11.5 Web Services

Web services comprise sets of standards that allow programs to invoke software services across IP networks through the exchange of XML messages riding on top of HTTP. HTTP is the communication standard for the Internet. This mirrors the everyday Web, except that instead of human beings, the recipients are application programs. The ubiquity of the Internet, intranets, and wireless networks gives Web services the power to reach almost anyone and enables users to access data mining models anytime from anywhere. The term Web services is actually an abbreviation for web of services, meaning that distributed applications, such as this proposed EVS, will be assembled from a Web of software and databases in the same way that a Web site today is assembled from a disparate number of HTML pages and content from different servers.

Web services are always invoked by means of XML-encoded messages. XML can go anywhere there is an IP network, which nowadays means everywhere, and can be received by any HTTP server. Web services invoke executable programs that are not decided until the XML-encoded message arrives via the IP network. Web services are characterized by late binding just-in-time applications. However, the most distinguishing feature of Web services is that they allow programs, rather than humans, to exchange information and commands in the form of XML messages. This would work for an EVS, in that for example, denial of entry, to board a plane or conduct a transaction at an ATM or other type of terminal, such as an airline ticket dispenser, could be invoked from a centralized data mining server to a machine, rather than to a human inspector.

Tim Berners-Lee, the inventor of the World Wide Web, has embarked on a long-range program called the Semantic Web, which aims to create quasi-intelligent networks through a combination of shared semantics, ontologies, software agents, and service discovery techniques. This EVS would invoke this architecture of distributed intelligence in which a Web service would be used to open up legacy information and data sources from federated databases and process the data through pattern-recognition models populated from IF/THEN rules to authorized users or appliances with access to the Internet, intranet, wireless, or any other proprietary network. Constructing the EVS as a Web service is important because it greatly simplifies the creation and integration of a large-scale system.