There life cycles in this document. They

There are many different Software
Development Life Cycles  (SDLC) in this
computer science field. Each life cycle is widely used and famous for its
benefits and strong points. However, they also have weak points. Moreover, the
environment and conditions that each life cycle should be used and the purpose
of using is also different from one another. Some famous and widely used life
cycles are as below.

ü  Waterfall

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ü  Spiral

ü  Rapid
Application Development Life Cycle

ü  Dynamic
System Development Life Cycle

ü  Prototyping

ü  V-Model
and etc

Although there are many
development life cycles with its good and bad points, I would like to evaluate
only two life cycles in this document. They are

1.       Spiral
Model and

2.       Dynamic
System Development Life Cycle

Spiral Model

Spiral Model is also known as
Risk-Driven Life Cycle because the whole puts mainly target on the risk
analysis. It is similar to incremental model because the steps of process work
in the form of forwarding based on the previous step. It is a combination of
both prototype development process and linear development process like
waterfall model.

Phases of Spiral Model

There are four phases include in
spiral model. Those phases are called spirals in this model. Those four spirals

1.       Planning

2.       Risk
Analysis Phase

3.       Engineering

4.       Evaluation

Phase 1: Planning

In planning phase, requirements
gathering, cost estimation and resource allocation are processed. Two
requirement specifications named Business Requirement Specification (BRS) and
System Requirement Specification (SRS) are produced for further development in
this phase.

Phase 2: Risk Analysis

.The end product of this risk
analysis phase is a prototype. The strengths and weakness of the projects are
measured. This phase is processed to identify any potential risks and alternate
solutions to it. If any risk is found, the alternate solution is developed and
implemented for that risk.

Phase 3: Engineering

Engineering phase includes
coding, internal testing and deployment includes. This phase mainly targets on
software implementing and testing.

Phase 4: Evaluating

Evaluating Phase is client-side
testing. In this phase, developers show their implemented software or a phase
to the customer and let the customer check. Customers evaluate the software
whether it meets with their requirement and functions well. Then, customers
give feedback to developers and tell whether the phase or product is alright or
not. If there is problem in customer feedback, developers need to repair that
phase again until users satisfied. In general, this phase allows the customers
to evaluate the output of the project to date before the project continues to
the next spiral.

When to use Spiral Model? or Suitable Conditions to use Spiral Model!

Spiral Model should be used when
three or four of the following fact meets with the project.

Æ  When
the project is big and complicated

Æ  When
users do not know properly what they want in the software

Æ  When
cost and risk evaluation is crucial

Æ  When
requirements are complex and scattered

Æ  When
significant changes are expected during and after developing the project

Æ  When
projects are medium high-risk and long-term

Æ  When
projects are on the new product line

Advantages of Spiral Model

ü  Since
spiral model mainly process on risk analysis, potential risks can be avoided.

ü  This
model includes many documentation and therefore it has strong approval and
documentation control.

ü  It
allows requirements changes

ü  It
is cost effective because of high risk management




Dynamic System Development Model (DSDM)

 Dynamic System Development Model is an agile
software development life cycle which is mostly based on the Rapid Application
Development (RAD) methodology. As it is a Rapid Application Development method
that uses incremental prototyping, DSDM is dynamic. The DSDM model mainly
focuses on delivery of the business solution rather than team activities. It is
an organized and efficient life cycle model for software which mainly targets
on delivering business solutions.

While developing
a system using DSDM life cycle, the feasibility study to ensure business sense
of a project before it is developed.  The
DSDM also cooperate and collaborate between all the integrated parties.
Moreover, it uses prototyping heavily to make sure all other parties get a
clear idea of all aspects of the system.

The DSDM has a five-phase life
cycle as follow.

Ø  Feasibility

Ø  Business

Ø  Functional
Model Iteration

Ø  Design
and Build Iteration

Ø  Implementation
or Engineering

There are two stages before and
after the above five stages. They are

Ø  Pre-Project

Ø  Post-Project

Phase 1: Feasibility

In Feasibility
Study, the problem is defined and the technical feasibility of the project is
verified. The team usually researches whether the project can be done within
the constraints of time and resources during this phase. In Feasibility study
phase of DSDM, the following considerations are done.

Æ  Checked
whether the application is suitable for RAD approach or not

Æ  Possibilities
of developing the project

Æ  Considerations
of team’s ability to hand on the project

Æ  Considerations
of problems that can be encountered in the projects

Æ  Assessments
of likely cost of the whole project

Æ  Technical
feasibility of providing software and hardware computer system facility for the

Phase 2: Business

In this phase,
the overall business study of the desired system is performed. The business
requirements are specified and information requirements are identified. After
specifying and identifying various requirements of the system, the basic
architecture framework of the system is prepared.

The team usually researches the
following business aspects of the project.

Æ  Does
it make good business sense?

Æ  Who
are the participants and interested cooperator?

Æ  What
technology will be used to build and deploy it?

Æ  What
is the best work plan?

Æ  What
is needed for building, testing, deploying and supporting the system?

Apart from them, the maintainability level of the system
is also identified here as the system is designed using RAD. So, it needs to be
highly maintainable to set the standards for quality through the development process
as they are based on the incremental development process. Like the feasibility study, the
business study is as short as possible while achieving sufficient understanding
und the requirements.