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Issue 6.3


Loosely coupled systems

Issue: 6.3 (March/April 2008)
Author: Norman Palardy
Author Bio: Norman Palardy has worked with SQL databases since 1992, and has programmed in C, C++, Java, REALbasic, and other languages on a wide variety of platforms. In his 15+ years of IT experience, Norman has developed innovative and award-winning applications for TransCanada Pipelines, Minerva Technologies (now XWave), Zymeta Corporation, and the dining and entertainment industry. He holds a BSc from the University of Calgary in Alberta.
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Article Length (in bytes): 23,335
Starting Page Number: 15
Article Number: 6310
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Wikipedia says coupling [http://en.wikipedia.org/wiki/Coupling_(computer_science) ] is "a relationship in which one module interacts with another module through a stable interface and does not need to be concerned with the other module's internal implementation."

Low coupling is a good thing. The less you rely on undocumented internal behavior of a method, class, or even an entire piece of software, the less coupled your methods and programs are. You should strive to only rely on the output or return values of a method and not on how the method achieves its results. This makes it easier to alter the behavior of a method or class when you find you need to make some change. In an RB program you, as the author, can control this quite readily.

When you have a piece of software that you write that needs to interact with other pieces of software, how do you achieve this same loose coupling? You may want to be able to permit authors to write software in REALbasic and perhaps other languages as well. Somehow you have to make it possible to be able to write "services" in as wide a variety of languages as you can. You may want some pieces written in C, some in C#, some in Java, some in REALbasic, and even others as Unix shell scripts.

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