ITPEC FE Morning April 2018 Question 48

Topic: System Development Technology

In order to increase module independence, the level of module coupling must be low. Which of the following methods of exchanging information between modules has the lowest level of module coupling?

a)Control parameters are passed as arguments in order to control the execution order of modules.b)Only data items that are required for input and output are passed as arguments between modules.c)Relevant module reference data that is defined in a common area.d)Required data is declared externally and shared.

Explanation

Passing only the data items needed for input and output as arguments — this is data coupling, the weakest form of module coupling.

Module coupling, from weakest (best) to strongest:

Data coupling: only the necessary data items are passed as arguments
Stamp coupling: a whole data structure is passed, though only part of it is used
Control coupling: a flag or control parameter is passed that decides what the called module does
External coupling: modules share individual data items declared externally
Common coupling: modules share a common global data area
Content coupling: one module refers to or changes the internals of another

Answer (b)

Why not others:

•(a) — passing control parameters that steer the other module's execution is control coupling
•(c) — referring to data defined in a common area is common coupling, one of the strongest forms
•(d) — sharing data declared externally is external coupling; any module can change it, so the modules depend on each other

Key rule: Coupling gets weaker the less modules know about each other: pass only the data needed, never control flags or shared global data.

System Development Technology · AI-written, may contain errors

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