Software Engineering Introduction

Software Engineering Introduction
Dr. Abhineet Anand
Chitkara University
abhineet.anand@chitkara.edu.in
September 2, 2020
Dr. Abhineet Anand (CU) Software Engineering September 2, 2020 1 / 37

1 Software Engineering Introduction
Software Engineering Deﬁnitions
Characteristics of a software
2 Software Engineering - Layered technology
Quality focus
Process
Methods
Tools
3 Software Process Framework
4 Generic Process Model
5 Prescriptive Process Models
The Waterfall Model
Incremental Process model
RAD model

Software Engineering Introduction
Computer software is a product or program code developed by
software engineers.
The applications of computer software are: Telecommunication,
military, medical sciences, online shopping, oﬃce products, IT
industry etc.
A Software consists of data and the related documents.
The software is the key element in all computer based systems and
products.
The main purpose behind software engineering is to give a framework
for building a software with best quality.

Software Engineering Definitions
The establishment and use of sound engineering principles in order to
obtain economical software that is reliable and works efficiently on
real machines.
Software engineering is a systematic and disciplined approach towards
the development of the software operation and maintenance.
Software engineering is an engineering branch associated with the
development of software product using well-defined scientific
principles, methods and procedures.

Characteristics of a software
Software should achieve a good quality in design and meet all the
specifications of the customer.
Software does not wear out i.e. it does not lose the material.
Software should be inherently complex.
Software must be efficient i.e. the ability of the software to use
system resources in an effective and efficient manner.
Software must be integral i.e. it must prevent from unauthorized
access to the software or data.

Software engineering - Layered technology
Software engineering is a fully layered technology.
To develop a software, we need to go from one layer to another.
All these layers are related to each other and each layer demands the
fulﬁllment of the previous layer.
Figure: Software Engineering Layers

Quality focus
The characteristics of good quality software are:
Correctness of the functions required to be performed by the software.
Maintainability of the software.
Integrity i.e. providing security so that the unauthorized user cannot
access information or data.
Usability i.e. the eﬀorts required to use or operate the software.

Process
It is the base layer or foundation layer for the software engineering.
The software process is the key to keep all levels together.
It deﬁnes a framework that includes diﬀerent activities and tasks.
In short, it covers all activities, actions and tasks required to be
carried out for software development.

Methods
The method provides the answers of all ’how-to’ that are asked during
the process.
It provides the technical way to implement the software.
It includes collection of tasks starting from communication,
requirement analysis, analysis and design modelling, program
construction, testing and support.

Methods
The software engineering tool is an automated support for the
software development.
The tools are integrated i.e the information created by one tool can
be used by the other tool.
For example: The Microsoft publisher can be used as a web
designing tool.

Software Process Framework
The process of framework deﬁnes a small set of activities that are
applicable to all types of projects.
The software process framework is a collection of task sets.
Task sets consist of a collection of small work tasks, project
milestones, work productivity and software quality assurance points.
Figure: Software process Framework

Umbrella activities
Software project tracking and control
1 In this activity, the developing team accesses project plan and compares
it with the predeﬁned schedule.
2 If these project plans do not match with the predeﬁned schedule, then
the required actions are taken to maintain the schedule.

Risk management
Risk is an event that may or may not occur.
If the event occurs, then it causes some unwanted outcome. Hence,
proper risk management is required.

Software Quality Assurance (SQA)
SQA is the planned and systematic pattern of activities which are
required to give a guarantee of software quality.
For example, during the software development meetings are
conducted at every stage of development to ﬁnd out the defects and
suggest improvements to produce good quality software.

Formal Technical Reviews (FTR)
FTR is a meeting conducted by the technical staﬀ.
The motive of the meeting is to detect quality problems and suggest
improvements.
The technical person focuses on the quality of the software from the
customer point of view.

Measurement
Measurement consists of the eﬀort required to measure the software.
The software cannot be measured directly. It is measured by direct
and indirect measures.
Direct measures like cost, lines of code, size of software etc.
Indirect measures such as quality of software which is measured by
some other factor. Hence, it is an indirect measure of software.

Software Conﬁguration Management (SCM)
It manages the eﬀect of change throughout the software process.

Reusability management
It deﬁnes the criteria for reuse the product.
The quality of software is good when the components of the software
are developed for certain application and are useful for developing
other applications.

