The abbreviation XML refers to the Extensible Markup Language, which is used for the representation of hierarchically structured data. Data in text file format. XML is also used for the exchange of data between computer systems that are independent of platforms and implementations.
The characteristics of XML
The XML specification defines a meta language, on the basis of which, in turn, application-specific languages are determined by content and structural restrictions. The restrictions are expressed using XML or DTD schemas. Examples of XML languages include MathML, RSS, GraphML, XAML, or GPX, as well as the XML schema itself. An XML document is composed of text characters in UTF-8 encoding. You can view and edit XML in any editor that supports UTF-8. If an XML document is to contain binary data, this data must be encoded as text, for which different types of encoding can be used. With regard to XML documents, the element is considered the most important structural unit, with elements containing both text and other elements as content. The name of an XML element can be freely defined in XML documents without DTD. In XML documents with DTD, the element names must be displayed in the DTD and the element must be in a position that is permitted in the structure tree. The content of each element is defined in the DTD. The elements are regarded as information carriers of an XML document,
The history of XML
XML arose from the fact that the programming language HTML has reached a certain point of exhaustion.
Although HTML has achieved a lot, its limitations became apparent very early on in the beginning of the Internet and it became clear relatively quickly that a language was needed that would offer the possibility of defining any tags universally. SGML was a longer, universal document language, from which HTML was also derived, but it turned out to be too complicated for the web. With XML a very light document language was developed, which is arbitrarily extendable. XML is used to define own tags in an uncomplicated way, whereby the appearance is fixed, in contrast to the meaning, which is not defined. A tag either stands on its own or encloses an area, whereby tags have one or more parameters or none at all. The parameters receive values which are enclosed and assigned with certain commands. The tags can be nested within each other, thus structuring the data hierarchically.
The advantages of XML
Basically, XML can be used for any kind of description, storage or exchange of data. The advantages of XML lie in the wide distribution and the associated low learning effort, in the popularity and the ease of use. Readability for machine and man. In comparison to an own binary format, which is compact, the larger memory requirements and the sometimes slower processing are among the disadvantages. However, both aspects hardly play a role nowadays, so that the advantages outweigh the disadvantages and XML has accordingly been able to establish itself in numerous areas.
Various fields of application
Besides the use of new tags for writing documents, the different areas of application include
that different output formats can be generated from the same XML page and that the creation of websites can be done with separation of design and programming.
