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Video Title: Software Re engineering
Description: Software Re engineering
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 software re-engineering.

So, when we need to update the software to
keep it to the current market and without

impacting its functionality, it is called
software re-engineering.

That means, we want to include some more
features in the software, some extra

functionality in the software,
but without disturbing the software.

Then we can go for the re-engineering of
the software.

And it is a thorough
process where the design of software

is changed and
programs are going to get rewritten.

So, this very diagram is depicting what is
re-engineering.

So, this is our existing software.

So, here we are having this reverse
engineering.

From there, we are going for the
re-structuring and then we are going for

the forward engineering and then we are
having this re-engineered software.

So, let me repeat it once again.

So, here we are having this existing
software which is now running,

but it is lacking some functionality,
some features.

So, they are to be included.

They are to be integrated with this
existing software.

So, what we shall do?

We shall go for the reverse And we shall
go for the restructuring of the software.

And then from this restructuring of the
software, then the forward engineering

will take place, and then we will be going
for re-engineered software.

So, now here you see, here you are
having three

different processes
are required to get executed.

So, we will be discussing three of them in
this order in our current discussion.

Legacy software cannot keep tuning with the
latest technology available in the market.

So, as the hardware become obsolete,
updating of software become a headache.

So, even if the software grows old with
time, the functionality does not.

And that is the reason for which we
require the re-engineering.

So, for example, initially Unix was
developed in assembly language,

but when language C came in the market
into existence, then Unix was

re-engineered in C language.

And because working in assembly language
was difficult.

So, here you can see that the same Unix
which was written in assembly language

code, now
it has got migrated to this C language

and
for which we require re-engineering.

So, other than this, sometimes programmers
notice that few parts of the software need

more maintenance than the other and they
also need re-engineering.

So, these are
the different causes for which we have

mentioned that
why this re-engineering is required.

So, now let us go for the re-engineering
process.

Decide what to re-engineer.

Is it the whole software or the part of
it?

Perform
reverse engineering in order to obtain

the specifications of
the existing software.

So, here we are doing for the reverse
engineering, so that from the existing

software we are going to get our
specification list.

So, restructure program
if required and for example, changing

functions-oriented programs
into object-oriented program.

So, if we require
then you can go for some changing

in the restructuring Re-engineering of
the program.

Then restructure data as required and
apply forward engineering concepts in

order to get the re-engineered software
version.

So, in this
way, these are the different processes

which are taking place
in our re-engineering.

So, there are few important terms used in
software re-engineering.

So, let us go for one by one.

So, at first we are going for reverse
engineering.

So, it is a process to achieve system
specification by thoroughly analyzing,

understanding the existing system.

So, we discussed earlier also.

So, from the existing system, we are
trying to do some understanding,

we are trying to do enough and dedicated
analysis.

So, that we can get the specification
list.

So, this process can be used as reverse
SDLC model.

That is, we try to get
higher abstraction

level by analyzing
the lower abstraction level.

So, program specification from the reverse
engineering.

Now, the
forward engineering will come and the

re-engineered software
version will be obtained.

So, that is a part, that
is a part of the diagram

which you have shown
earlier in this video.

So, now we are going for the reverse
engineering continued.

And an existing system is previously
implemented design, about which we know nothing.

So, and existing system is previously
implemented design, about which we do not

have any documentation, all the
documentation, we do not having any idea.

So, that is why, this is a very
challenging one for us.

So, designers, The sentence,
they do reverse engineering by

looking at the code
and try to get the respective design.

While design in hand, they try to conclude
the specifications also.

Thus going in the reverse from the code to
the system specification and that is the

main purpose of this reverse engineering.

Next one, the next phase whatever we
discussed was program restructuring.

So, it is a process to restructure and
reconstruct the existing software.

And it is all about rearranging the source
code either in the same programming

language from or from one programming
language to another different one as we

had the example of Unix where we had to
migrate from the ASM language code

programming version of the Unix to the new
development was done in C language.

So, restructuring can
have either source code

restructuring and data
restructuring or both.

So, restructuring does not impact the
functionality of the software,

but enhance the reliability and the
maintainability of the software.

And obviously, for which we are going for
the program restructuring.

And program components which cause errors
very frequently can be changed or updated

in the process of the process of
restructuring.

So, whatever the flaws we observed.

So, they are to be restructured here.

The dependability
of software on obsolete hardware platform

can also be removed through this process
of restructuring.

So, now we are having this one that is a
forward engineering.

So, forward engineering is a process of
obtaining desired software from the

specifications in hand which were brought
down by means of reverse engineering.

And it assumes that there was some software
engineering already done in the past.

And forward engineering
is same as a software

engineering process
with only one difference.

So, it is carried out always after reverse
engineering.

So, that is a very important one.

You see, we are having the specifications.

Now, we are
going for the implementation and we are

going to get the
re-engineered version of the software.

But here you see, this is the forward
engineering is there.

So, this forward engineering
will be always will

be executed
after the reverse engineering process.

So, in this way, in our discussion,
we have discussed what is software

re-engineering into details with some
specific diagrams.

Thanks for watching this video.