UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 16)

UGC NET JULY 2018 (Computer Science And Applications Paper-II) (Question 16)

Q16. Coupling is a measure of the strength of the interconnections between software modules. Which of the following are correct statements with respect to modules coupling ?

P : Common coupling occurs when one module controls the flow of another module by passing its information on what to do.

Q: In data coupling the complete data structure is passed from one module to another through parameters.

R: Stamp coupling occurs when modules share a composite data structure and use only part of it.

Code:

(1)  P and Q only                                                                  (2)  P and R only
(3)  Q and R only                                                                  (4)  All P, Q and R only

Answer : (3)  Q and R only 

Reason:

Coupling can be applied to many things such as methods (in object oriented design), systems (in systems engineering) and modules (in any kind of organized system including software systems). Coupling is defined as the extent to which a system, subsystem, method or module connects with (depends on) others. In other words, it measures interdependency. It can be measured for a single module or other entity (the extent to which the module/entity can function or be understood without the use of other modules/entities). 

Types of Coupling

Various authors have described systems for identifying types of coupling. One of the most widely used for software and systems is Myers’ classification, which defines seven levels of coupling, from tightest to loosest:

• Content coupling - modules rely on each others’ internal data or internal organization
• Common coupling - modules share the same global data
• External coupling - modules share an externally imposed data format, communication protocol or device interface
• Control coupling - one module controls the flow of another, such as by passing it a flag or other information
• Stamp coupling - modules share a composite data structure but use different parts of it
• Data coupling - modules share data through parameters, such as in a subroutine call
• Message coupling - modules communicate by passing messages