RSS is one of the simpler forms of what we know as Web Services. This latest article introduces us to RSS, and the many uses it offers for todays applications.
Introduction to RSS - Creating RSS Files (Page 3 of 5 )
The 1.0 proposal differs from the 0.91 format in one main way: It incorporates Resource Description Framework (RDF) elements that allow greater flexibility at the expense of some increased complexity. This proposed specification is more extensible, creating a W3C standard for RSS files that will meet current needs, will be as backwards-compatible as possible, and will be adaptable to future requirements.
Both versions of the specification share the characteristic of being a lightweight format that developers can use for many purposes.
RSS is an XML application. Because of this, all RSS documents begin with the XML 1.0 declaration followed by the RSS document type declaration, as shown in Listing 2.
The first line declares the document to be an XML document. The second line, the DTD declaration, specifies that this XML file is based on the RSS 0.91 document type definition, DTD, at Netscape. Finally, the root element marks the beginning of the RSS file content, all of which goes between the <rss version "0.91"> tag and the </rss> tag.
Web Services 
Building a Generic RSS Class With PHP
