Introduction to XML concepts
A way to share knowledge and information

This is a small post on the concept behind XML. This is a non technical article that can be read by anybody interesting in information sharing technologies.

What is XML? It’s a language used to organize information. Any written information can be organized with XML. It can be a documents or an article; it can be a database, etc. The whole concept resides in the fact that XML detach the content of a document with the way to display it on a specific support (on a screen or a printer for example). Then information and information display become two completely separated things. XML is a portability system for data, independent of the display system. This is the equivalent of Java for data description.

By this fact, the exchanges of data between two completely different systems become really ease. The source of information doesn’t need to care of the way the destination will display the information. They only need to care about the way they will ship the information; how they will package it to be understandable by the destination. This concept of information sharing language is used by many systems to communicate one between the other.

We’ll take Amazon as an example. There are 4 agents that share information in the system. There is the client that will buy products on Amazon. There is Amazon, the seller, who needs to buy stock at his supplier. Then the supplier needs to buy his stock to the editors. All these agents need to communicate with information of all kinds. Many types of systems, using different technologies, are implicated in the process of a single transaction. We need to be sure that the destination agent will see the same thing that you see and have the same information. Without a technology like XML it would be virtually impossible to be sure of this fact. But with it, you simply don’t care of the information’s display and you only develop a DTD (Document Type Definition) with the other agents you interact with.

Another example that you use everyday if you are reading this post is RSS feeds. They are XML documents generated by software that need to share some type of information. All RSS feeds have the same DTD. Then when you receive the information, you can display it the way you wish the view it. You can display it on your MyMSN homepage, in your browser. You also can display it on a stand alone feed reader like Omea Reader or FeedDemon.

Finally the main and only concept of XML is really simple and can be written in a single sentence: XML detach the content with his display. This simple sentence of 7 words had changed the way system communicate one between the other.