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Video Title: Cohesion and Coupling
Description: Cohesion and Coupling
Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm
Lecture By: Mr. Arnab Chakraborty, Tutorials Point India Private Limited
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We are going to discuss a very interesting
topic that is cohesion and coupling.

So, let us discuss on them into more
details and their respective categories.

When a software program is modularized,
the tasks are divided into several modules

based on some characteristics.

In the previous video, we have discussed
modularization.

So, you can watch that one because this
video is a continuation of the previous one.

So, here we can divide
a software, a large

software is
very difficult to handle and deal with.

So, that is why a software can be
considered as a collection of modules.

And these modules can operate
in sequence, can operate in parallel

and each and every module must
have some dedicated purposes.

So, as we know that modules are set
of instructions

put together in order
to achieve some task.

To execute
one task, we can consider one module

which is responsible
for the task execution.

So, they are though considered as a
single entity,

but may refer to each
other on work together.

Always we should try to feel that this
modules are

working in an
having no interdependence in between.

But sometimes one
module can access the other

module can call the
other module for execution.

There are measures by which the quality of
a design of modules and their

introductions among them can be measured.

And these measures are called coupling and
cohesion.

So, how the modules are interacting with
each other and how the statements and

instructions which are residing within one
module.

So, how they are correlated, how they are
related, so that will be handled.

The measurements will be done in coupling
and cohesion.

So, at first we are going to discuss
cohesion, then we shall go for the coupling.

So, cohesion is a measure that defines the
degree of interdependability within

elements of a module.

The greater the cohesion, better is the
program design.

So, what is a cohesion?

We know that a module will be consisting
of multiple number of instructions.

So, how these instructions are having the
interdependability?

So, whether they are very much cohesive or
they are not related to each other.

So, that is the measure of cohesion.

And when a module is having high cohesion,
it indicates that the software design

quality is good enough.

So, there are seven types of cohesion.

So, let first one we are considering that
is co-incidental cohesion.

It is unplanned and random cohesion,
which might be the result of breaking the

programs into smaller modules for the sake
of modularization.

So, because it is unplanned, it may serve
confusion.

So, it may serve confusion to the
programmers and is generally not accepted.

So, in case of coincidental
cohesion, actually

let us suppose we
are having a long code.

We have
divided this code arbitrarily into certain

modules to
implement modularization in our code.

So, the instructions which will be coming
under one module, they are co-incidental.

So, that is why they are not properly very
much related to each other.

So, this sort of cohesion will produce
some confusion in the respective

developers or in the respective coders
mind.

Let us suppose, we are going for the next
cohesion that is the logical cohesion.

When logically
categorized elements are put together

into a module, it is
called a logical cohesion.

So, when some instructions statements are
logically related, and in that case,

if you can put them into one module,
then in that case, we can say that,

that very module is having the logical
cohesion.

So, next one is our temporal cohesion.

When elements of modules are organized
such that, they are processed at a similar

point of time, these things will be known
as the temporal cohesion.

That means, when the elements of a module
are organized in such way that,

they will be executing or they will be
processed at a similar point of time.

So, that is why the name is temporal
cohesion.

Then you can say that, this module is
exerting temporal cohesion.

Next one is our procedural cohesion.

So, procedural cohesion means,
when elements of modules are grouped

together, which
are executed sequentially in order to

perform a task, and
then it is called procedural cohesion.

So, to implement one task in the software,
if you develop one module, that means,

the purpose of the module is that,
if the module gets executed, the task will

get completed, the task is getting
accomplished, then you can say that,

that very module is having procedural
cohesion.

Next one is the communicational cohesion.

So, when elements of modules are grouped
together, which are executed sequentially,

and work on same data, there is an
information.

So, it is called communicational cohesion.

So, whenever instructions are getting
executed, and they are working on the same

set of data, then you can say that,
this particular group of instructions,

so are having this communicational
cohesion.

So, let me repeat it once again.

When elements of module are grouped
together, which are executed sequentially,

one after another, so that is another very
important point.

So, instructions are getting executed
sequentially, linearly, one after another,

and work on the same data set,
that is the information, then you can say

that, this particular module is showing
communicational cohesion.

Next one is the sequential cohesion.

When elements of module are grouped,
because the output of one's element solve

as the input to
another one, and so on, this particular

output of one element will be the input of
the next element.

If it has been, if it is been continued,
then you can say that, this module is

showing sequential cohesion.

The last one is our functional cohesion.

It is considered to be the highest degree
of cohesion, and it is highly expected.

Elements of module in functional cohesion
are grouped, because they all contribute

to a single when defined function.

So, it can be reused again and again.

So, that means, whenever a particular
module is trying to implement one

function, then you can say that,
that module is having functional cohesion.

We know that, a software will have
multiple different functional

requirements, multiple different functions
are to be carried out.

So, if a module, which is dedicated to
execute one function of the software,

then you can say that, the module is
having functional cohesion, and it is the

highly expected, that the module should
have a functional cohesion.

So, in this way, we have discussed all the
cohesion types.

Now, let me discuss coupling.

So, coupling is a measure
that defines a level of

interdependability among the modules
of a program.

So, cohesion was dealing with,
within a single module.

So, how these instructions are getting
related?

So, whether it is coincidental,
temporal, or say procedural.

So, in this way, we are having multiple
different types are there.

So, that is our cohesion.

Now, we are having multiple, say we are
having two modules.

So,
what are the interdependability between

these two,
that will be handled by the coupling.

So, it tells at what level the modules
interfere and interact with each other,

and the lower the coupling, better the
program.

So, always remember this very statement,
that is cohesion higher expected,

and coupling lower between the modules
expected.

So, if you find that there is one software
design, where the modules are having,

modules are highly
cohesive, and modules are

in between modules,
the coupling is very less.

That means, it is a good software design.

So, there are five levels of coupling.

Let me discuss them one by one.

First one is the content coupling.

So, when a module can directly access or
modify or refer to the content of another

module, then it is called content
coupling.

Next one is the common coupling.

When multiple
modules have read and write access to some

global data, it
is called common or global coupling.

When multiple modules can access,
can perform read and write operations on

some set of global data, then you can say
that these two

modules are having
the coupling, known as a common coupling.

Next one is the control coupling,
two modules are called control coupled if

one of them decide the function of the other
module or changes its flow of execution.

So, one module is
deciding Meaning that how the

other module will have
its flow of execution.

So, that is known as our control coupling.

So, let us go for the last but one that is
a stamp coupling.

When multiple modules share the common
data structure and work on different part

of it is called the stamp coupling.

So, when
multiple modules are working on the same

data structure, let it
be the say binary tree.

So, this is a data structure.

So, multiple modules
are working We are back.

We are back.

We are back.

We are back.

We are back.

We are back.

The ccet case case case case case case
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case case case case case Highest cohesion

within a model will be considered as the
best design.

So, in this particular session,
we have discussed what is cohesion,

what is coupling.

These are very important
questions that come in the technical

round, in the
interview and also in our theory exams.

Thanks for watching this video.