recipient system can still parse the data within those XML files. This is primarily due to the standardized XML format, which remains the same across systems.

Moreover, XML enables you to create or define your own language. For example, languages such as XHTML, Mathematical Markup Language (MathML), and SVG are created using XML meta-language.

XML vs. HTML

HTML language was specifically designed to display documents on web browsers. However, as mobile devices emerged, displaying data on them became complicated. Moreover, complex tasks such as translating file content from one language to another were nearly impossible. It was evident that HTML had a serious bottleneck since the language was primarily designed only to create web documents that could be shared with others.

XML came to the fore as a successor to HTML. It not only suited web applications but could carry out other complex tasks such as translating documents between different languages or displaying content on devices with different screen sizes. Unlike HTML, which was designed to present and display data, it could store and transport data. Also, HTML uses predefined tags, whereas XML allows you to create and define your own tags.

In summary, HTML can be termed as the language used for document presentation, while XML is meant for document description.

See More: What Is COBOL Programming Language? Definition, Examples, Uses, and Challenges

Key Elements of XML

An XML file is similar to any text document that allows you to write and save data. It has a ‘.xml extension.’ The file can be created or edited by using any one of the following:

1. Notetaking apps or editors such as Notepad or Notepad++
2. Any web-based XML file editor, such as Emacs or Adobe FrameMaker
3. Browsers or other communication software

A typical XML file is made up of the following key components:

 

XML Key Elements

1. XML document

An XML file begins with the <xml></xml> tags. The data written in between these tags is part of an XML document. XML processing software uses these specific tags as reference points to compute the XML code.

2. XML declaration

An XML file has an opening declaration that defines the XML version used in the document. It initiates the XML processor to parse the XML document. It has the following syntax:

<?xml

   version = “version_number”

   encoding = “encoding_declaration”

   standalone = “standalone_status”

?>

Here version = XML standard version, encoding = character encoding, standalone = data that informs the parser if the XML document uses information from an external source.

A simple example of this syntax could be:

<?xml version=”1.0″ encoding=”UTF-16″ standalone=’yes’?>

3. XML elements

The remaining tags within the XML document, excluding the tags of the above components, are labeled as XML elements. These contain features such as text, attributes, and other XML file elements. The root element marks the beginning of the XML document.

For example, let’s write an XML code that identifies office managers that intend to attend the office New Year party.

<NewYearPartyList>

<office>

    <managers>

    <name>Albert</name>

     <name>Newton</name>

    </managers>

</office>

</NewYearPartyList>

Here, <NewYearPartyList> defines the root element, whereas the office and managers are regarded as other element names.

4. XML attributes

XML attributes refer to the descriptors that provide details of the XML elements. You can write the attribute names and the corresponding values under quotation marks.

For example,

<Albert height=“173”>

5. XML content

Data embedded within XML files are referred to as XML content.

For example,

<brother>

    <name>Donald</name>

    <name>Brenden</name>

</brother>

Here, the values Donald and Brendon are described as XML content.

6. XML schema

XML schema sets boundaries to the XML file structure. It expresses rules and constraints that need to be obeyed by the XML document.

For example,

• The order of XML elements is defined through text grammar rules
• The criteria that the XML content needs to fulfill (i.e., Yes or No conditions)
• Data types of XML content

Consider an XML schema for a library that sets out the following constraints:

A library element may have the attributes of book and subject.

1. The library element will fall under a nested category element and will also have an attribute name
2. The author of a book will be a separate element under a nested library element

The above constraints are met by writing an XML code as below:

<category name=“Science”>

<library book=“The Biology of Belief”, subject=“Consciousness”>

<author>Bruce Lipton</author>

</library>

</category>

XML schemas allow software applications to create and manage XML files easily. Industries generally indulge in inter-business data transfer. As a result, several companies implement XML schemas that align with their business operations and help reduce the efforts and resources poured into writing XML code specific to information exchange.

For example, Scalable Vector Graphics (SVG) is an XML-based language that specifies vector graphics-related constraints. Developers use SVG language to meet industry requirements and satisfy data transfer needs that may pop up in future business scenarios.

7. XML parser

XML parser refers to software that validates XML files by evaluating their syntax. Subsequently, it processes or reads XML documents to extract relevant information. Moreover, it also checks whether the XML file obediently follows XML schema rules.

In case of syntax errors, the parser rejects the XML file and does not process it. For example, the XML parser gives errors in the following situations:

• Missing opening or closing tags
• XML attributes without quotation
• XML file does not meet schema constraints

See More: Web Developer: Job Description, Key Skills, and Salary in 2022

Advantages of Using XML

Computing systems in the real world often face the problem of managing incompatible data formats. As a result, communication and data sharing between discrete sets of devices and databases are hampered. In such cases, XML provides a worthwhile solution that bridges the communication gap between enterprises.

Let’s look at some of the key advantages of using XML.

XML Advantages

1. Drives inter-business deals

Companies tend to collaborate by selling their services or goods to each other. Such business tie-ups happen against the backdrop of strong information exchange between the participating entities. To enable smooth business transactions between the two, information such as service costs, product specifications, or delivery schedules need to be communicated in a timely and understandable manner.

