Mumbai University > Computer Engineering > Sem6 > Software Engineering

Marks: 10M

Year: May 2015

Cohesion:

• With the help of cohesion the information hiding can be done.
• A cohesive subsystem performs only “one task” in software procedure with little interaction with other modules. In other cohesive subsystem performs only one thing.
• Different types of cohesion:

1. Coincidentally cohesive: The subsystem sin which the set of tasks are related with each other loosely then such subsystems are called coincidentally cohesive.

2. Logically cohesive: A subsystem that performs the tasks that are logically related with each other is called logically cohesive.

3. Temporal cohesive: The subsystem in which the tasks need to be executed in some specific time span is called temporal cohesive.

4. Procedural cohesive: When processing elements of a subsystem are related with one another and must be executed in some specific order, such subsystems is called Procedural cohesive.

5. Communication cohesion: when the processing elements of a subsystem share the data then such subsystem is called communication cohesive.

6. Sequential cohesion: when the output of 1 subsystem is given as input for other subsystem is called Sequential cohesion.

Following fog shows layer cohesion.

The goal is to achieve high cohesion for subsystems in the system.

Coupling:

• Coupling effectively represents how the subsystems can be connected with other subsystem or with the outside world.
• Coupling is a measure of interconnection among subsystems in a program structure.
• Coupling depends on the interface complexity between subsystems.
• The gaol is to strive for the possible coupling among the subsystems in software design.
• The property of good coupling is that it should reduce or avoid change impact and ripple effects.it should also reduce the cost in program changes, testing and maintenance.
• Various type of coupling:

1. Data coupling: The data coupling is possible by parameter passing or data interaction.

2. Control coupling: The modules share related control data in control coupling.

3. Common coupling: In common coupling common data or global data is shared among the modules.

4. Content coupling: Content coupling occurs when one module makes use of data or control information maintained in another module.