The document discusses three software development process models: the Waterfall model, Prototyping model, and Rapid Application Development (RAD) model. The Waterfall model involves dividing the development process into separate sequential phases. The Prototyping model involves iteratively developing prototypes based on customer feedback. The RAD model involves developing components in parallel on a time-boxed basis and assembling them into a working prototype.

1. SOFTWARE DEVELOPMENT
PROCESS MODELS
Instructor: USMAN MURAD (MSCS)

2. Software Development Process
Models
 A process model is chosen based upon the:
nature of the project, application, methods and
tools to be used, and controls and deliverables
that are required. There are many process
models used for software development.

3. Water Fall Model
 In “The Waterfall” approach, the whole
process of software development is divided
into separate phases. The outcome of one
phase acts as the input for the next phase
sequentially. This means that any phase in the
development process begins only if the
previous phase is complete.

4. Advantages & Disadvantages
 Simple and easy to understand and
use
 Easy to manage due to the
inflexibility of the model. Each phase
has specific deliverables and a
review process.
 Phases are processed and
completed one at a time.
 Works well for smaller projects where
requirements are very well
understood.
 Clearly defined stages.
 Well understood milestones.
 Easy to arrange tasks.
 Process and results are well
documented.
 No working software is produced
until late during the life cycle.
 High amounts of risk and
uncertainty.
 Not a good model for complex
and object-oriented projects.
 Poor model for long and ongoing
projects.
 It is difficult to measure progress
within stages.
 Cannot accommodate changing
requirements.
Advantages Disadvantages

5. When to use the waterfall
model:
 Requirements are very well known, clear and
fixed.
 Product definition is stable.
 Technology is understood.
 There are no ambiguous requirements
 Ample resources with required expertise are
available freely
 The project is short

6. Prototyping Model
 The Prototyping Model is used when the customers do not know the
exact project requirements beforehand. In this model, a prototype of
the end product is first developed, tested and refined as per
customer feedback repeatedly till a final acceptable prototype is
achieved which forms the basis for developing the final product.
 In this process model, the system is partially implemented before or
during the analysis phase thereby giving the customers an
opportunity to see the product early in the life cycle. Once the
customer figures out the problems, the prototype is further refined to
eliminate them. The process continues till the user approves the
prototype and finds the working model to be satisfactory.

7. Advantages & Disadvantages
 Customers get a say in the
product early on,
increasing customer satisfaction.
 Missing functionality and errors
are detected easily.
 Prototypes can be reused in
future, more complicated
projects.
 It emphasizes team
communication and flexible
design practices.
 Users have a better
understanding of how the
product works.
 Quicker customer feedback
provides a better idea of
customer needs.
 Prototyping is a slow and time
taking process.
 Some times customers may not
be willing to participate in the
iteration cycle for the longer
time duration.
 Poor documentation because
the requirements of the
customers are changing.
 It is very difficult for software
developers to accommodate all
the changes demanded by the
clients.
 The client may lose interest in
the final product when he or
Advantages Disadvantages

8. When to use Prototype
model:
 Prototype model should be used when the desired
system needs to have a lot of interaction with the end
users.
 Typically, online systems, web interfaces have a very
high amount of interaction with end users, are best
suited for Prototype model. It might take a while for a
system to be built that allows ease of use and needs
minimal training for the end user.
 Prototyping ensures that the end users constantly
work with the system and provide a feedback which is
incorporated in the prototype to result in a useable
system. They are excellent for designing good human
computer interface systems.

9. Rapid Application Development
(RAD) Model
 RAD model is Rapid Application Development
model. In RAD model the components or
functions are developed in parallel as if they
were mini projects. The developments are time
boxed, delivered and then assembled into a
working prototype. This can quickly give the
customer something to see and use and to
provide feedback regarding the delivery and
their requirements.

11. The phases in the RAD Model
 Business modeling: The information flow is
identified between various business functions.
Data modeling: Information gathered from
business modeling is used to define data objects
that are needed for the business.
Process modeling: Data objects defined in data
modeling are converted to achieve the business
information flow to achieve some specific
business objective. Description are identified.
Application generation: Automated tools are
used to convert process models into code and the
actual system.
Testing and turnover: Test new components and
all the interfaces.

12. Advantages & Disadvantages
 Reduced development
time.
 Increases reusability of
components
 Quick initial reviews
occur
 Encourages customer
feedback
 Integration from very
beginning solves a lot
of integration issues.
 Depends on strong team and
individual performances for
identifying business
requirements.
 Only system that can be
modularized can be built using
RAD
 Requires highly skilled
developers/designers.
 High dependency on modeling
skills
 Inapplicable to cheaper projects
as cost of modeling and
automated code generation is
very high.
Advantages Disadvantages

13. When to use RAD model??
 RAD should be used when there is a need to
create a system that can be modularized in 2-3
months of time.
 It should be used if there’s high availability of
designers for modeling and the budget is high
enough to afford their cost along with the cost of
automated code generating tools.
 RAD SDLC model should be chosen only if
resources with high business knowledge are
available and there is a need to produce the
system in a short span of time (2-3 months).