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Jagnesh Chawla([email protected])
Contents :Coupling Highly Coupled Loosely Coupled Uncoupled Types Of Coupling CohesionTypes Of Cohesion
Jagnesh Chawla([email protected])
Coupling Coupling is measure of the
independence of components. Coupling is related to cohesion.It is an indication the strength of
inter connections between the components in a design .
Jagnesh Chawla([email protected])
Highly coupled
These types of systems have interconnections , with program units dependent on each other.
Jagnesh Chawla([email protected])
Loosely coupled
Loosely coupled systems are made up of components which are independent or almost independent.
In this less dependences are available.
Jagnesh Chawla([email protected])
Uncoupled
Uncoupled components have interconnections at all.
No Dependencies
Jagnesh Chawla([email protected])
The range of coupling measures:
Content
coupling
Common
coupling
Control
coupling
Stamp coupling
Data coupling
Uncoupled
Low
Loose
High coupling
Jagnesh Chawla([email protected])
Content coupling:When one component actually
modifies another .Then the modified component is
completely dependent on the modifying one.
Jagnesh Chawla([email protected])
Jagnesh Chawla([email protected])
Common coupling:We can reduce the amount of
coupling somewhat by organizing our design so that data are accessible from a common data store.
ComponentX
Change V1
To zero
ComponentY
Increment V1
ComponentZ
V =V2+A
Global:A1A2A3Variables:V1V2
T T
Jagnesh Chawla([email protected])
Control coupling:When one component passes
parameters to control the activity of another component.
We say that there is control coupling between the two.
Jagnesh Chawla([email protected])
Stamp coupling:
When data structure is used to pass information from one component to another.
Jagnesh Chawla([email protected])
Data coupling:
If only data are passed, the components are connected by data coupling.
Jagnesh Chawla([email protected])
Cohesion:
The cohesion of a component is a measure of the closeness of the relationship between its components.
Jagnesh Chawla([email protected])
Coincidental:
The worst degree of cohesion, coincidental is found in a component whose parts are unrelated to one another.
Jagnesh Chawla([email protected])
Logical cohesion:
It is the next higher level of cohesion , where several logically related functions or data elements are placed in same component.
Jagnesh Chawla([email protected])
Temporal cohesion:
Sometime a component is used to initialize a system or a set variables.
Such a component performs several functions in sequence ,but the functions are related by the timing involved, so its cohesion is temporal.
Jagnesh Chawla([email protected])
Procedurally cohesion:
When function are grouped together in a component just to ensure this order the component is procedurally cohesive.
Jagnesh Chawla([email protected])
Communicationally:
Communicationally cohesion often destroys the modularity and functional independence of the design.
Jagnesh Chawla([email protected])
Sequential cohesion:
If the output from one part of a component is input to the next part the component has sequential cohesion.
