Toronto ECE 1770 - Increasing IT Flexibility with IBM WebSphere ESB Software

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ESB solutionsWhite paperIncreasing IT flexibility with IBM WebSphere ESB software.December 2005By Beth Hutchison, Katie Johnson and Marc-Thomas Schmidt, IBM Software GroupIncreasing IT flexibility with IBM WebSphere ESB software.Page 2Increasing IT flexibility with IBM WebSphere ESB software.Page 32 Introduction2 SOA and the ESB4 ESB in the SOA programming model5 WebSphere ESB and WebSphere Integration Developer10 Creating and administering mediations with WebSphere Integration Developer 13 Conclusion15 For more informationContentsIntroduction To encourage business growth while still keeping costs in check, many companies are searching for ways to increase the flexibility and reuse of their existing IT assets. Service oriented architecture (SOA) offers a means to define services that represent a repeatable task, such as “check customer account,” using well-defined, standards-based interfaces. An enterprise service bus (ESB) provides a connectivity infrastructure that you can use to integrate services within an SOA. Together, SOA and an ESB help to reduce the number and complexity of interfaces, enabling you to focus on your core business issues, rather than on maintaining your IT infrastructure.This white paper describes how you can take advantage of the benefits offered by an ESB using IBM WebSphere® Enterprise Service Bus (ESB) software. With this leading-edge product, you can develop and deploy an ESB that enables you to add new services faster and change services more easily, while reusing your existing assets. SOA and the ESBSOA offers a flexible, extensible and composable approach to reusing and extending existing applications and services, as well as constructing new ones. You can implement services using a wide range of technologies, including IBM CICS®, IBM IMS™, Java™ 2 Platform, Enterprise Edition (J2EE), Enterprise JavaBeans (EJB), Java classes, IBM DB2® queries or Microsoft® .Net. In SOA interactions, service providers advertise the capabilities they offer by declaring the interfaces that they implement and their policies governing potential partner interactions. Service requesters can also declare the interfaces they require and the partner interactions they support. Web Services Description Language (WSDL) and other Web services standards provide the vocabulary for these declarations. Service requesters send requests to service providers that offer the capabilities they require, unaware of their implementations. SOA therefore provides an ability to virtualize business functions by isolating service definition and usage from the underlying service implementation.Increasing IT flexibility with IBM WebSphere ESB software.Page 2Increasing IT flexibility with IBM WebSphere ESB software.Page 3An ESB helps you maximize the flexibility of an SOA. Participants in a service interaction are connected to the ESB, rather than directly to one another. When the service requester connects to the ESB, the ESB takes responsibility for delivering its requests, using messages, to a service provider offering the required function and quality of service. The ESB facilitates requester-provider interactions and addresses despite mismatched protocols, interaction patterns or service capabilities. An ESB can also enable or enhance monitoring and management. The ESB provides virtualization and management features that implement and extend the core capabilities of SOA. The ESB virtualizes:• Location and identity. Participants need not know the location or identity of other participants. For example, requesters need not be aware that a request could be serviced by any of several providers; service providers can be added or removed without disruption.• Interaction protocol. Participants need not share the same communication protocol or interaction style. A request expressed as Simple Object Access Protocol (SOAP) over HTTP can be serviced by a provider that only understands SOAP over Java Message Service (JMS).• Interface. Requesters and providers need not agree on a common interface. An ESB reconciles differences by transforming request and response messages into a form expected by the recipient.• Qualities of (interaction) service. Participants or systems administrators declare their quality-of-service requirements, including authorization of requests, encryption and decryption of message contents, automatic auditing of service interactions and how their requests should be routed (optimizing for speed or cost, for example).Interposing the ESB between participants enables you to modulate their interactions through a logical construct called a mediation. Mediations operate on messages in transit between requesters and providers. For complex interactions, mediations can be chained sequentially.Increasing IT flexibility with IBM WebSphere ESB software.Page 4Increasing IT flexibility with IBM WebSphere ESB software.Page 5ESB in the SOA programming modelIBM has introduced a programming model for implementing services and assembling them into solutions. Service Component Architecture (SCA) and Service Data Objects (SDO) provide the underpinnings for this SOA programming model. SCA defines the model for describing service components and offers a way to assemble them into solutions; SDO defines a model for the information exchanged between these components. SCA and SDO are based on Web services standards such as WSDL and XML Schema Definition (XSD) Language, and augment these interoperability standards to define a component model for SOA. This model is discussed in the IBM developerWorks® article, “Introduction to the IBM SOA programming model” available at ibm.com/developerworks/webservices/library/ws-soa-progmodel/.WebSphere ESB software manages the flow of messages between SCA-described interaction end points and enables the quality of interaction these components request. Mediations within the ESB handle routing and logging functions, as well as mismatches between requesters and providers, including protocol or interaction-style mismatches and interface mismatches. In an over-all SCA-based solution, mediations are implemented using a pattern of SCA components that perform a special role, and therefore, have slightly different characteristics than other components that operate at the business level. Mediation components operate on messages exchanged between service end points; in contrast with regular business application components, they are concerned with the


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