SE 1 - Introduction

Software Engineering Notes

History of software engineering

• First digital computer apeared in eraly 1940s.
• It came up with stored program architecture ( store program instructions in electrical memory or von neumann architecture)
• Program languages started to apear in 1950s. ( Fortran , ALGOL , COBOL )
• Software crysis - facing to chalangers to develop softwares , increasing complexity and demand
• NATO in 1968 is organized to discuss software crysis

Software engineering Key-words

• deliver the required fuctionality 
• performance
• maintainable
• dependable
• usable

Importance of Software

• Economical compared to hardware
• Automation & efficiency 
• Commiunication & Creativity
• Data managment
• More systems are software controlled

Importance of Software Engineering

• Society relies on advanced software systems to  produce reliablity , maintainability and usability , economically and quickly.It can run in long in low cost.

Difference between software engineering and computer science

Computer science is focued on theories , fundamentals and new concepts while software engineering is developing new systems through the concepts and maintain them.

The Best SE Techniques and Methods

There is not a specific technique or method in SE , it depends on the software type  ( Security Software , Real-Time Software , Critical Systems ) , user requirements , background of developing team

Security Software - Antivirus , Firewallls , Password managers

Real-Time Software - Flight Control System  , Medical Devices , Online Gaming

Critical Systems - Air traffic contorl system , Nuclear power plant system , Spacecraft and navigation system

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1. Agile Development
2. Waterfall Model
3. DevOps
4. Spiral Model
5. Extreme Programming (XP)
6. Rapid Application Development
7. V-Model (Validation and verification )

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Software Products

Generic Products - stand-alone application that are marketed and sold to any customer who wants it.

Customized Products - Systems that made for specific target people or organization to meet thier requirements.

Open-Source Products - Free and commiunity driven softwares

Embedded Systems - Software Integrated into hardware devices

Attributes of a Good Software

• Deliver required fuctionality 
• Deliver a good performance
• Usability and Maintainable 
• Testablity and Reliablity

Essential Attributes for quality software

• Efficiancy 
• Acceptability
• Maintainability
• Dependability
• Security

Fundamental In SE

• Software specification
  • Mainly customer requirements , both developers and customer involve
• Software design and development
  • Design the system and program it
  • Database Structure
  • Class diagram
  • Timing diagram
  • Colloboration diagram
  • Case diagrams
  • SRS - Software Requirement Specification
• Software validation
  • Testing to ensure user requirements are met
• Software evolution / maintance
  • Change the build software to meet changing user requirements and marketing perpose.

Software Cost

Cost that spend when developing a system or maintaining it -- ( > greater than mark ) 

• Software cost > Computer system cost
• Development cost > Testing cost -
  • Development cost - 60%
  • Testing cost - 40%
• Maintaince cost > Development cost

Application Types

Software is a broad term referring to any set of instructions that tells a computer what to do, while an application is a specific type of software designed for a particular task or set of tasks.

• Stand-alone applications
  • Runs on local computer , no need network
    • Office package
    • CAD softwares
• Interactive transaction based application
  • Execute on a remote computer but access using PCs or Terminals
    • e-commerce application
    • Food delivery apps
    • Ticket booking platforms
• Embedded control system
  • Software contorl systems , Control and manage hardware., majority of softwares.
    • Engine Control Units - ECU
    • Antilock Braking System - ABS
    • Printers
• Batch Processing Systems
  • Process data in large batches
    • Payroll proccesing
    • Utility bill generation
    • Acedemic grading system
• Entertrainment Systems
  • Primaraliy for personal usage
    • Video game consoles
    • Meadia streaming platforms / devices
    • Virtual reality
• System for modeling and simulation
  • Developed by scienstists and engineers to model physical activity and situations.
    • Computational fluid dynamics
    • Electronic circuit simulators
    • Agent based modeling
• Data collection Systems
  • Collect data from environmet using sensors , then send them to process.
    • Traffic Controlling system
    • Field data collecting applications
    • Web analytical apps
• Systems of system
  • Composed (යොදනවා) on other computer systems.
    • Ballistic Missile Defense System
    • Integrated Healthcare Delivery System
• AI based system
  • Computer system or application that incorporates AI to perfom a task.
    • Virtual personal assistanst
    • Self driving vehicals
    • Image and facial recognize system

Software Project Failures

• People
  • Social interaction
  • Skills
  • Motivation
• Tasks
  • Sale customers
  • Requirements
  • Project managment
  • Quality Control
  • Software Testing
• Methods
  • Devepolment Work
  • User project team
  • Top Management
  • External agents
• Environment
  • Project compinity
  • Available assets
  • Policies technologies
  • Bussiness domain
  • Organization Structure

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• Examples
• Incomplete reqiurements
• Lack of user involvement
• Lack of resource
• Unrealistic Expectations
• Lack of executive support
• Changing requrements & specifications

Web Software Engineering

Increased availability of software and developing highly distributed services based systems.Provide commiunication functionality over the internet ( web service ) , Provide platform for running apps , us e cloud computing.

• Google docs
• Notion
• Amazon
• Github
• Moodle

Key Challangers 

• Meeting Deadlines
• Colloboration & Commiunication
• Technical Debt
• Security concerns
• Keeping up with new technologies
• Complexity managment
• Trustworthy
• Reduce delivery times

Software engineering Ethics

• Respect the confidentiality of employees and clients
• Shouldn't mispresent the level of competence
• Should be aware of local lawas governing the use of intellecctual property
• Protect intellectual (බුද්ධිමය) peroperties of employees and clients.
• Shouldn't use technical knowledge to misuse other computers
• Must behave in ethical and responsible way
• Follows a set of morally correct principles