Developer's Guide

Table Of Contents
XMLPay Developer’s Guide 9
1
XMLPay Overview
About XML
XML (eXtensible Markup Language) is derived from Standardized General Markup
Language (SGML) and HyperText Markup Language (HTML). In a sense, XML is SGML
“lite”, but XML manages to maintain SGMLs strength as well as HTMLs simplicity. What’s
more, XML can be converted to HTML.
The main advantage of XML is that text can be meaningfully annotated. In XML, markers
identify and tag the text. But the markers themselves have no defined meaning; it is the
applications that define the markers.
XML allows complex transactions to be structured. Client integration is simplified through the
exchange of XML documents. Since XML provides support for digital signatures, documents
from unknown sources can be trusted. In addition, XML can easily produce large documents
such as transaction logs and reports.
Benefits of XML
The main benefits of XML are that it:
z Allows text annotation
z Presents text, data, and content to applications as a structured document
z Facilitates integration of diverse applications
z In addition to these benefits, XML is easy to:
z Read (all text)
z Parse and validate
z Search for content
z Produce
Well-formed XML Document
A well-formed XML document conforms to XML syntax and must have:
z An XML processing instruction at the beginning (prolog)
z A single root element
z Matching (case sensitive) start and end tags for all elements
z All XML elements properly nested
z Attribute values in quotes