Software Engineering (2160701)

Question-3b-OR

BE | Semester-6 Winter-2017 | 11/03/2017

Q3) (b)

Compare Coupling and Cohesion. Explain different types of Coupling and its effects on software modules

Cohesion	Coupling
Cohesion is the indication of the relationship within module.	Coupling is the indication of the relationships between modules
Cohesion shows the module’s relative functional strength.	Coupling shows the relative independence among the modules.
Cohesion is Intra – Module Concept.	Coupling is Inter -Module Concept.
While designing you should strive for high cohesion i.e. a cohesive component/ module focus on a single task	While designing you should strive for low coupling i.e. dependency between modules should be less.

Classification of Coupling

Data coupling

Two modules are data coupled, if they communicate through a parameter.
An example is an elementary (primal) data item passed as a parameter between two modules, e.g. an integer, a float, a character, etc.

Stamp coupling

This is a special case (or extension) of data coupling
Two modules (``A'' and ``B'') exhibit stamp coupling if one passes directly to the other a composite data item - such as a record (or structure), array, or (pointer to) a list or tree.
This occurs when Class B is declared as a type for an argument of an operation of ClassA

Control coupling

If data from one module is used to direct the order of instructions execution in another.
An example of control coupling is a flag set in one module and tested in another module.

Common coupling

Two modules are common coupled, if they share data through some global data items.
Common coupling can leads to uncontrolled error propagation and unforeseen side effects when changes are made.

Content coupling

Content coupling occurs when one component secretly modifies data that is internal to another component.
This violets information hiding – a basic design concept
Content coupling exists between two modules, if they share code.

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