Work product preparation and production
It consists of the activities that are needed to create the documents,
forms, lists, logs and user manuals for developing a software.

Generic Process Model
A software process is a collection of various activities.
There are ﬁve generic process framework activities:
Communication: The software development starts with the
communication between customer and developer.
Planning:It consists of complete estimation, scheduling for project
development and tracking.
Modeling: Modeling consists of complete requirement analysis and the
design of the project like algorithm, ﬂowchart etc.
Construction: Construction consists of code generation and the testing
part.
Deployment: Deployment step consists of delivering the product to the
customer and take feedback from them.

Prescriptive Process Models
The following framework activities are carried out irrespective of the
process model chosen by the organization.
Communication
Planning
Modeling
Construction
Deployment
The name ’prescriptive’ is given because the model prescribes a set of
activities, actions, tasks, quality assurance and change the mechanism
for every project.

Prescriptive Process Models
There are three types of prescriptive process models. They are:
The Waterfall Model
RAD model

The Waterfall Model
The waterfall model is also called as ’Linear sequential model’ or
’Classic life cycle model’.
In this model, each phase is fully completed before the beginning of
the next phase.
This model is used for the small projects.
In this model, feedback is taken after each phase to ensure that the
project is on the right path.
Testing part starts only after the development is complete.
Figure: Waterfall Model

An alternative design
An alternative design for ’linear sequential model’ is as follows:
Figure: The Linear Sequential Model

Advantages of waterfall model
Advantages of waterfall model
The waterfall model is simple and easy to understand, implement, and
use.
All the requirements are known at the beginning of the project, hence
it is easy to manage.
It avoids overlapping of phases because each phase is completed at
once.
This model works for small projects because the requirements are
understood very well.
This model is preferred for those projects where the quality is more
important as compared to the cost of the project.

Disadvantages of the waterfall model
Disadvantages of waterfall model
This model is not good for complex and object oriented projects. It is a
poor model for long projects.
The problems with this model are uncovered, until the software testing.
The amount of risk is high.

The incremental model combines the elements of waterfall model and
they are applied in an iterative fashion.
The first increment in this model is generally a core product.
Each increment builds the product and submits it to the customer for
any suggested modifications.
The next increment implements on the customer’s suggestions and
add additional requirements in the previous increment.
This process is repeated until the product is finished. For example, the
word-processing software is developed using the incremental model.

Advantages of incremental model
Advantages of incremental model
This model is ﬂexible because the cost of development is low and initial
product delivery is faster.
It is easier to test and debug during the smaller iteration.
The working software generates quickly and early during the software
life cycle.
The customers can respond to its functionalities after every increment.

Disadvantages of the incremental model
Disadvantages of the incremental model
The cost of the ﬁnal product may cross the cost estimated initially.
This model requires a very clear and complete planning.
The planning of design is required before the whole system is broken
into small increments.
The demands of customer for the additional functionalities after every
increment causes problem during the system architecture.

RAD model
RAD is a Rapid Application Development model.
Using the RAD model, software product is developed in a short period
of time.
The initial activity starts with the communication between customer
and developer.
Planning depends upon the initial requirements and then the
requirements are divided into groups.
Planning is more important to work together on diﬀerent modules.

The RAD model consist of following phases:
The RAD model consist of following phases:
Business Modeling
Data modeling
The customers can respond to its functionalities after every increment.
Process modeling
Application generation
Testing and turnover

Business Modeling
The cost of the ﬁnal product may cross the cost estimated initially.
This model requires a very clear and complete planning.
The planning of design is required before the whole system is broken
into small increments.
The demands of customer for the additional functionalities after every
increment causes problem during the system architecture.

Data modeling
The information in the business modeling phase is refined into the set
of objects and it is essential for the business.
The attributes of each object are identified and define the relationship
between objects.

Process modeling
The data objects defined in the data modeling phase are changed to
fulfil the information flow to implement the business model.
The process description is created for adding, modifying, deleting or
retrieving a data object.

Application generation
In the application generation phase, the actual system is built.
To construct the software the automated tools are used.

Testing and turnover
The prototypes are independently tested after each iteration so that
the overall testing time is reduced.
The data ﬂow and the interfaces between all the components are are
fully tested. Hence, most of the programming components are already
tested.

RAD Model
Figure: RAD Model

Software Engineering Introduction

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