An Introductory Guide to EXtensible Markup Language (XML)

An Introductory Guide to EXtensible Markup Language (XML)
XML is an abbreviation of EXtensible Markup Language. It is a text-based markup language derived from Standard Generalized Markup Language (SGML). In this guide, we will learn all the fundamentals of XML. 

As we know, data is the most important element. Therefore, XML is also very important because it was designed to store and transport data and also to organize data as a structure. So, let’s begin with definition to XML to help understand it well.

What is XML?

As its name suggests, XML is a markup language. Its specification was created by the World Wide Web Consortium (W3C), the body that sets standards for the web. As a process, XML tags identify the data and are used to store and organize the data. 

Well, it was said that XML is going to replace HTML in the future, but it is not true as XML introduces new possibilities by adopting many successful features of HTML.

Here are some important characteristics of XML, which make it useful in a variety of systems and solutions.

  • XML is extensible 
Using XML allows us to create our self-descriptive tags or language, which suits our application.

  • XML does not display data but carries it 
Also, it allows us to store the data irrespective of how it will be presented.

  • XML is a public standard 
XML is available as an open standard.

Some Key Points:

1. It was released in the late 90s to offer an easy to use and store self-descriptive data.
2. On February 10, 1998, it became a W3C recommendation.
3. It is designed to be self-descriptive.
4. XML does not display data, but it carries data.
5. Tags in XML are not predefined. We need to define our tags.
6. It is language as well as platform independent.

However, as we mentioned earlier, XML is a markup language that defines a set of rules for encoding documents in a format which is both machine and human-readable. 

What is a Markup Language? 

Information added to a document which enhances its meaning in certain ways is what we call Markup. Basically, in that, it identifies the parts and how they relate to each other. More specifically, a set of symbols which can be placed in the text of a document to demarcate and label the parts of that document is a markup language. 

Below is an example that shows how XML markup looks while embedded in a piece of text −

   <text>Hello, world!</text>

Here we can see the markup symbols, or the tags like <message>...</message> and <text>... </text>. The tags <text> and </text> surround the text, and <message> and </message> mark the start and the end of the code.

Why XML?

XML is platform and language independent. The key advantage of XML is that we can use it to take data from a program like Microsoft SQL, and then convert it into XML. Further, we can share that XML with other platforms and programs. Also, we can communicate between two platforms that are generally very difficult.

Additionally, XML is truly powerful because of its international acceptance, especially, for databases, office application mobile phones, programming, and more. Many corporations use XML interfaces. It is because of its platform-independent feature.

XML Simplifies Things

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

There are times when computer systems contain data in incompatible formats. And, exchanging of that data is a time-consuming task for web developers. Due to that, large amounts of data must be converted, and incompatible data is often lost.

So, XML stores data in plain text format. It offers software- and hardware-independent way of storing, transporting, as well as sharing data.

Also, this makes it easier to expand or upgrade to new operating systems, new applications, or new browsers, without even losing data. Because of XML, data can be available to all kinds of "reading machines" such as people, computers, voice machines, news feeds, and many more.

Is XML a Programming Language?

A programming language attains some grammar rules and has its vocabulary that is further used to create computer programs. These programs further instruct the computer to perform specific tasks. 

Since XML does not perform any computation or algorithms, it does not qualify to be a programming language. Generally, it is stored in a simple text file and is processed by special software which is capable of interpreting XML.

How to Use XML?

There are four ways in which we can use XML:

1. XML separates data from your HTML
2. XML stores data inside HTML documents
3. XML can help to exchange information
4. XML stores data in files or databases

Now, let’s learn all these ways in detail:

1. XML separates data from your HTML

As we use HTML pages to display data, data is often stored inside HTML pages. But while using XML, this data can be stored in a separate XML file. As a result, we can concentrate on using HTML for formatting and display only. And even our HTML code will not change due to changes in the underlying data.

2. XML stores data inside HTML documents

By using XML, we can also store data inside HTML pages (“Data Islands"). Though, still, we can concentrate on using HTML for displaying and formatting the data.

3. XML can help to exchange information

Conversion of data to XML reduces complexity and creates data, which can be read by different types of applications.

