Software Engineering Fundamentals Svetlin Nakov774

7/28/2019 Software Engineering Fundamentals Svetlin Nakov774

1/49

Software Engineering

Fundamentals

Svetlin NakovNational Academy for

Software Development

academy.devbg.org
http://academy.devbg.org/http://academy.devbg.org/http://academy.devbg.org/http://academy.devbg.org/


2/49

Agenda

1. Software engineering overview Requirements

Design

Construction Testing

Project management

2. Development methodologies overview The Waterfall development process

Heavyweight methodologies

Agile methodologies and XP


3/49

About The Speaker

Svetlin Nakov Founder and Chairman of BASD

Director training and consulting

activities, National Academy forSoftware Development (NASD)

15 years of developer experience

8 year as a professional software

engineer, trainer and consultant

Author of 4 books, 20 articles, and50 seminar lectures

Lecturer in Sofia University and NBU
http://www.devbg.org/http://www.nakov.com/books/signatures/http://www.devbg.org/dotnetbook/http://www.nakov.com/books/inetjava/


4/49


Requirements, Design,

Construction, Testing


5/49

What is SoftwareEngineering?

Software engineeringis the

application of a systematic,

disciplined, quantifiable approachto the development, operation,

and maintenance of software

Defini t ion by IEEE


6/49


Software engineering is: An engineering discipline that provides

knowledge, tools, and methods for:

Defining software requirements

Performing software design

Software construction

Software testing

Software maintenance tasks

Software project management


7/49

Software DevelopmentActivities

Software development always includesthe following activities (to some extent):

Requirements analysis

Design

Construction

Testing (sometimes)

These activities do not follow strictly oneafter another!

Often overlap and interact

SoftwareProject

Management


8/49

Software Requirements

Functional, Non-functional

Requirements, SRS


9/49


Software requ irementsdefine thefunctionality of the system

Answer the question "what?", not

"how?"

Define constraints on the system

Two kinds of requirements

Funct ionalrequirements

Non-funct ionalrequirements


10/49

Requirements Analysis

Requ irements analysisstarts from avision about the system

Customers don't know what they need!

Requirements come roughly and arespecified and extended iteratively

Prototypingis often used, especially for

the user interface

The outcome is the Software

Requirements Specification (SRS)


11/49

Software RequirementsSpecification (SRS)

The Software Requ irementsSpecif icat ion (SRS)is a formalrequirements document

It describes in details: Functional requirements

Business processes

Actors and use-cases

Non-functional requirements

E.g. performance, scalability, etc.


12/49


It is always hard to describe anddocument the requirements incomprehensive and not ambiguous way

Good requirements save time and money

Requirements always change during theproject!

Good software requirementsspecification reduces the changes

Prototypes significantly reduce changes


13/49


Specification and UIPrototype Examples


14/49

Software Architectureand Software Design

S ft A hit t d


15/49

Software Architecture andSoftware Design

Software designis a technicaldescription about how the system willimplement the requirements

The sys tem archi tecturedescribes: How the system will be decomposed

into subsystems (modules)

Responsibilities of each module

Interaction between modules

Platforms and technologies

S t A hit t


16/49

System ArchitectureDiagram Example


17/49

Software Design

Detailed Design

Describes the internal module structure

Interfaces, data design, process design

Object-Oriented Design Describes the classes, their

responsibilities, relationships,dependencies, and interactions

Internal Class Design

Methods, responsibilities, algorithms and

interactions between them

S ft D i D t


18/49

Software Design Document(SDD)

The Software Design Document (SDD)isa formal description of the architectureand design of the system

It contains:

Architecture design

Modules and their interaction (diagram)

For each module

Process design (diagrams)

Data design (E/R diagram)

Interfaces design (class diagram)


19/49

Software Design

Document Example


20/49

Software Construction

Implementation, Unit Testing,

Debugging, Integration


21/49

Software Construction

During the so f tware construct ionphasedevelopers create the software

Sometimes called implementat ionphase

It includes: Internal method design

Writing code

Writing unit tests (sometimes)

Testing and debugging

Integration


22/49

Writing the Code

Codingis the process of writing theprogramming code (the source code)

The code strictly follows the design

Developers perform in ternal methoddesignas part of coding

The sou rce codeis the output of the

software construction process Written by developers

Can include unit tests


23/49

Testing the Code

Test ingchecks whether the developedsoftware conforms to the requirements

Aims to identify defects (bugs)

Developers test the code after write it At least run it to see the results

Unit test ingis even better

Units tests can be repeated many times

System testing is done by QA engineers

Unit testing is done by developers


24/49

Debugging

Debuggingaims to find the source ofalready identified defect and to fix it

Performed by developers

Steps in debugging: Find the defect in the code

Identify the source of the problem

Identify the exact place in code causing it

Fix the defect

Test to check if the fix is correct


25/49

Integration

Integrationis putting all pieces together Compile, run and deploy the modules as

single system

Test to identify defects

Integration strategies

Big bang, top-down and bottom-up

Continuous integration

Coding != Software


26/49

Coding != SoftwareEngineering

Inexperienced developers considercoding the core of development

In most projects coding is only 20% ofthe project activities!

