CIS 115

Lecture 26: Software Engineering

Early Programmers

Image Source: Wikipedia

1945 - 65: Early Software

• Many software pioneers were women!
• Early computers were very specialized; software was rewritten
• Led to high-order languages like FORTRAN, COBOL, ALGOL
• Conferences held in 1968 and 1969 started the field

1965 - 85: Software Crisis

• Many projects ran over budget and schedule
• Bad software could cause damage or even death!
• The field needed to be standardized

1985 - 89: No Silver Bullet

• Unfortunately, no single solution to make software better
• 1995 study: 1/2 of software projects operational but not successful
• Average software project overshoots schedule by half
• 3/4 of large software projects either not used or don't meet all requirements

1990 - 2000: Rise of the Internet

• Software made more use of the network
• Graphics became more important
• Software was becoming more and more consumer focused
• