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Video Title: Software Design Approaches
Description: Software Design Approaches
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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In this session, we are going to define
the software design approaches.

So, here we shall discuss two different
types of design approaches.

So, here are two generic approaches for
software designing.

One is the top-down design and another one
is the bottom-up design.

So, let us go through them one by one.

So, at first we are going for this
top-down design.

We know that a system is composed of more
than one subsystems and it contains a

number of different components and further
this subsystems and components may have

their own set
of subsystems and components and

creates hierarchical
structure in the system.

So, software system is the umbrella under
which you are having different components

and subsystems and
those components and subsystems may

have further subsup components and subsup
subsystems.

So, in this way we are getting one
hierarchical structure of the software design.

So, top-down design takes the whole
software system as one entity and then

decomposes it at it to achieve more than
one subsystems or component based on So,

in case of top down design, we shall
consider the software itself as at the

root of the hierarchical structure and
then it will get divided into certain

subsystems and then they will go for
further divisions of them.

Each subsystem and component is then
treated as a system and decomposed further

and this process keeps
on running until the lowest

level of system
in the top down hierarchy is achieved.

So, that means, each and every subsystem
whatever you are getting as a leaf at that

very level,
they will be also treated individually as

a system
and they will go for further bifurcations.

Top down design starts with a generalized
model of the system and keeps on defining

more specific parts of it.

When all the components
are composed the

whole system because
it comes to an existence.

So, it indicates that how far should you
go for sub such subdivisions.

So, it is telling that the systems and
keep on defining more specific parts on it.

So, that is why if we find that this
particular subsystem is consisting of more

than multiple different parts,
more than one parts or multiple different

parts, then you can think of going for
further bifurcations.

And when all the components are composed
the whole system comes into our existence.

So, top down design is more suitable when
the software solution needs to be designed

from the scratch and specific details are
unknown.

In those cases, this top down approach
will be useful.

Now, next one is about bottom-up design.

The bottom-up design model starts with the
most specific and basic components.

So, at first we shall consider that we are
having about basic components.

And it proceeds with composing higher
level of components by using this basic or

lower level components.

So, this basic components will be
comprising with a It keeps creating higher

level components
until the desired system is

not evaluated as the
one single component.

So, this process will be continued until
the basic system that is the main system

whatever we are intending is becoming a
single component.

With each higher level the amount of
abstraction is also getting increased.

Bottom-up design we are continuing with
that.

So, bottom-up strategy is more suitable
when a system needs to be created from

some existing system.

And where the basic primitives can be used
in the newer system.

So, if the system is pre-existing then you
can go for this bottom-up approach.

So, both top-down and bottom-up approaches
are not practical individually.

Instead, a good combination of them
will be

used in our basic software
design approaches.

So, in our software design approaches we
have considered two things.

One is a top-down approach and the one is
the bottom-up approach.

Thanks for watching this video.