SE Unit-1.pptx

School of Computing
Science and Engineering
Program: B.Tech
Course Code: BCSE2355
Course Name: Software Engineering &
Testing Methodologies
Presented by,
Indervati
Assistant Professor,
SCSE

School of Computing Science and Engineering
Course Code : BCSE3003 Course Name: SE & TM
Program Name: B.Tech
Course Outcomes

Course Code : BCSE2355 Course Name: SE
CO NUMBER TITLE
CO1 Understand the key concerns that are common to all
software development processes.
CO2 Select appropriate process models, approaches and
techniques to manage a given software development
process.
CO3 Able to elicit requirements for a software product
and translate these into a documented design.
CO4 Recognize the importance of software reliability and
how we can design dependable software, and what
measures are used.
CO5 Understand the principles and techniques underlying
the process of inspecting and testing software and
making it free of errors and tolerable.
CO6 Understand the Software Quality Assurance (SQA)
architecture and identify Software quality
management standards and procedures

Syllabus
Click Here

• Software Engineering = Software & Engineering.
• The software is a collection of integrated programs.
• Software subsists of carefully-organized instructions and code
written by developers on any of various particular computer
languages.
• Engineering is the application of Scientific and Practical
knowledge to invent, design, build, maintain, and improve
frameworks, processes, etc.
SOFTWARE & ENGINEERING

• Software Engineering is an engineering branch related to the
evolution of software product using well-defined scientific
principles, techniques, and procedures. The result of software
engineering is an effective and reliable software product.
SOFTWARE ENGINEERING

• Software Engineering is an engineering branch related to the
evolution of software product using well-defined scientific
principles, techniques, and procedures. The result of software
engineering is an effective and reliable software product.
• IEEE defines software engineering as: The application of a
systematic, disciplined, quantifiable approach to the
development, operation and maintenance of software

IMPORTANCE OF SOFTWARE ENGINEERING

• Produce reliable and trustworthy systems economically and
quickly
• It is usually cheaper, in the long run, to use software
engineering methods and techniques for professional
software systems
• Failure to use software engineering method leads to higher
costs for testing, quality assurance, and long-term
maintenance.
SOFTWARE ENGINEERING IS IMPORTANT FOR TWO
REASONS:

• Operational Characteristics
• Transition Characteristics
• Revision Characteristics
SOFTWARE CHARECTERSTICS

• Software crisis (Software Failure) refers to the difficulty of
writing correct, understandable, and verifiable computer
programs.
• The roots of the software crisis are complexity, expectations,
and change.
The crisis manifested itself in several ways:
Projects running over-budget, Projects running over-time,
Software was very inefficient, etc.
SOFTWARE CRISIS

1. From Programmers point Of View.
2. From User point Of View
SOFTWARE CRISIS CAN BE CLASSIFIED IN TWO WAYS

1. Problem of Compatibility
2. Problem of Portability
3. Problem of Documentation
4. Problem of Piracy Of Software
5. Problem In Coordination To Work With Other People
6. Problem That Arise During Actual Run Time in The
Organization
7. Problem of Maintenance In Proper Manner.
FROM PROGRAMMERS POINT OF VIEW

1. How To Choose Software From Total Market Availability
2. How To Ensure That Which Software Is Compatible With There
Hardware.
3. Problem Of Viruses.
4. Problems Of Software Bugs.
5. Certain Software Runs On Specific Os.
6. Problem Of Different Versions Of Software.
7. Security Problem For Protected Data In Software
FROM USER POINT OF VIEW

Software Process
• The process that deals with the technical and management
issues of software development is called software process.
• enables rational and timely development of computer
software.
SOFTWARE ENGINEERING PROCESSES

Software Process
• Identify new problems and solutions in software production.
• Study new systematic methods, principles, approaches for
system analysis, design, implementation, testing and
maintenance.
• Provide new ways to control, manage, and monitor software
process.
• Build new software tools and environment to support
software engineering.
WHY SOFTWARE ENGINEERING PROCESSES ?

• To increase software productivity and quality.
• To effectively control software schedule and planning.
• To reduce the cost of software development.
• To meet the customers’ needs and requirements.
• To enhance the conduction of software engineering process.
• To improve the current software engineering practice.
• To support the engineers’ activities in a systematic and
efficient manner.
MAJOR GOALS

Programming vs. Software Engineering
• Programming: The process of translating a problem from its
physical environment into a language that a computer can
understand and obey.
• Software Engineering: “The establishment and use of sound
engineering principles in order to obtain economically
software that is reliable and works efficiently on real
machines.”
SIMILARITIES AND DIFFERENCES FROM CONVENTIONAL
ENGINEERING PROCESSES

