An RSS News Feed is a prime example of a web service. Our JSS Info Feeds are another example, especially our Glossary Feeds.
CMS Glossary definitions are written using collaborative authoring tools with version control at our companion site CMS Wiki. Definitions are then extracted by a web service (a connector or adapter) that converts them to syndicated information feeds suitable for use on any CMS-related site. They can appear in an iframe, or open a new popup glossary window with a CSS stylesheet to match any site.
Distributed applications put part of their business logic on remote servers where key data can be accessed locally.
For example, a web service provider might publish current stock prices. A web service requestor looking for stock quotes can use UDDI (Universal Description, Discovery and Integration) to retrieve the published interface (the public methods and properties of the remote web service) written in WSDL (Web Service Description Language).
Then it can use XML-RPC(Remote Procedure Call) or SOAP (Simple Object Application Protocol), to exchange information with the web service, most simply using the HTTP protocol, which moves easily through firewalls.
Web Services over HTTP have become wildly successful compared to previous attempts to build distributed applications using complex and platform dependent schemes like CORBA and D-COM.
And the leading industry-standard method for exchanging electronic data between businesses (purchase orders, invoices), called EDI - Electronic Data Interchange - is being replaced rapidly by XML data exchange.