A common scenario for using Web services is in the creation of business-to-business (B2B) systems where you must expose some business functions as services using Web technologies that users access from outside your network boundary. Typically, you use HTTP (port 80) or HTTPS (port 443) to pass messages through firewalls and DMZs because proprietary protocols ports are disabled by default.
Web services let you integrate independent functions within the enterprise while supporting distributed transactions. I'll explain how to implement this kind of functionality, covering how to publish a Procedural Language/SQL (PL/SQL) procedure in an Oracle Database as a Web service, as well as how to consume it from a Web service client in Windows Communication Foundation (WCF).
