Technology Thoughts

Sunday, February 11, 2007

Against the usage of "logical" and "phisical"

Once upon a time, the terms "logical" and "physical" meant something absolute, at least in specific contexts inside IT. In databases, the physical layer was the actual files and other containers of data, while the logical one was the fields and records immediately on top of them. In networks, the physical layer was the actual wire, and logical referred to the protocol governing the actual bits sent over it.

But nowadays, when there are so many layers in any IT system, the terms physical and logical have lost these absolute position and have only a relative meaning. Logical means just "less detailed", (i.e. abstracting some details out), and physical means just "more detailed" (i.e. with more concrete details). Nowadays, something termed as logical (or physical) in a context is just the physical (or logical) layer of another context.

Thus, when any of these is used without a reference (e.g. "the logical layer" or "a physical diagram"), in many cases the communication is difficulted because the person saying them may have one idea of what they mean, while the others may well have a different one. Then, misunderstanding comes and also time wasted realizing it and trying to sort it out.

Because of this I advocate to either using them only in a relative way (e.g. "this is a logical view of this"), or even better not to use them at all, and using instead other clearer terms.

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