Computer Science
• Theory
• Fundamentals
Software Engineering
• The practicalities of developing
• Delivering useful software
SIMILARITIES AND DIFFERENCES FROM CONVENTIONAL
ENGINEERING PROCESSES

• Cost
• Schedule
• Quality
SOFTWARE QUALITY ATTRIBUTES

• Functionality: The Capability to provide functions which meet
stated and implied needs when the software is used.
• Reliability: The capability to maintain a specified level of
performance.
• Usability: The capability to be understood, learned, and used.
• Efficiency: The capability to provide appropriate performance
relative to the amount of resources used.
• Maintainability: The capability to be modified for the purpose
of making corrections, improvements etc.
• Portability: The capability of the software to be work properly
in different environment without applying any action
SOFTWARE QUALITY

SOFTWARE DEVELOPMENT LIFE CYCLE
• SDLC provides a series of
steps to be followed to
design and develop a
software product efficiently.
SDLC framework includes
the following steps:

COMMUNICATION & REQUIREMENT GATHERING
• Communication
– User initiates the request for a desired software product.
– He contacts the service provider and tries to negotiate the terms.
– He submits his request to the service providing organization in writing.
• Requirement Gathering
– Studying the existing or obsolete system and software.
– Conducting interviews of users and developers.
– Referring to the database or
– Collecting answers from the questionnaires.

FEASIBILITY STUDY & SYSTEM ANALYSIS
• Feasibility Study
– At this step the team analyzes if a software can be made to fulfill all
requirements of the user.
– The project is financially, practically and technologically feasible for
the organization to take up.
• System Analysis
– The developers decide a roadmap of their plan and try to bring up the
best software model suitable for the project.
– Understanding of software product limitations, learning system
related problems or changes.
– Analyzes the scope of the project and plans the schedule and
resources.

SYSTEM DESIGN & CODING
• Software Design
– logical design and physical design.
– produce meta-data and data dictionaries, logical diagrams, data-flow
diagrams and in some cases pseudo codes.
• Coding
– Known as programming phase.
– Writing program code in the suitable programming language.
– Developing error-free executable programs efficiently.

TESTING & INTEGRATION
• Testing
– Testing is conducted by testing experts.
– Various levels of code such as module testing, program testing,
product testing, in-house testing and testing the product at user’s end.
– Early discovery of errors and their remedy is the key to reliable
software.
• Integration
– Software may need to be integrated with the libraries, databases and
other programs.

IMPLEMENTATION & OPERATION AND MAINTENANCE
• Implementation
– Installing the software on user machines.
– Software is tested for portability and adaptability and integration
related issues are solved during implementation.
• Operation and Maintenance
– Confirms the software operation in terms of more efficiency and less
errors.
– Users are trained on, or aided with the documentation on how to
operate the software.
– Software is maintained timely by updating the code according to the
changes taking place in user end environment or technology
– face challenges from hidden bugs and real-world unidentified
problems.

DISPOSITION
• Disposition
– May decline on the performance front.
– Go completely obsolete or may need intense upgradation.
– This plan will include a statement of why the application is no longer
supported, a description of replacement/upgrade, a list of
tasks/activities (transition plan) with estimated dates of completion

SDLC MODELS
• Waterfall Model
• Prototype Model
• Spiral Model
• Evolutionary Development Models
• Iterative Enhancement Models.

WATERFALL MODEL
• Referred to as a linear-sequential life cycle model.
• Each phase must be completed before the next phase can
begin and there is no overlapping in the phases.

WATERFALL MODEL

WATERFALL MODEL
Requirement Gathering and analysis
• All possible requirements of the system to be developed are
captured in this phase and documented in a requirement
specification document.
System Design
• Specifying hardware and system
• Defines the overall system architecture.

WATERFALL MODEL
• Implementation − With inputs from the system design, the
system is first developed in small programs called units, which
are integrated in the next phase. Each unit is developed and
tested for its functionality, which is referred to as Unit Testing.
• Integration and Testing − All the units developed in the
implementation phase are integrated into a system after
testing of each unit. Post integration the entire system is
tested for any faults and failures.

WATERFALL MODEL
• Deployment of system − Once the functional and non-
functional testing is done; the product is deployed in the
customer environment or released into the market.
• Maintenance − There are some issues which come up in the
client environment. To fix those issues, patches are released.
Also to enhance the product some better versions are
released. Maintenance is done to deliver these changes in the
customer environment.

WATERFALL MODEL
Advantages of waterfall model
• This model is simple and easy to understand and use.
• It is easy to manage due to the rigidity of the model – each
phase has specific deliverables and a review process.
• In this model phases are processed and completed one at a
time. Phases do not overlap.
• Waterfall model works well for smaller projects where
requirements are very well understood.

