Software development lifecycle part2

“Just starting of a software is not enough ,designing , implementing, testing,
delivering and maintenance is also necessary .”
RamanDeep Singh
B.Tech,2nd Year
GTBIT
Software
Development Life Cycle
(SDLC)

Contents For the Presentation
➢Introduction
➢Popular SDLC Models
➢Waterfall Model
➢Iterative Model
➢Spiral Model
➢V-Model

Introduction
Software Life cycle is characterized by undertaking some particular
steps being followed.
These steps are often being defined differently according to the
needs and the complexity of the project.
These steps and how they would be executed collectively
conceptualized the meaning of SDLC model.
Different SDLC models defines different activities performed at
each stage of the software development project in their particular
way.

➢Waterfall Model.
➢Iterative Model.
➢Spiral Model.
➢V-Model.
Popular SDLC Models

Waterfall Model
The waterfall model is a sequential
methodology in which the progress
of the software is seen as flowing
steadily downwards through various
phases.
All the phases are cascaded to each
other such that new phase cannot be
started unless the previous one has
been completed .
Development moves from concept,
through design, implementation,
testing, installation,
troubleshooting, and ends up at
operation and maintenance. Each
phase of development proceeds in
strict order.

Pros and Cons of waterfall model
➢ Pros:
➢ The fixed phases of waterfall model implies discipline in the whole software development
process.
➢ Tangible output at the end of each phase like SRS,SDD,etc gives path to the future development.
➢ The initial two phases gives the formal specification which helps in the efficient knowledge
transfer when team members are dispersed geographically.
➢ Cons:
➢ The most notable con of the waterfall model is that customer do not know the requirements at
one go.
➢ Little opportunity for customer to preview the system .
➢ Designs that look feasible on paper turn out to be expensive or difficult in practice, requiring a re-
design and hence destroying the clear distinctions between phases of the traditional waterfall
model.

Iterative Model
The idea behind the iterative model is to
develop the system through repeated cycles
and in smaller portions of time. In incremental
model the whole requirement is divided into
various builds.
Each subsequent build of the module adds
function to the previous release. The process
continues till the complete system is ready as
per the requirement.
Development begins by specifying and
implementing just part of the software, which
can then be reviewed in order to identify
further requirements. This process is then
repeated, producing a new version of the
software for each cycle of the model.

Pros and Cons of Iterative model
➢ Pros:
➢ Results are obtained early and periodically.
➢ Parallel development can be planned.
➢ Issues, challenges & risks identified from each increment can be utilized/applied to the next
increment.
➢ Cons:
➢ Defining increments may require definition of the complete system.
➢ Not suitable for smaller projects
➢ System architecture or design issues may arise because not all requirements are gathered in the
beginning of the entire life cycle.

Spiral Mode
The idea behind the iterative model is to
develop the system through repeated
cycles and in smaller portions of time. In
incremental model the whole
requirement is divided into various
builds.
Each subsequent build of the module
adds function to the previous release.
The process continues till the complete
system is ready as per the requirement.
Development begins by specifying and
implementing just part of the software,
which can then be reviewed in order to
identify further requirements. This
process is then repeated, producing a new
version of the software for each cycle of
the model.

Pros and Cons of spiral model
➢ Pros:
➢ Risk management is one of the in-built features of the model, which makes it extra attractive compared
to other models.
➢ Issues, challenges & risks identified from each increment can be applied to the next increment.
➢ Project monitoring is very easy and effective. Each phase, as well as each loop, requires a review from
concerned people. This makes the model more transparent.
➢ Development can be divided into smaller parts and more risky parts can be developed earlier which helps
better risk management.
Cons:
➢ Not suitable for small or low risk projects and could be expensive for small projects.
➢ Large number of intermediate stages requires excessive documentation.
➢ Skills required, to evaluate and review project from time to time, need expertise.
➢ Due to client feedback and subsequent customization and modifications carried out in the various stages
of development, reusing the prototypes in future projects becomes difficult.

V Model
The V Model just like the waterfall model
is sequential.
All the processes take place in one after
another in the developments cycle.
The peculiar thing about V model is that
testing of the product is planned in parallel
with the process of the development cycle.
In this model one phase start after previous
one has started.
It is also known for the strong verification
and the validation processes involved in it.
High confidence of customer is required for
choosing the V-Shaped model approach.
Since, no prototypes are produced, there is a
very high risk involved in meeting customer
expectations

Pros and Cons of V model
➢ Pros:
➢ Risk management is one of the in-built features of the model, which makes it extra attractive compared
to other models.
➢ Issues, challenges & risks identified from each increment can be applied to the next increment.
➢ Project monitoring is very easy and effective. Each phase, as well as each loop, requires a review from
concerned people. This makes the model more transparent.
➢ Development can be divided into smaller parts and more risky parts can be developed earlier which helps
better risk management.
Cons:
➢ Not suitable for small or low risk projects and could be expensive for small projects.
➢ Large number of intermediate stages requires excessive documentation.
➢ Skills required, to evaluate and review project from time to time, need expertise.
➢ Due to client feedback and subsequent customization and modifications carried out in the various stages
of development, reusing the prototypes in future projects becomes difficult.

More to come...
Agile Model is now being widely used in the industry because of its
substantial advantages.
(Discussed in next slides to come).

Software development lifecycle part2

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