4. XML stores data in files or databases

Moreover, we can use XML to store data in files or databases. To store and retrieve information from the store, applications can be written. And, to display the data, generic applications can be used.

Major Differences Between XML and HTML

Generally, there are many differences between XML (EXtensible Markup Language) and HTML (Hyper Text Markup Language). Some of them are:

1. General Definition

  • HTML: To display data and focuses on how data looks, we use HTML.
  • XML: A software and hardware independent tool which we use to transport and store data. Moreover, it focuses on what data is.
2. Case Sensitive

  • HTML: It is not case sensitive.
  • XML: It is case sensitive.
3. Language

  • HTML: It is a presentation language.
  • XML: It is neither a programming language nor a presentation language.
4. Tags

  • HTML: It has its predefined tags.
  • XML: It gives the flexibility to define tags according to our need.
5. Whitespaces

  • HTML: It does not preserve whitespaces.
  • XML: It preserves whitespaces.
6. A Closing Tag

  • HTML: It is not necessary to use a closing tab while using HTML.
  • XML: It mandatory to use a closing tag in case of XML.
7. Character

  • HTML: Since it is used to display data, it is static.
  • XML: And since it is used to transport data, XML is dynamic.

XML Related Technologies

There are many technologies related to XML, some of them are:

1. XHTML(Extensible HTML)

This technology is a clearer version of XML. It was designed to make HTML more extensible and increase interoperability along with other data.

2. XML DOM (XML Document Object Model)

A standard document model which we use to access and manipulate XML. Generally, it defines the XML file in a tree structure.

3. XSL (EXtensible Stylesheet Language)

XSL transforms XML into other formats, like HTML. Especially, for formatting XML to screen, paper, etc., this is used. Moreover, it navigates XML documents.

4. XQuery(XML Query language)

To query XML based data, an XML based language XQuery is used.

5. DTD (Document Type Definition)

To define the legal elements in an XML document, this is used.

Best Uses of XML

Here we are listing some best uses of XML:

1. To simplify the creation of HTML documents for large websites, XML can work behind the scene.
2. Also, to exchange information between organizations and systems, we can use XML.
3. Moreover, for offloading and reloading of databases, XML can be used.
4. By using XML, we can store and arrange the data that can customize your data handling needs.
5. Moreover, we can merge XML with style sheets. This helps to create almost any desired output.
6. We can express any data as an XML document.

Beneficial Features of XML

There is no doubt that XML has been widely adopted. But then, the question arises- why? So, some of the key benefits and features of this language are:

1. Easy data exchange 

This could be one of the best features. XML allows the easy sharing of data between different applications. And, since XML is language and platform independent, no matter if these applications are written in different languages and reside on different platforms.

2. Create your languages

It is a significant benefit that XML allows us to specify our markup language for our special purpose. Some examples of XML based languages are Banking Industry Technology Secretariat (BITS), Financial Exchange (IFX), Bank Internet Payment System (BIPS), and many more.

3. Self-descriptive data 

It is very easy to figure out what's going on while we look at an XML document.

4.  XML increases data availability

From XML data sources, different applications can access your data.

Your data can be available to all kinds of "reading machines" with the help of XML.

5. To create new internet languages, XML can be used

By using XML, we can create a lot of new internet languages, such as:

  • For describing available web services, WSDL
  • For handheld devices, WAP and WML as markup languages
  • For news feeds, RSS languages
  • For describing resources and ontology, RDF and OWL
  • For describing multimedia for the web, SMIL

XML in Future Web Development

XML has been developing very quickly since its creation. It is amazing to see how quickly a large number of software vendors have adopted the standard.

It is a strong belief that XML will be as important to the future of the web as HTML has been to the foundation of the web.


So, we have discussed several fundamentals about XML in detail. And now, we hope you are convinced that XML is the best way to move and manipulate structured data. 

Its main focus is ensuring that the data is well organized within descriptive tags (or elements). It is because XML is primarily used for data storage as well as transfer purposes. 

Ultimately, this guide clears that for all data transmission and data manipulation over the web, XML is the future.
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