WATERFALL MODEL
Disadvantages of waterfall model
• Once an application is in the testing stage, it is very difficult to
go back and change
• something that was not well-thought out in the concept
stage.
• 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.
• Not suitable for the projects where requirements are at a
moderate to high risk of changing.

WATERFALL MODEL
When to use the waterfall model
• This model is used only when the 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.

PROTOTYPE MODEL
• A prototyping model suggest that before carrying out the
development of the actual software, a working prototype of
the system should be built.
• A prototype is a toy implementation of the system.
• Prototype is a working model of software with some limited
functionality.
• Prototyping is used to allow the users evaluate the developer
proposals and try them out before implementation.
• By using this prototype, customer can understand the
requirements of desired system and also the customer can get
an “actual feel” of the system. It is an attractive idea for
complex and bigger systems.

PROTOTYPE MODEL

PROTOTYPE MODEL
Requirements gathering and Analysis
A prototype model begins with requirements analysis, and the
requirements of the system are define in detail. The user is
interviewed in order to know the requirements of the system.
Quick design
When requirements are known, a quick design for the system is
created. It is not a detailed design , it includes the important
aspects of the system, which gives an idea of the system to the
user.

PROTOTYPE MODEL
Build prototype:
Information gathering from quick design is modified to form a
prototype .It represents a ‘rough’ design of the required system.
Customer evaluation of prototype:
The build prototype is presented to the customer for his/her
evaluation.

PROTOTYPE MODEL
Prototype refinement:
Once the user evaluate the prototype, it is refined according to
the requirements . When the user is satisfied to the developed
prototype , a final system is developed based on the final
prototype , which is developed by the iterative method means
we design the system according to the final prototype , after that
implement , test the product to find the error and at last we
maintain the system.

PROTOTYPE MODEL
Advantages
• User early in the process , enabling early assessment and
increasing the user confidence
• Better implementation of the requirements.
• It helps in reducing the risk associated to the project.
• Improving communication between developer and user

PROTOTYPE MODEL
Dis-Advantages
• If the user is not satisfied with developed prototype, then a
new prototype is developed .
• The developer loses focus of the real purpose of the
prototype and compromises on the quality of the product.

ITERATIVE MODEL

Low Level Design:
Modularization,
Design Structure Charts,
Pseudo Codes,
TOPICS TO BE COVERED

• Modularization is a technique to divide a software system into
multiple discrete and independent modules, which are
expected to be capable of carrying out task(s) independently.
• Designers tend to design modules such that they can be
executed and/or compiled separately and independently.
MODULARIZATION

• Smaller components are easier to maintain
• Program can be divided based on functional aspects
• Desired level of abstraction can be brought in the program
• Components with high cohesion can be re-used again
• Concurrent execution can be made possible
• Desired from security aspect
ADVANTAGE OF MODULARIZATION

• Structure Chart represent hierarchical structure of modules.
• It breaks down the entire system into lowest functional
modules, describe functions and sub-functions of each
module of a system to a greater detail.
STRUCTURE CHART

• Module
It represents the process or task of the system. It is of three
types.
– Control Module
A control module branches to more than one sub module.
– Sub Module
Sub Module is a module which is the part (Child) of
another module.
– Library Module
Library Module are reusable and invokable from any
module.
SYMBOLS USED IN CONSTRUCTION OF STRUCTURED CHART

MODULE

• It represents that control module can select any of the sub
module on the basis of some condition.
CONDITIONAL CALL

• It represents the repetitive execution of module by the sub
module.
• A curved arrow represents loop in the module.
LOOP (REPETITIVE CALL OF MODULE)

• It represents the flow of data between the modules. It is
represented by directed arrow with empty circle at the end.
DATA FLOW

• Physical Storage is that where all the information are to be
stored.
PHYSICAL STORAGE

STRUCTURE CHART FOR AN EMAIL SERVER

• It is a methodology that allows the programmer to represent
the implementation of an algorithm.
• cooked up representation of an algorithm.
• These include while, do, for, if, switch. Examples below will
illustrate this notion
PSEUDO CODE

If student's grade is greater than or equal to 60
Print "passed"
else
Print "failed"
PSEUDO CODE EXAMPLE 1

Pseudocode
While the power of 2 is not larger than 1000
keep on getting the values of the power of 2.
C++ statement
int product = 2;
while ( product <= 1000 )
product = 2 * product;
PSEUDO CODE EXAMPLE 2

1. Software Engineering: A practitioner’s Approach,
Roger S Pressman, Sixth Edition. McGraw-Hill
International Edition, 2005.
2. Software Engineering: Ian Summerville, Seventh
Edition, Pearson Education, 2004.
3. Daniel Galin, “Software Quality Assurance”, Pearson
Publication, 2009.
REFERENCES

SE Unit-1.pptx

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