This is where XML plays a pivotal role. XML enables the sharing of information between companies in an electronic format. Organizations can rely on it to push and promote business dialogues without human intervention.

2. Ensures data integrity

XML ensures that data integrity is maintained while data exchange happens across multiple operating systems, applications, or browsers. This is due to the ability of XML to transfer data description along with the data itself. An XML file’s descriptive information can be used for the following purposes:

• To evaluate data accuracy
• Present data in a customized manner to different users
• Maintain consistency in data storage across multiple platforms.

3. Optimizes search operations

With XML, programs underlying search engines can classify and segregate XML documents more efficiently than any other document type. For example, a word can act as a noun or adjective based on where it is used in a sentence. Search engines use XML tags to classify them accurately based on their usage. As a result, the search engine shows relevant search results and eliminates nonsensical ones. Hence, XML is key to improving search efficiency, enabling computers to interpret natural languages appropriately.

4. Supports flexible applications

Several modern technologies have built-in support for XML. This allows you to modify or upgrade the design of applications with ease. With XML support, XML documents can be read and processed without making any changes to the data format of the databases.

5. International standard

XML is a standard managed by the World Wide Web Consortium (W3C), which focuses on implementing web standards. It is not linked to any specific company or application. Moreover, owing to the flexible nature of XML, files can be created and edited via any text or XML editor on any platform. As a result, XML documents are suitable for distributed applications that demand a common data representation format.

6. Allows content reuse

XML language supports content reuse. This means you can create an XML document and later reuse the document’s content to create different documents supported across varied platforms or applications. It saves companies a lot of money, as XML files, once created, can be reused repeatedly for different applications that suit different audiences.

For example, eXtensible Stylesheet Language Transformations (XSLT) is an XML specification designed to transform XML files into other formats, such as HTML, making the XML content reusable for web applications, mobile applications, social media, and even Web 2.0 contexts.

Another example is that of DITA (OASIS Open Darwin Information Typing Architecture). This XML-based standard was originally developed by IBM in the 2000s to structure, publish, and reuse the content in the product documentation. DITA reduces the chances of human error (i.e., copying and pasting) while documenting products. Moreover, it provides an automated way to synchronize content updates across different product documents. Top companies like Cisco, Nokia, Oracle, and IBM used DITA extensively for technical documentation.

7. Updates formatting style

The XML file format stays isolated from the XML content. This implies that the XML formatting files are placed in separate stylesheets. Such functionality allows you to update the document format whenever the need arises without worrying about the XML content. Moreover, different sets of documents can thereby adopt a consistent formatting style.

8. Promotes efficient XML document writing

XML supports multi-language publishing. It allows you to work on different language documents derived from a single XML source file. As a result, the cost of language translation is reduced significantly. Hence, creating and publishing documents in varied languages is possible with XML. Moreover, you need not worry about the document format as the original formatting style of XML files is readily applied to new documents when you publish the document.

Key applications of XML

XML technology is used across a variety of applications, right from simple text processing software, web publishing applications, and online businesses, to complex software configuration management. Companies such as Salesforce, Foretag, Scopeland Technology GmbH, and many others use XML for web, e-business, and portable applications.

Let’s look at some key XML applications in today’s modern world.

• Online publishing: XML is often used to create intuitive yet customized ecommerce applications that involve interactive web pages. XML allows one-time content creation that can be leveraged across devices or views. For example, XSLT processors determine the format in which the XML content is to be rendered.
• Efficient web searching: Consider HTML-based web pages as an example. Let’s say you perform a web search for research papers authored by Stephen Hawking on a search engine. In this case, the search results can have instances where the word ‘Hawking’ is taken out of context. However, the XML language resolves this issue by assigning an appropriate tag (<author> tag). This ensures that web searches reveal only relevant results.
• Business applications: XML is key to electronic data interchange (EDI) between businesses and potential customers. It is a mode of information exchange that guides inter-business transactions.
• Ubiquitous computing applications: XML ensures that applications and devices of different kinds can store, display, reuse, and share data between them. This includes computing devices such as smartphones, PDAs, and others.

Additionally, several other XML-based standards, such as Wireless Markup Language (WML) and VoiceXML, are developed to extend the XML functionality to ubiquitous computing applications. VoiceXML is a standard that develops distributed voice applications, whereas, the WML standard focuses on making web content accessible on handheld devices such as cell phones with bandwidth limitations.

See More: What Is Integrated Development Environment (IDE)? Meaning, Software, Types, and Importance

Takeaway

XML is a data description language that defines data within markup symbols or tags. The hierarchical language is used to store and share data between network systems. Owing to its flexible nature, language standards are omnipresent, from technical documentation to computer-related graphics.

Did this article help you understand XML’s role in enterprise computing? Let us know on FacebookOpens a new window , TwitterOpens a new window , or LinkedInOpens a new window . We’d love to hear from you!

Image source: Shutterstock

MORE ON WEB TECHNOLOGY

• Cobol Programmer: Job Description, Key Skills, and Salary in 2022
• What Is SQL? Definition, Elements, Examples, and Uses in 2022
• Top 10 SQL Courses in 2022
• Java vs. JavaScript: 4 Key Comparisons
• What Is NoSQL? Features, Types, and Examples