XML

XML (eXtensible Markup Language), a text-based technology concerned with data description and structure.
Where documents are concerned, computers manage 2 types of file: binary and text.

The main disadvantage of binary files is that they are proprietary, i.e. they can be read and interpreted only by the application which created them.

The disadvantage with text files, on the other hand, is that it is impossible to format the text: for example, you cannot embolden or insert an image file (types of information generally referred to as meta data).

XML combines the advantages of both binary and text formats: on the one hand, it can save formated content (rich text); on the other, it i can be read by any application (it is universally interchangeable).

For this reason, it is regarded as the universal language par excellence.

The first attempt to create a language of this kind was SGML (Standard Generalized Markup Language), way back in 1960, of which XML is a simplification.

Further advantages of XML include:

• the complete separation of content from form
• Multi-platform (it will work with any operating system)
• Meta-language (XML enables you to create derivative languages for managing specific types of data)

The syntax of an XML file is relatively simple:

<employee>
  <first name>Mario</first name<br />  <family name>Rossi</family name>
</employee>

From this example, we see that the basic structure of an XML file can be sub-divided into three components:

• the XML declaration (consisting of 3 elements, of which the first is obligatory, the version)
• a single “root” element, in this case <office worker>
• one or more lines of data marked by opening (e.g. <first name> and closing (e.g. </first name>) tags

One of the most interesting things about this language is that it allows you to create derivative languages to manage any type of data. For example, the XLIFF format enables you to “tag” all the elements to be translated in a document then process it with an editor that can read this format.