OpenEdge Development: Working with XML - Product ...

Reading and Writing XML with the Document Object Model (DOM)
XML terminology
2–2
The following overview is a refresher of key XML terms and concepts that occur throughout
this manual. It is provided to ensure the manual’s use of familiar XML terminology matches
your own, but it is not a substitute for an XML tutorial. If you are unfamiliar with XML, see
Chapter 1, “Developing with XML in OpenEdge,” for XML learning suggestions.
The Extensible Markup Language (XML) is a data format for structured document interchange
on the Web and other networks. It is hardware-architecture neutral and application independent.
XML documents are composed of storage units called elements that contain either parsed or
unparsed data. Parsed data is made up of characters, some of which form character data, and
some of which form markup. Markup encodes a description of a document’s storage layout and
logical structure.
XML document structure
This section introduces the terms used to describe the parts of an XML document, starting at the
top level and working down to the smallest parts.
XML documents are made up of two parts, called the prolog and the body.
XML prolog
The prolog contains optional information such as the XML version the document conforms to,
information about the character encoding used to encode the contents of the document, and a
reference to either a document type definition (DTD) or XML Schema document which describes
the grammar and vocabulary of the document. The XML Schema document is the more modern
way to describe XML grammar and vocabulary. XML Schemas and DTDs are usually stored in
external documents and the prolog can reference both XML Schemas and DTDs.
This simple example illustrates the prolog:
XML body
The body contains a single top-level element called the root element, which contains all other
elements and other markup information.
This simple example illustrates the prolog and body, where addresses is the root element and
encloses the entire body, or content, of the XML document:
...
...
...