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As a strategy for creating a flexible and agile IT, service-oriented architecture (SOA) has gained considerable momentum in recent years, largely due to the advent of standards-based Web services. There are some powerful business drivers for implementing SOA today:
- IT Agility and Lower Costs
SOAs make IT more responsive to changing business demands and requirements. Reconfiguring business services is simple, fast and low-cost.
- Maximizing Enterprise Application Investments
SOAs are not a rip-and-replace strategy?they wrap and reuse business functions from existing enterprise applications and make them available to a significantly broader audience without change. SOA encourages reuse and avoids unnecessary duplication and reinvention.
- Facilitating New Applications
Web service-based SOAs smooth the development and management of composite applications. Composite applications improve business performance by pulling together information from multiple applications without complicated and time-consuming IT processes.
- Standards?Foundation for the Future
SOAs that use standards-based components and interfaces provide ubiquitous interoperability with all applications and services, making IT more flexible and dramatically simplifying integration.
- This paper discusses how to capitalize on the advantages of SOA by adopting an enterprise foundation for SOA governance and business service lifecycle management. The paper presents a management framework for enterprise architects and acts a guide for implementing an SOA. In addition, it reviews the technical, organizational and process issues involved, and offers recommendations on building an SOA infrastructure.
The Business Value of SOA
SOA is an architectural style for maximizing application interoperability, sharing and reuse in a distributed environment. Service orientation is not a new approach to software development?implementations of objectoriented design, message-oriented middleware, and component-based development have all been guided by many of the same principles. The widespread adoption of Web services standards has reinvigorated the service-oriented approach by providing a universally accepted set of interoperability standards for building, describing, cataloging and managing reusable services. Earlier models required systems to adapt to proprietary software interfaces or to implement complex standards that failed to garner industry support. [Web services technologies, protocols and platforms are discussed in Appendix A.]
As an example, message-oriented middleware provides a basis for an enterprise architecture composed of services designed to interoperate based on well-defined messages transmitted across well-defined message queues. However, this approach requires all systems in the architecture to support the binary message formats and protocols of the messag ing provider, and involves major rework to change providers or even to upgrade between versions of a single product.
In a Web services environment, these same services communicate using standard protocols and formats supported by multiple vendors. Messages are XML documents described using standard XML schemas. Service interfaces are defined using WSDL definitions and implemented using SOAP messaging, with additional functionality provided by the layered WS-* standards. Changing technologies or versions is simplified by the lightweight nature of the standards and the overwhelming adoption of Web services standards by technology vendors and corporate developers.
SOAs have some distinct advantages over other architectures. First, interoperability is an innate characteristic of a service-oriented approach. As described in the example above, SOAs built using Web services support service integration based on universally accepted industry standards. When interoperability is an inherent characteristic of all IT systems and purchased software, the problem of application integration becomes moot. Organizations no longer need to invest inordinate amounts of time and resources on projects that connect applications, freeing the IT team to focus on providing new business functionality.
Second, SOAs make enterprise applications more agile and more responsive to changing business demands. By keeping IT focused on projects that provide business value rather than technical interoperability and upgrades, SOAs allow teams to quickly respond to business initiatives.
Gone are the days where no one is available to respond to business change because they are working on the latest middleware upgrade or adapter projects. Coarse-grained interfaces to functionality allow business analysts and stakeholders to better understand the functionality available to them, and loosely coupled services allow them to freely compose services into applications with minimal IT involvement. Freed from the technical minutiae of your chosen platforms, with an empowered base of business analysts and stakeholders, the IT team can think in terms of business functions and react quickly to changing business demands, requirements or processes.
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