Software development model in computer application

Software Development Life Cycle (SDLC)
UNIT 1

Software Development Life Cycle
 Software development life cycle (SDLC) is a
structured process that is used to design,
develop, and test good-quality software. SDLC, or
software development life cycle, is a
methodology that defines the entire procedure of
software development step-by-step. The goal of
the SDLC life cycle model is to deliver high-
quality, maintainable software that meets the
user’s requirements.

 SDLC consists of a precise plan that describes
how to develop, maintain, replace, and enhance
specific software. The life cycle defines a method
for improving the quality of software and the all-
around development process.

 SDLC specifies the task(s) to be performed at
various stages by a software engineer or
developer. It ensures that the end product is able
to meet the customer’s expectations and fits
within the overall budget. Hence, it’s vital for a
software developer to have prior knowledge of
this software development process.

Stages of Software Development Life Cycle

Stage 1
 Planning is a crucial step in everything, just as in
software development. In this same stage,
requirement analysis is also performed by the
developers of the organization. This is attained
from customer inputs, and sales
department/market surveys.
 The information from this analysis forms the
building blocks of a basic project. The quality of
the project is a result of planning. Thus, in this
stage, the basic project is designed with all the
available information.

Stage 2
 In this stage, all the requirements for the target
software are specified. These requirements get
approval from customers, market analysts, and
stakeholders. This is fulfilled by utilizing SRS
(Software Requirement Specification). This is a
sort of document that specifies all those things
that need to be defined and created during the
entire project cycle.

Stage-3: Designing Architecture
 It is a reference for software designers to come
up with the best architecture for the software.
Hence, with the requirements defined in SRS,
multiple designs for the product architecture are
present in the Design Document Specification
(DDS).
 This DDS is assessed by market analysts and
stakeholders. After evaluating all the possible
factors, the most practical and logical design is
chosen for development.

Stage-4: Developing Product
 At this stage, the fundamental development of
the product starts. For this, developers use a
specific programming code as per the design in
the DDS. Hence, it is important for the coders to
follow the protocols set by the association.
Conventional programming tools like compilers,
interpreters, debuggers, etc. are also put into use
at this stage. Some popular languages like C/C++,
Python, Java, etc. are put into use as per the
software regulations

Stage-5: Product Testing and Integration
Software documentation is an essential part of the
software development life cycle. A well-written
document acts as a tool and means to information
repository necessary to know about software
processes, functions, and maintenance.
Documentation also provides information about how
to use the product. Training in an attempt to improve
the current or future employee performance by
increasing an employee’s ability to work through
learning, usually by changing his attitude and
developing his skills and understanding.

Stage-5: Product Testing and Integration

Stage-6: Deployment and Maintenance of
Products
 After detailed testing, the conclusive product is
released in phases as per the organization’s
strategy. Then it is tested in a real industrial
environment. It is important to ensure its smooth
performance. If it performs well, the
organization sends out the product as a whole.
After retrieving beneficial feedback, the
company releases it as it is or with auxiliary
improvements to make it further helpful for the
customers.

Stage-6: Deployment and Maintenance of
Products

Software Development Life Cycle Models
 To this day, we have more than 50 recognized
SDLC models in use. But None of them is perfect,
and each brings its favorable aspects and
disadvantages for a specific software
development project or a team.
Here, we have listed the top five most popular
SDLC models:

Software Development Life Cycle Models
 1. Waterfall Model
 The waterfall model is a software development model
used in the context of large, complex projects,
typically in the field of information technology. It is
characterized by a structured, sequential approach to
project management and software development.
 The waterfall model is useful in situations where the
project requirements are well-defined and the project
goals are clear. It is often used for large-scale projects
with long timelines, where there is little room for
error and the project stakeholders need to have a high
level of confidence in the outcome.

