XML is one of the main data markup languages, and you have probably heard about it more than once. If you are interested in web development, you need to know what XML is and what its main functions are, among other things.
Believe it or not, these three simple acronyms are one of the most important pillars when designing and developing any website or web application. In this article we will tell you what XML is and how it has been used since the late 90s to store and exchange data.
what is XML?
XML or Extensible Markup Language is a text format used to store and exchange structured data, whether they are documents, configurations, transactions or simply data. It is a markup language that defines the structure and meaning of data.
This data markup language was born as a result of the optimization of the SGML language, an earlier format used for the same purpose. But what is XML for? In concrete terms, XML works as a format with which structured information can be shared between programs, computers and people, mainly through the network.
In addition, this language is present in practically all the technological devices we use, from the computers in a car to certain applications and functions of cell phones. However, the main function of XML, at present, is the transmission of data in the development of web services.
To explain what XML is in a simpler way, we could say that it is a language that was optimized to improve the use of data on the Internet. While HTML is in charge of the visual aspect of the information, XML is in charge of the information itself and the way in which it is structured.
It is also important to note that XML is considered a metalanguage, so it also works to create new languages. An example of this is the XHTML language, which was created from XML code tags.
what is XML for?
Although we have already briefly discussed the functions of the tags in XML documents, we will now explain in more detail what they are used for in each case.
1. Facilitates data exchange
There are two reasons for this: first, because XML data is stored in plain text format, which allows information to be stored and shared between different systems or applications more quickly and easily. Secondly, because if there is something that characterizes XML data, it is that they can be read by different platforms or systems, which, even if they are incompatible, allow developers to easily exchange data between them.
2. Separate HTML data
Thanks to XML, HTML data can be stored in separate XML files, which makes it easier to edit them whenever necessary.
3. Simplifies switching to a new application, system or platform
As mentioned above, XML data is stored in plain text format, making it easier to expand or upgrade to a new information system, browser or platform in the future.
4. useful for creating new data markup languages
In recent years, XML has enabled the creation of different languages, capable of being encoded by different types of reading machines. Thus, we can name RSS (used in news), WAP, WML, XHTML and SMIL, among others.
Differences between XML and HTML
In case you don’t remember, we have emphasized not to confuse XML codes with HTML. Because, although both are markup languages, each has its own functions and different features.
We will begin by explaining what HTML is and what its purposes are.
hTML or Hypertext Markup Language is a document with a set of codes or tags in charge of defining the structure and design of a website. That said, every time a browser reads a document with HTML format and processes each of its elements or “tags”, it is publishing certain information on the screen.
And here it is important to emphasize the first difference with XML language, since while the latter points to the meaning and structure of the data, HTML tags define the appearance of the same; titles, paragraphs, colors, images, among others.
Now, let’s move on to analyze other differences between these two markup languages:
While XML adapts a logical document structure, HTML uses a completely predefined structure through head and body tags.
When dealing with HTML documents or files, certain errors may go unnoticed; very different from the case of XML, where any error may mean serious failures in the system.
Leaving some HTML tags open does not represent any problem, while in the case of XML tags, the tags must always be closed.
Considering the previous point, the same happens with upper and lower case, since in the use of HTML there is no problem, but in XML it can mean a problem.
Advantages of using XML
XML is not one of the most widely used languages for decades by pure chance, its features give it a number of advantages over other languages and make it the preferred language of web developers.
But what are these advantages? To give you a better idea of the benefits of using XML, we will point out some of the main advantages of this language and we will share them with you below:
With XML, programmers have the possibility of creating their own tags for data storage, and they can also use the structure they find most convenient. Of course, for this they must keep the XML syntax rules.
XML is programmed to make data markup with a protocol that facilitates access from different types of platforms. That is, you can store, edit and share XML data from virtually any platform.
With XML it is also easier to search for data, since the data markup with customized tags allows the development of intelligent searches.
These are just some of the benefits of using XML, but the list is much longer. Of these three advantages, perhaps the most important is the customization of tags for data storage.
It is a language that can be adapted and extended to the needs of any type of person. For example, with XML a musician can create tags to classify notes, lyrics and any other type of elements he handles, and a librarian can do the same, but using a tag name adapted to his profession.
how to open XML files?
