Web services overview
On the client side, no additional software is required. On the server side, a Web server and servlet engine are required.
The definition of the message format travels with the message; no external metadata repositories or code generation tools are required.
Simple Web services can be aggregated using workflow techniques or by calling lower layer Web services.
Common Web services:
- theatre review articles
- weather reports
- credit checks
- stock quotations
- travel advisories
- airline travel reservations
Categories of Web services
Web services categories:
- Business information
A business shares information with consumers or other businesses. In this case, the business is using Web services to expand its scope. Examples of business informational Web services are news streams, weather reports, or stock quotations.
- Business integration
A business provides transactional, "for fee" services to its customers. In this case, the business becomes part of a global network of value-added suppliers that can be used to conduct commerce. Examples of business integration Web services include bid and auction e-marketplaces, reservation systems, and credit checking.
- Business process externalization
A business differentiates itself from its competition through the creation of a global value chain. In this case, the business uses Web services to dynamically integrate its processes. An example of business process externalization Web services is the associations between different companies to combine manufacturing, assembly, wholesale distribution, and retail sales of a particular product.
Service roles and interactions
A network component roles:
- service provider
- service broker
- service client
- Service providers create and deploy their Web services and can publish the availability of their WSDL-described services through a service registry, such as a UDDI Business Registry.
- Service brokers register and categorize published services and provide search services. For example, UDDI acts as a service broker for WSDL-described Web services.
- Service clients use broker services such as the UDDI Business Registry to discover a needed WSDL-described service and then bind to and call the service provider.
Binding involves establishing all environmental prerequisites that are necessary to successfully complete the services. Examples of environmental prerequisites include security, transaction monitoring, and HTTP availability.
For more information on Web services, refer to www.ibm.com/developerworks/webservices
Links
- Web services standards
One of the key attributes of Internet standards is that they focus on protocols and not on implementations. The Internet is composed of heterogeneous technologies that successfully interoperate through shared protocols. This prevents individual vendors from imposing a standard on the Internet. Open Source software development plays a crucial role in preserving the interoperability of vendor implementations of standards. - Creating top-down Web services
Web services can be created using two methods: top-down development and bottom-up development. Top-down Web services development involves creating a Web service from a WSDL file. - Creating bottom-up Web services
Web services can be created using two methods: top-down development and bottom-up development. Bottom-up Web services development involves creating a Web service from a Java bean or enterprise bean.
Related Concepts
Tools for Web services development
Related Tasks