An SOA Starting Point
IBM's Server Express provides an SOA framework
You've probably heard that service-oriented architecture (SOA) is becoming the industry standard for enterprise-integration design. And you likely know that an SOA design provides a flexible and modular approach to expose business tasks as reusable assets called services. However, many people don't realize that IBM* WebSphere* Business Integration Server Express Plus (Server Express) - in addition to its integration and process automation capabilities - provides a framework to support SOA.
I'll provide a high-level description of how Server Express can be used to support an SOA design and how Server Express components can be used out of the box to implement Web services. I'll also outline the product's capabilities as a service router (i.e., Enterprise Service Bus or ESB). It's assumed that you're familiar with SOA-related concepts such as Web services, simple object access protocol (SOAP) and ESB functionality as described in the December 2005 article, "A Blueprint for SOA." Additionally, it's assumed that you're familiar with integration concepts using Server Express as outlined in the May 2006 article, "Integrating Process and Data?" Links to these and other related articles are available in the "References" sidebar.
SOA Implementation Levels
Before describing how Server Express supports an SOA implementation, it helps to define some SOA-related concepts. For starters, I'll term the implementation of a Web service as a "service implementation." The service implementation is logic that implements a particular Web service or set of Web services. In this case, the service-implementation level consists of Server Express components and the applications that participate in the service(s). This level also consists of the Web service enablement method (i.e., the Web services), and, possibly, a gateway.
Additionally, an SOA contains logic to link multiple services, route messages to appropriate services, transform message formats, etc. This service-router implementation corresponds to ESB functionality. This level may also include a universal description, discovery and integration (UDDI) registry and gateway. The service-routing level exists above the service-implementation level and choreographs among an enterprise's services. Server Express can also be used to implement the service-router level.
Figure 1 illustrates these concepts and provides a simple SOA design. The left portion of the figure indicates the service router and implementation levels discussed in the previous paragraph. Note that the two implementation levels outlined here overly simplify SOA design. A more complete description would include much greater detail, like the interactions/transformations between the participating components. For example, when SOAP messages enter the service- implementation level, the Web service transforms them into some other data format.
Server Express Components Support SOA
Server Express provides the functionality necessary to deploy and manage SOA implementations. The key Server Express component for SOA enablement is the Web-Services Connector. Using the connector, along with the Server Express Web Service Definition Language (WSDL) configuration wizard and WSDL Object Discovery Agent (ODA), integration developers can expose collaborations as Web services and enable collaborations to invoke Web services. Leveraging these Server Express functionalities allows you to design core business processing logic without strict considerations for Web service enablement details.
Server Express is an ideal solution for a service implementation; it supports all of the major components at the service-implementation level.
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