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The emergence of service-oriented frameworks results from the evolution of software development and implementation over the last 20 years. Our industry has evolved from monolithic applications and hard-to-manage client/server solutions and has now discovered that the incremental development of components, enabled via a Service Oriented Architecture (SOA), increases the quality of applications, speeds development of new solutions, and addresses the requirements of business stakeholders better.

The concepts embodied in SOA enable an enterprise to integrate its business processes across its lines of business and their supporting information systems. The ability to coordinate the challenges of enterprise-level integration requires an architecture to facilitate the modeling and managing of services spanning information, applications, and people. Through a component-based approach, organizations can build more flexible integration solutions that leverage a common set of core infrastructure services. This solution framework enables the increased agility and adaptability of IT solutions through a more simplified loosely coupled approach. An SOA-based integration foundation provides support for technology co-existence by supporting standards-based design, development, and implementation. This approach provides a scalable infrastructure across existing and future technology assets to provide a solid foundation for the enterprise integration architecture.

Although many integration products claim to support this architectural approach, many products fall short in their ability to provide enterprise integration requirements. This article focuses on the breadth of capabilities required to support the myriad integration styles required for an enterprise-level approach to integration, and discusses the need for a comprehensive Service Oriented Architecture built on open development and runtime standards as the critical component for integration. Through this architectural foundation, enterprises can extend their solutions by combining existing components with new components and by implementing composite applications as integration requirements emerge.

Enterprise Integration Strategy
An enterprise integration strategy requires, at a minimum, the exchange of messages as the foundation of the solution architecture to enable the integration of people, applications/processes, and information. Through this approach, integration solutions can be implemented at departmental levels and easily extended across enterprise boundaries. This approach to integration provides flexibility and a time-to-market advantage for an enterprise and becomes a critical differentiator for success in today's complex and competitive business environment.

Currently a shift is occurring in enterprise integration strategies. Although tactical initiatives continue to be deployed to solve departmental requirements, organizations are defining enterprise integration architecture initiatives based on an SOA approach. This approach requires organizations to identify core integration assets/components and advocates an approach to encourage the reuse and refinement of these assets for integration projects. In this manner, integration across departments can be approached as an enterprise-level initiative that promotes reuse through a standards-based approach to definition, discovery, and invocation.

An enterprise approach to integration is compatible with a more tactical approach to developing departmental/line-of-business integration solutions. In fact, the tactical solutions become assets for the overall integration repository. It's important to provide a governance model that ensures that the development of tactical solutions is done within the context and rules of the enterprise's integration architecture. Without this rigor, enterprises will continue to build departmental integration solutions in isolation and fail to achieve any discernible long-term benefits from integration. Given the rate of change in business and technology, the lack of governance in integration approaches will hinder the ability to effectively and proactively support integration objectives across the enterprise.

Service-Oriented Integration Architectures
Coupled with the need to provide a disciplined approach to integration, it's essential that the enterprise integration architecture leverage the strengths of a service-oriented architecture (SOA). SOA enables the creation of modular composite applications by packaging new as well as existing functions as reusable service components using open and available standards. Service Oriented Architectures are said to provide a "set of business-aligned services that are combined (composed and choreographed) to fulfill business goals...services are manifested as a set of interfaces without any dependencies on the implementation mechanism or location." Loosely coupled component architectures are powerful because they let components act as service consumers and/or providers by exposing interfaces in a standard format across a distributed topology. Composite applications improve the flexibility of IT systems through function isolation, an increased ability to reuse components in multiple contexts, a simpler model for integration, and flexibility in constructing integration processes.

The application of a Service Oriented Approach for integration provides many benefits. It:

• Leverages open standards to surface integration assets as services, fostering the reuse of existing assets and helping avoid vendor lock-in.
• Provides a standard way to represent and interact with integration components (such as maps, processes, discrete transactions/services, or interfaces), providing the flexibility to reuse assets across multiple business process solutions.
• Shifts the integration focus to application assembly rather than implementation details, enabling the efficient implementation of new and modified business solutions.

The SOA approach enables an architectural style consisting of service providers, requestors, and service descriptions enumerated through the familiar publish/find/bind service framework. SOA approaches enable and encourage design principles and patterns encompassing encapsulation, service composition, loose coupling, and reuse.

The service-oriented framework has to be pervasive across all of the aspects of the integration solution. Some current middleware approaches support defining or invoking integration components via SOAP wrappers, but integration architects have to recognize that an SOA approach is far more than just SOAP-based integration. The solution has to support an ongoing evolution of interface definitions (both user-defined and industry-based) as they emerge from standards bodies such as OASIS and OAG. The underlying integration assets of the architecture must conform to an SOA-based approach:

• Service description and definition via a standard interface; for example, WSDL.
• Service invocation/interaction over a standards-based transport/mediation layer.
• Service choreography for orchestrating service interactions; for example, BPEL4WS.
• Service discovery through integrated registry/directory services; for example, UDDI.

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