What is XML in Programming?

XML What is
XML What is

If you are one of those who are interested in the world of programming, surely one or more than once you have wondered what XML is and what it is for. 🤯

And in truth, believe it or not, these three simple acronyms are one of the most important pillars when designing and developing any website or web application … Are you ready to learn more? 🧐 Keep reading and find out here. 

What is XML?

Believe it or not, XML or Extensible Markup Language is much simpler than it seems. It is simply a type of markup language or set of codes (called tags) that define the structure and meaning of the data. Hence, by creating a single format and custom language, it can be used multiple times in different ways on different systems, regardless of the hardware operating system or platform being used. 

It is divided into two parts; prolog and body. The first is administrative metadata, such as the XML document type declaration or the optional processing instruction. On the other hand, the second consists of the structure and content, which we can easily find in simple texts.

And how does it appear on the screen with the naked eye? 🙄

The codes or tags in documents or XML files are easy to recognize because they appear between angle brackets. However, you should not be confused with HTML codes, about which we will explain the difference later. 

What is XML?

Believe it or not, XML or Extensible Markup Language is much simpler than it seems. It is simply a type of markup language or set of codes (called tags) that define the structure and meaning of the data. Hence, by creating a single format and custom language, it can be used multiple times in different ways on different systems, regardless of the hardware operating system or platform being used. 

It is divided into two parts; prolog and body. The first is administrative metadata, such as the XML document type declaration or the optional processing instruction. On the other hand, the second consists of the structure and content, which we can easily find in simple texts.

And how does it appear on the screen with the naked eye? 🙄

The codes or tags in documents or XML files are easy to recognize because they appear between angle brackets. However, you should not be confused with HTML codes, about which we will explain the difference later. 

What is XML for?

Although we have already briefly commented on what are the functions of tags in XML documents, now we will explain in more detail what they are for in each case 😉.

1. Facilitates data exchange: 

And this happens for two reasons. The first, because the XML data is stored in simple text format, which allows storing and sharing the information between different systems or applications in a faster and easier way. The second, because if there is something that characterizes XML data, it is that they can be read by different platforms or systems that, even though they are incompatible, allow developers to easily exchange data between one and another. 

2. Separate the HTML data:

Thanks to XML, HTML data can be stored in separate XML files, making it easy to edit whenever needed. 

3. Simplify the change to a new application, system or platform: 

As we have said before, XML data is stored in plain text format, making future expansion or upgrade to a new information system, browser or platform easier. 

4. Useful for creating new languages ​​on the internet with different types of purposes:

In recent years, XML has allowed the creation of different languages, capable of being encoded by different types of reading machines. Thus, we can name RSS (used in news), WAP and WML, XHTML, SMIL, among others. 

Differences between XML and HTML

In case you don’t remember, we have made a point of not confusing XML codes with HTML. Because, although both are markup languages, each has its own functions and different characteristics. 

We will start by explaining what HTML is and what its purposes are … ✍

 The  HTML or HyperText Markup Language  is a document with a set of codes or labels responsible for defining the structure and design of a website. That said, every time a browser reads a document in HTML format and processes each of its elements or “tags”, it is publishing a certain information on the screen. 

And here it is important to emphasize the first difference with XML, since while the latter points towards the meaning and structure of the data, the HTML tags define the appearance of the same; titles, paragraphs, colors, images, among others. Furthermore, in the text format, HTML tags or tags usually appear twice, at the beginning and at the end. For example, the <body> tag at the beginning and </body> at the end, which indicates the body of a text. 

Now, let’s go on to analyze other differences between these two very particular markup languages: 

  1. While XML adapts a logical structure of the document, HTML uses a completely predefined structure through the head and body tags. 
  2. When it comes to HTML documents or files, certain errors can go unnoticed; very different from the case of XML, where any error can mean serious problems in the system.
  3. Sometimes “play, test” and leave some HTML tag open can be possible and work quite well. However, in the case of XML tags, they need to be always closed. 
  4. Taking into account the previous point, the same happens with upper and lower case letters, since in this case the HTML is not harmed; unlike XML where it can be a problem. 
  5. It is important to bear in mind that XML, being a text-based markup language and having a self-describing structure, can in turn define another markup language without any inconvenience. Very different from the case of HTML, which by not having these characteristics, has a very limited capacity to create another language. 

 Another very important point to keep in mind:

Many times users think that they can replace an HTML document or file with another XML, which turns out to be completely impossible. However, what can be done is to wrap the XML data in HTML tags, to later display it on a  specific web page.

How to open or import one or more XML files?

Now, at this point where you should already know what XML is, we will explain something fundamental when working with this type of markup language, which is how to open or import an XML file without dying in the attempt. 

Because although there are different types of readers of this type of file, there are also other different ways to do it yourself from your computer.  Take a look and tell us what you think… 👀👇

1. Using a web browser

In the XML file saved on your computer, you can right-click and choose the “Open with” option. Next, you will have to decide which browser to use to open the file. 

The good thing about this is that it is a fairly simple and fast method to carry out. In addition, the browser will be showing you the document in text format as clearly as possible, using different colors according to the codes. However, the downside is that if you do it this way, you won’t be able to edit the document. 

2. Using a Notepad or Text Editor 

This is one of the most common ways to open or download an XML file. You just have to open Notepad, if you have Window or the text editor, if you have Mac, click on “File” and then “Open”. 

Once this is done, you will see the following information

<? Xml version = “1.0” encoding = “UTF-8”?>

which will be indicating that the content is already in XML format.

The good thing about this method is that it is simple to perform and also takes a few minutes; also taking into account that you can edit it like any other text. However, as we have said before, any error in an XML file or document can be fatal for the correct performance of the system, application or platform. 

3. Using the Excel program 

While not often recommended, sometimes using Excel to open XML files or documents can also be another viable option. 

You will only have to open Excel, and then open the XML file. Then, you must click on “File” and then “Open”. Next, Excel will show you a message where your first option will be to open as an XML table. There, you will confirm the option and the XML will be converted into a table based on the file’s tags. 

Important data to keep in mind:

An XML file must strictly adhere to a set of highly defined rules that governs XML code. For this reason, if an XML file or document fails to do so, it stops working. Hence, if an XML file cannot be opened or an error message appears, it is most likely that it is not well formed or has been edited incorrectly.

What is the XML schema?

Perhaps more than once you have heard this word and now that we have been talking about XML, you have surely remembered it, wondering what it is or what it means. Here we explain it to you. 👀

The XML Schema is simply a file that contains those rules about which we have already commented. In other words, what XML Schema does is point out what should and should not reside in an XML data file.

Generally these types of schema files use the file name extension “.xsd”, unlike XML files that use the extension “.xml.”

That said, we could say that the schema files or XML Schema allow different types of programs, systems or applications to validate the different data provided by the XML. Furthermore, it provides the framework for the structure of the data, ensuring that it makes sense to the creator or any other type of user. And here it is important to clarify that any program that accepts XML can use the schema file to read, interpret or process the data.