Experiences in Reusing Technical Reference Architectures

ion that we call elaborationpoints. The ability to “drill down” from a contextual view, through logical, to physical architectural constructs is a powerful approach that supports both usability and the widest possible reuse. Currently we are using the terms initial to describe the architectural elaboration point with minimal constraints, logical for the set of designs that include network topology, including the differentiation of clients and servers, andphysical for the stage where hardware architectures and operating systems are defined (though not he numbers of hardware engines required, for example). While the original investment in this project was in support of IBM solution development, it was clear that early value could be demonstrated in IT architecture engagements carried out for our clients by IBM services consultants and professionals. In this context, ESS is not a product for sale or license to our clients. Rather, it provides reusable, proven architectural patterns available to IBM service professionals. The first test of whether the “usability barrier” had been overcome and real value obtained was in 20 or so architecture consulting engagements, carried out in 1997 and the first half of 1998, using early versions of the ESS assets. We have selected three of these, which we believe to be representative and with which the authors were closely associated, to illustrate the use of the assets and draw some conclusions about the value-to both the client and IBM. ESS is most likely to make a real difference in large systems. The three selected engagements were with major organizations in North America-one is a bank and the other two are insurance companies. HARRIS, ROTHWELL, AND LLOYD 99 Two of the organizations have agreed to be identified by name: State Farm Insurance Companies and CT Financial Services Inc. The third organization will remain anonymous. We refer to the organizations as Company A, State Farm, and Canada Trust in the remainder of this paper. It is important to note that all these engagements delivered architectural designs, not code, and that they were related to infrastructure architecture designs, rather than specifically industry-dependent architecture designs (such as core banking). However, call center architectures were included in these en-