What are web services?
Web services are a standard way of creating a self-describing service based on XML that uses the Internet to communicate. What is a service? A service is a program that talks to other programs. The self-describing part of web services is the Web Services Description Language (WSDL). Every web service has a WSDL file that describes its interface. This WSDL file, which is expressed in XML, can be used to generate a program automatically to invoke a web service and get information from it. While communicating with a service can be automated, more study is required to understand the information that must be provided to a web service to get the desired result and to use the information properly. The Universal Description, Discovery, and Integration (UDDI) protocol is a standard for creating a searchable directory of WSDL files so that web services can be located and the WSDL files obtained. You can use UDDI when you are designing or running a program. Web services frequently use the SOAP standard for transferring data back and forth, although it is possible to communicate in other ways as well. OASIS and the W3C, two technology standards bodies, are primarily responsible for the architecture and standardization of web services. The Web Services Interoperability (WS-I) Organization has been developing a series of profiles to further define the standards involved for interoperability. New standards for managing web services and improving reliability and security are under development. You can find a detailed description of web services in Chapter 14.
Enterprise services use web services standards to communicate. So, in an important way, enterprise services are web services. But enterprise services are not just web services. Enterprise services have many additional elements, as described throughout this book. Enterprise services are built with semantic standards as well. They are created to help automate processes, and to perform utility functions related to such automation. Descriptions of enterprise services are stored in the Enterprise Services Repository, which contains not only WSDL files but also models that show how an enterprise service is related to business processes and business objects.