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Chapter 31. Legacy Integration with the J2EE Architecture

By Steve Steffen and Mark Artiges


As companies embrace the concept of e-business, one of the most challenging tasks they face is reconciling the new business model with the existing legacy systems that they already have in place. Existing enterprise information systems (EISs) must become Web-aware and accessible for any true enterprise-based e-business initiative to have a real chance at being a success. The compelling possibility of real-time collaboration with partners and suppliers that B2B (business to business) e-commerce solutions brings to the table promises to contribute to a company's bottom line. In today's competitive marketplace, where customers crave immediacy along with exceptional service, such integration efforts are not merely nice to have but represent a real necessity. The challenge is providing this synergy across the heterogeneous platforms that typically exist. Failing this, companies run the real risk of falling behind their competition.

A company whose entire business information system is provided by a single vendor would be an oddity. The norm is an in-house assortment of best-of-breed enabling technologies that have evolved over time. Integrating them has always been a sore point. These legacy systems, collectively known as EISs, must be linked to application servers that stand between them, the Internet, and their customers.

Adding to the problem is the fact that when most application servers connect to EIS systems, they do so in a proprietary manner. A huge amount of effort—not to mention cost—is required to develop customized access mechanisms to each of these systems. That is precisely the problem the J2EE Connector Architecture addresses and what this chapter is about. The J2EE Connector Architecture is a specification, contained within the J2EE 1.3 platform, which defines a standard architecture for integrating heterogeneous EISs.

In this chapter, we'll explore this new Sun Microsystems—provided technology and the advantages it affords. We'll look at the overall architecture and its place within Sun's J2EE platform. We'll go over its role as an EAI (enterprise application integration) tool and how it makes possible seamless connectivity in the enterprise.

The J2EE Connector Architecture is a standard heavily based on the notion of a contract existing between a calling party and a receiver. There are system-level contracts, connection management contracts, transaction management contracts, security management contracts, and so on. Each of the contracts will be defined and understood as it exists in relation to the others.

As always, there are security concerns when integrating between systems. We'll learn about the extensive mechanisms that the J2EE Connector Architecture provides in this area as well.

The core of the J2EE Connector Architecture standard is realized in the implementation of what is known as a resource adapter. These software-adapter drivers are where much of the specification is implemented. We'll finish the chapter by spending an ample amount of time on the design, implementation, and deployment of these adapters.

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