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convergent architecture Building model driven J2EE Systems with UML - Hubert R.

Hubert R. convergent architecture Building model driven J2EE Systems with UML - Wiley publishing , 2002. - 289 p.
ISBN: 0-471-10560-0
Download (direct link): convergentarchitecturebu2002.pdf
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From a more modern perspective, the similar use of architectural style can be observed in every mature engineering discipline, from boat design to city planning, from airplane design to automobile production. Prime examples of architectural style in the automobile industry are the roadster, the pickup truck, or the Formula One racing car. In the aerospace industry, we can easily distinguish jets, helicopters, or even Zeppelins as clear representatives of architectural style analogous to the Gothic architecture just described.
A Higher Level of Communication
Not only does the architectural style define how things look—cathedrals, cars, airplanes, and so on—it also often defines other critical design properties such as aerodynamic features, tolerances, and capacities. In addition, it defines how these properties may be achieved dependably with particular materials, tools, and forms (or patterns). Whether it needs to define these aspects, and how it precisely defines them, depends on the particular field. Moreover, where easily distinguishable styles turn up depends on the field. In the automotive industry, for example, we recognize several distinct styles of motor design (Otto, Diesel, or Wankel), each manifesting an intense focus on the intricate performance and thermodynamic properties of internal combustion engines (compression ratios, combustion chambers, fuel mixtures). The consistent evolution of motor performance over the past decades, with little change in their external form, emphasizes that styles also convey hard-to-see design optimizations, not just the definition of external form.
An architectural style expresses the language and design culture that helps stakeholders at all levels to communicate at a higher, more effective level. All mature schools of art, engineering, and science have their own special languages that have evolved over years to help experts express themselves more accurately. If you listen to a group of surgeons conversing during an operation, you probably would not understand much, but they are communicating in a highly effective manner. They are versed in the language of their trade. Such languages are more highly developed, meaning more expressive or more formalized, in some fields than in others. Civil architects have most actively addressed their special language, as indicated by such titles as "The Classical Language of Architecture," "Classical Architecture: The Poetics of Order," or "A Pattern Language" (Alexander 1977), where the grammar and vocabulary of various architectural styles are discussed.
For example, terms accurately describing structures such as arches (archivolt, architrave) and columns (Ionic, Doric, Corinthian) are the words of an architectural
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Convergent Architecture
Chapter 1: IT-Architectural Styel
language. Correspondingly, the organization of structures with respect to one another forms the grammar of the language: The rose window of a Gothic cathedral is always round and is placed above the portal. These words and the grammar are then used to express complete styles—Gothic, Romanesque, Ionic— just as styles of writing, theater, and poetry exist in literature.[2] The style is the next higher level of design expression.
In an IT-architectural style, this translates to, for example, the use of accurate terms for component structures and their relationships to express something the architect considers to be of higher value. In the Convergent Architecture, such structures are its convergent3] organizations, processes, and resources (OPRs) and their relationships. Processes and resources are managed by an organization; a process consumes and produces resources, and so on. Together, and only together, these characteristics lead to the high-level property of convergence in a system based on the Convergent (style) Architecture.
Clearly, there is still much progress to be made concerning the language of IT architecture. Today the common language used by IT designers is very weak. Even though they often use the same words, they are not communicating well. All too often, we experience IT design situations in which people have to explain the terms they use from ground zero. Such meetings can go on forever while making little progress, and everyone has to explain their basic words and grammar to each other every time a new group convenes. Viewpoints then change from one meeting to the other, so the whole frustrating process starts again. It is not just the rare or special term being discussed, but very fundamental concepts such as basic component designs or role definitions. It is as if each designer had entered the meeting having defined his or her own private time system. First, the whole group must discuss and agree on the time system before a simple time plan can be made. Inevitably, each individual will define terms differently. It is no wonder that IT projects are so expensive and high-risk.
The agreement on a language, on a particular style, is often more important than the language itself. No architectural style claims to be the only way to build something, nor does it claim to have found some absolute truth. An architectural style is always a proposition. It is putting a stake in the ground. It is saying that people can build something successfully if they agree to work this way. In other words, there is more than one way to skin a cat, and there will always be several ways to define an architecture. However, this did not keep civil architects from agreeing on architectural styles, whether Gothic, Romanesque, or Renaissance, and then using and refining these styles for hundreds of years. They understood that the major benefits are attained as soon as an organization agrees on an architectural style, not beforehand. By the same token, what large IT organizations need is less philosophical discussion regarding absolute truths and more agreement on an architectural style.
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