The Architecture Framework
The Architecture Framework Mr. Zachman's original paper described Row Three as the "designer's view", also known as the "model of the information system", meaning that this row had the first seeds of system design. Row Four then was called the "builder's view", which introduced the technology model, and Row Five was the "subcontractor's view", where the subcontractor was the one actually carrying out the work. While agreeing in general with the meaning of each row, your author respectfully takes a different view of the names of the rows and attempts to refine their definitions. "Design" is the set of decisions that determine what a new product is going to look like. Specifically, these decisions take into account the technology that will be used to create it and the relative economics of the technical alternatives. "Architecture", on the other hand, is the set of decisions that determine the shape and characteristics of the desired product. In his original article, Mr. Zachman's analogy is to the field of architecture itself, with the architect creating both the Row Two and the Row Three artifacts. In Mr. Zachman's view, the Row Two artifacts for an architect are the "architect's drawings", representing "a transcription of the owner's perceptual requirements" [Zachman, 1987, p. 278]. This is clearly analogous to the "business owners ' views" of the Framework. The Row Three artifacts are "the translation of the owner's perceptions/requirements into a product"except that they aren't. They do not take into account the contractor's concerns with "technology constraints". Either the tool technology or the process technology may constrain his ability to produce precisely what the architect has designed. In either case, the contractor will have to design a reasonable facsimile which can be produced and yet satisfies these requirements. Commonly called an "elevation", the architect's Row Three drawings describe characteristics of the building, rather than the building itself. They show the appearance of the structure from the outside, as well as its floor plan in detail. In Mr. Zachman's example, the architect describes the building from 16 different points of viewsite plans, electrical system, and so on. Each one of these is describing not the technology to use but rather what is to be accomplished by such technology. The architect is clearly an important player in this process and has a particular point of view. For this reason, Row Three will be described here as the "architect's view". We can still call it a "model of the information system", although this limits the view of the framework to information systems. In other articles, Mr. Zachman points out that the framework is really describing the enterprise as a whole, not just an information system. It is the "logical (automated or nonautomated, systematic) representation of the enterprise" [Zachman, 1999]. A more general term , then, would be to say that the Row Three artifact is a "model of the fundamental characteristics of the business" or, more briefly , a "model of fundamental concepts". In this view, then, Row Four is the "designer's view" and Row Five is the "builder's view". The designer merges technology with the requirements. The builder then actually produces the product. One last issue: In later versions of his Framework (including the one included here as Appendix A), Mr. Zachman calls the business model "conceptual", the "system model "logical", and the technology model "physical". As is described in Chapter 3, these terms were originally used by a committee in the Computer and Business Equipment Manufactures Association (commonly known as ANSI/SPARC), in their description of the "three-schema architecture". This book takes their position that the view held by each person in the business is according to an external schema , the distillation of all these views into an enterprise view is according to a conceptual schema , and the actual way data are stored in the computer is according to an internal schema. Later, people began to refer to the structures of data recognized by specific database management systems as the logical schema. This seems very reasonable, and would suggest that the Business Model is external, the Architect's model is conceptual, the Designer's model is logical, and the Builder's model is physical. None of these discussions of terminology in any way changes the fundamental message of Mr. Zachman's Framework, or even its underlying structure. Because Mr. Zachman is disinclined to change his terminology, however, and modesty prevents your author from referring to what is still 98% Mr. Zachman's work as the "Hay Framework", it will henceforth be referred to here simply as the "Architecture Framework". |
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EAN: 2147483647
Pages: 129