Introduction to XML

XML stands for eXstensible Mark-up Language. It originates from the more advanced data format SGML. XML is often mentioned together with web technology and HTML but it is important to remember that XML is basically a way to describe and structure data. It can be used in a great variety of applications, not only in web applications.

XML is a self describing data format where data is marked with "tags". Let us look at a simple example:

<?xml version="1.0" encoding="UTF-8"?>

<Ship>

   <Defaults Surface="SPHULL" XMin="FR40" YMin="0" XMax="FR80"/>

   <HullCurve ObjId="SPX951">

      <ByPrincipalPlane X="FR30"/>

   </HullCurve>

</Ship>

"<Ship>" is a tag as well as "<Defaults>". An XML document is organized as a tree structure with one single root element:

In this example "Ship" is the root element. Is has two child elements: "Defaults" and "HullCurve". "HullCurve" has also a child element: "ByPrincipalPlane".