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ESB As An Application Architecture

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In recent years, there has been a dramatic rise in the popularity of the concept of an Enterprise Service Bus (ESB) over a Service-Oriented Architecture (SOA). This popularity has been especially notable in the context of Enterprise Application Integration (EAI) and related domains where the requirement is for multiple applications to interact, often from multiple companies and distributed across multiple computers. Sonic Software has been one of the most notable evangelists of this concept and arguably provides the best overall infrastructure for implementing this approach.

EAI is a domain in which costs can be extremely high, project size is often extensive, and simple plug and play solutions are sparse and limited. Historically, EAI projects have involved very expensive custom programming to integrate each application with little help from tools. As the number of applications increases, the complexity of the project can become almost astronomical. Products providing pre-developed connections for popular packages have been of limited help since a typical EAI project is likely to involve only one or two such popular packages and the remainder of what can be hundreds of applications still need custom development. Moreover, those tools are typically of a hub and spoke design that can have performance issues with high traffic levels.

EAI projects in earlier years often arose when a large corporation with a large number of separate applications found a need to integrate and interconnect those applications, e.g., as might be driven by the desire to create an integrated customer web portal. While this type of EAI project continues, in recent years, it is also common for the need for integration to be between a company’s own applications and the applications of its vendors and customers, i.e., supply chain integration. The ESB/SOA strategy is, if anything, even more suited to this type of diverse and rapidly changing integration problem than it is to the classic EAI project, particularly since the integration is often structured by emerging standards such as web services.

The availability of a strong software offering like Sonic ESB, which facilitates implementing this integration strategy, can significantly reduce the expense of implementing an EAI project and can even more dramatically reduce the cost of maintenance and future changes as requirements continue to evolve. It is no surprise, therefore, that EAI products, including Sonic, tend to have moderately substantial entry price points since their perceived and real value is high. It is the purpose of this paper to discuss the desirability of a more localized application of the ESB/SOA approach and thus to suggest the need for an alternate licensing strategy when these tools are used as the architectural backbone of a tightly integrated application.

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