Implement the components of an SOA with Web services
By Brian Schaffner, Builder.com
Tuesday, November 11, 2003 12:00 PM
I previously discussed how to build a service oriented architecture (SOA) that
aligns with your business processes. Now, I'll elaborate on the SOA
architecture and describe how to implement the components. Using Web services
technology, I’ll explain how to create the design for implementing a service
agency, service provider, and service requestor.Tuesday, November 11, 2003 12:00 PM
Implementing services with Web technology
Web technology has matured to the point that it can provide a rich set of tools for delivering services. Web services technology is built largely on other technologies, specifically XML and HTTP. Services are commonly delivered as wrappers for existing applications. Figure A illustrates the relationship between the various components of a Web service and how they work together to deliver a service architecture.
| Figure A |
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| Web services implementation of an SOA |
In the above figure, you can see that UDDI provides the discovery agency, that Web and application servers deliver the service provider, and that applications act as the service requestor—fulfilling the SOA model.
Abstracting application functionality in the service provider
Web services essentially provide a service wrapper that abstracts functionality across one or more applications. Some Web services may provide functionality from a single application while others provide an aggregate interface for multiple applications. The mapping of applications to services allows applications and technology to align with the business processes. Figure B shows an example of how application functionality is mapped to a service implementation.
| Figure B |
 |
| Example of mapping application functionality to service |
Component architectures, like Enterprise Java Beans (EJBs), provide an encapsulation of services that can be delivered in an application server environment. A Web server provides the HTTP network transport for accessing the service. The application server hosts the SOAP interface and the object components that make up the service. The object components provide the business service layer above the applications.
The end result is that the Web service abstracts underlying applications to provide richly defined services. These services then map into well-defined business processes. Creating an abstraction layer above applications enables them to deliver functionality in a more meaningful way—defined as business services.
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