The important decisions are taken duringthe requirements analysis and design

Documentation, testing, integration,maintenance, etc. are often disparaged

Software engineering is not just coding!

Programmer!= so ftware engineer


27/49

Software Verification

and Testing


28/49

Software Verification

What is so ftware veri f icat ion? It checks whether the developed software

conforms to the requirements

Performed by the Software QualityAssurance Engineers (QA)

Two approaches:

Formal reviewsand inspect ions

Different kinds oftest ing

Cannot certify absence of defects!

Can only decrease their rates


29/49

Software Testing

Test ingchecks whether the developedsoftware conforms to the requirements

Testing aims to find defects (bugs)

Black-box and white-box tests

Unit tests, integration tests, system tests,acceptance tests

Stress tests, load tests, regression tests

Tester engineers can use automated testtools to record and execute tests


30/49

Software Testing Process

Test planning Establish test strategy and test plan

During requirements and design phases

Test development

Test procedures, test scenarios, testcases, test scripts

Test execution

Test reporting

Retesting the defects


31/49

Test Plan and Test Cases

The test p lanis a formal document thatdescribes how tests will be performed

List of test activities to be performed to

ensure meeting the requirements Features to be tested, testing approach,

schedule, acceptance criteria

Test scenarios and test cases Test scenarios stories to be tested

Test cases tests of single function


32/49

Test Plans and Test

Cases Example


33/49

Software Project

Management

What is Project


34/49

What is ProjectManagement?

Project managementis the discipline oforganizing and managing resources inorder to successfully complete a project

Successfully means within definedscope, quality, time and cost constraints

Project constraints:Scope

Quality

Project Success

What is Software Project


35/49

What is Software ProjectManagement?

Software pro ject management Management discipline about planning,

monitoring and controlling softwareprojects

Project p lann ing

Identify the scope, estimate the workinvolved, and create a project schedule

Project mon i tor ing and con t ro l

Keep the team up to date on the project'sprogress and handle problems


36/49

What is Project Plan?

The pro ject p lanis a document thatdescribes how the work on the projectwill be organized

Contains tasks, resources, schedule,milestones, etc.

Tasks have start, end, assignedresources (team members), % complete,dependencies, nested tasks, etc.

Project management tools simplifycreating and monitoring project plans


37/49

Project Plan Example


38/49

Development

Methodologies

What is a Development


39/49

What is a DevelopmentMethodology?

A development methodo logyis a set ofpractices and procedures for creating

software

A set of rules that developers have tofollow

A set of conventions the organization

decides to follow

A systematical, engineering approach for

organizing software projects


40/49

Development Methodologies

The "Waterfall" Process Old-fashioned, not used today

Rational Unified Process (RUP)

Very formal, lots of documentation

Microsoft Solutions Framework (MSF)

Formal heavyweight approach Agile Development Processes

E.g. Extreme Programming


41/49

The Waterfall DevelopmentProcess

Th W t f ll P


42/49

The Waterfall Process

The waterfall development process:

Software

Requirements

SoftwareDesign

Implementation

(Coding)

Verification

(Testing)

Operation

(Maintenance)

F l M th d l i


43/49

Requirements

System

Requirements

Formal Methodologies

Formal methodologies are heavyweight!

Software

Requirements

Analysis

Coding

Testing

Operations

Design

Analysis

Detailed

Design

PreliminaryDesign

Document

UI Design

Document Test

Plan

Preliminary

DesignSoftware

Requirements

SpecificationPrelim.

Revie

w

Program

Design

Design Review

OperatingInstructions

Coding

Integration

Testing

Usage

Code

Review

Lots of documents,diagrams, etc.

Final

Design


44/49

Agile Development

Th A il M if t


45/49

The Agile Manifesto

Our highest priority is to satisfy the

customer through early and continuous

delivery of valuable software

Manifesto for Agi le

Th A il S i it


46/49

Incremental Working sof twareover comprehensive

documentation

Cooperation

Customer col laborat ionover contractnegotiation

Straightforward

Ind iv iduals and interact ion sover processesand tools

Adaptive

Responding to changeover following a plan

The Agile Spirit

A il M th d l i


47/49

Agile Methodologies

eXtreme Programming (XP) Scrum

Crystal family of methodologies

Feature-Driven Development (FDD)

Adaptive Software Development (ASD)

Dynamic System Development Model(DSDM)

Agile Unified Process (AUP)

Extreme Programming:


48/49

Extreme Programming:The 12 Key Practices

The Planning Game

Small Releases

Metaphor

Simple Design

Test-Driven Development Refactoring

Pair Programming

Collective Ownership

Continuous Integration

40-Hour Workweek

On-site Customer

Coding Standards



49/49

Software EngineeringFundamentals

Questions?

Software Engineering Fundamentals Svetlin Nakov774

Documents

Transcript of Software Engineering Fundamentals Svetlin Nakov774