Now that you know what XML is, it’s time for us to explain how to open and import XML files.
Julian Villamizar, professor of the Python Data Import course, explains that XML files “have tags or labels that allow you to navigate and find information” on the Internet. In other words, thanks to the XML language it is possible to extract data from a web page.
To import XML data you must use different programs, such as Pandas, for example. However, talking about it can take a whole article, so let’s see in more detail how you can open the XML files you imported to your computer.
If you are interested in learning how to import data into XML files, we recommend you explore our catalog of web development and technology courses.
1. Using a web browser
In the XML file saved on your computer, you can right-click on it and choose the “Open with” option. Then, 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. Besides, the browser will be showing you the document in text format in the clearest possible way, using different colors according to the codes. However, the bad thing is that if you do it this way, you will not be able to edit the document.
2. Using a Notepad or Text Editor
This is one of the most common ways to open an XML file. You simply open Notepad if you have Window, or the text editor if you have a Mac, click on the “File” and then “Open”.
Once this is done, you will see the following information:
<? Xml version = “1.0” encoding = “UTF-8”?>
This is a clear indicator 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; taking into account, in addition, 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 so you must be very careful with the edits you make.
3. Using Excel
Although it is not the most common, you can also use Excel to open XML files or documents.
The procedure is simple, you just have to open Excel and then open the XML file, Excel will show you a message asking you to select if you will open the file as an XML table, when you confirm, all the information will be passed to a document that you can easily view and edit.
what is XML Schema?
Maybe more than once you have heard this word and now that we have been talking about XML, surely you have remembered it, wondering what it is or what it means. Here we explain it to you.
XML Schema is a file that contains the rules we have talked about throughout the article. In other words, what XML Schema does is to point out what can and cannot be used in an XML data file.
Generally these types of schema files use the “.xsd” filename extension, as opposed to XML files that use the “.xml extension.”
That said, we could say that schema files or XML Schema files allow different types of programs, systems or applications to validate the different data provided by XML. Likewise, 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.
Thus, when the XML Schema starts checking an XML data file or documents, it is said that it itself has started its validation process, thus obtaining an accurate and completely defined result. That is why using a schema file or XML Schema is essential when carrying out different programming and web development tasks. By using this type of tool it is possible to avoid any damage to the data, since it stops when it detects a problem or failure.
Books to learn more about XML
The best way to understand what XML is and learn how to use this language is by consulting some of the books that talk exclusively about XML. For this reason, we want to share with you a list of books that can help you to know XML language in depth.
It is a small list, only five books, however, we are sure that you will be able to use them to master all XML functions. From XML schemas to the evolution of the language, you will find everything you need to know in these texts.
This book is one of the best books you can use to learn what XML is used for, as it contains 11 chapters and more than 300 pages of XML content.
Its first chapter is a kind of introduction to the XML language, and its main objective is for you to learn what XML is, what are the differences of this language compared to HTML, what procedures you should follow to create XML documents and how you can use the different types of Document Type Definitions (DTD).
XML: A manager’s guide
Having a guide like this in your library can be very useful, because you can consult it every time you are working with XML and need a little help. This work, written by Kevin Dick and published by the publisher Adisson-Wesley, has the purpose of explaining how XML works for the exchange of structured information in intranet, extranet and internet.
The book has a managerial focus, so its explanation of what XML is is aimed at managers and senior business executives. It is an excellent introduction for those who want to know the basics of XML.
XML in a nutshell: A desktop quick reference
Written by Elliote Rusty Harold and Scott Means, this book aims to be a reference for those who work as web developers and want to learn more about the main function of XML. Working with data can sometimes seem complicated, andthe authors of this book do their best to explain how XML facilitates the data storage process.
The book takes a different approach, because instead of explaining what XML is straightforward, it devotes a section to explaining what XML is not. why? Basically because most people confuse XML with other programming languages and expect to do things that are not possible with XML.
The book also has information of interest to those who want to learn how to use the language and get the most out of it.
We hope that our article has helped you to learn what XML is and that all the information we shared with you will allow you to go deeper into the subject. Remember that if in addition to learning about XML