Waterfall Model
 Features of Waterfall Model
1. Sequential Approach
2. Document-Driven
3. Quality Control
4. Rigorous Planning

Importance of Waterfall Model
1. Clarity and Simplicity
2. Clearly Defined Phases
3. Documentation
4. Stability in Requirements
5. Resource Optimization
6. Relevance for Small Projects:

Phases of Waterfall Model
 The Waterfall Model has six phases which are:
1. Requirements
2. Design
3. Development
4. Testing
5. Deployment
6. Maintenance

Advantages of Waterfall Model
 Easy to Understand
 Individual Processing
 Properly Defined
 Clear Milestones
 Properly Documented
 Reinforces Good Habits: The Classical
Waterfall Model reinforces good habits like
define-before-design and design-before-code.

Disadvantages of Waterfall Model
 No Feedback Path
 Difficult to accommodate Change Requests
 No Overlapping of Phases
 Limited Flexibility
 Limited Stakeholder Involvement
 Late Defect Detection
 Lengthy Development Cycle

Agile Model
 The Agile Model was primarily designed to help a
project adapt quickly to change requests. So, the
main aim of the Agile model is to facilitate quick
project completion. To accomplish this task, agility is
required. Agility is achieved by fitting the process to
the project and removing activities that may not be
essential for a specific project. Also, anything that is a
waste of time and effort is avoided. The Agile Model
refers to a group of development processes. These
processes share some basic characteristics but do
have certain subtle differences among themselves.

Steps in the Agile Model
 The agile model is a combination of iterative and
incremental process models. The steps involve in
agile SDLC models are:
 • Requirement gathering
 • Design the Requirements
 • Construction / Iteration
 • Testing / Quality Assurance
 • Deployment
 • Feedback

Principles of the Agile Model
 1. Customer Requirement.
 2. Frequent Delivery
 3. The agile model relies on working software
deployment rather than comprehensive
documentation.
 4. Small team.
 5. Pair programming.

When To Use the Agile Model?
 When frequent modifications need to be made, this method is
implemented.
 When a highly qualified and experienced team is available.
 When a customer is ready to have a meeting with the team all the
time.
 When the project needs to be delivered quickly.
 Projects with few regulatory requirements or not certain
requirements.
 Projects utilizing a less-than-strict current methodology
 Those undertakings where the product proprietor is easily
reachable
 Flexible project schedules and budgets.

Advantages of the Agile Model
 Working through Pair programming produces well-written
compact programs which have fewer errors as compared to
programmers working alone.
 It reduces the total development time of the whole project.
 Agile development emphasizes face-to-face communication
among team members, leading to better collaboration and
understanding of project goals.
 Customer representatives get the idea of updated software
products after each iteration. So, it is easy for him to change
any requirement if needed.
 Agile development puts the customer at the center of the
development process, ensuring that the end product meets
their needs.

Disadvantages of the Agile Model
 The lack of formal documents creates confusion and important
decisions taken during different phases can be misinterpreted
at any time by different team members.
 It is not suitable for handling complex dependencies.
 The agile model depends highly on customer interactions so if
the customer is not clear, then the development team can be
driven in the wrong direction.
 • Agile development models often involve working in short
sprints, which can make it difficult to plan and forecast project
timelines and deliverables. This can lead to delays in the
project and can make it difficult to accurately estimate the costs
and resources needed for the project.

Disadvantages of the Agile Model
 Agile development models require a high degree of
expertise from team members, as they need to be
able to adapt to changing requirements and work
in an iterative environment. This can be
challenging for teams that are not experienced in
agile development practices and can lead to delays
and difficulties in the project.
 Due to the absence of proper documentation,
when the project completes and the developers are
assigned to another project, maintenance of the
developed project can become a problem.

Prototyping Model
 Prototyping is defined as the process of
developing a working replication of a product or
system that has to be engineered. It offers a
small-scale facsimile of the end product and is
used for obtaining customer feedback.

Prototyping Model
 This 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.

Prototyping Model
 In this process model, the system is partially
implemented before or during the analysis phase
thereby allowing the customers to see the product
early in the life cycle. The process starts by
interviewing the customers and developing the
incomplete high-level paper model. This document is
used to build the initial prototype supporting only the
basic functionality as desired by the customer. Once
the customer figures out the problems, the prototype is
further refined to eliminate them. The process
continues until the user approves the prototype and
finds the working model to be satisfactory

Software development model in computer application

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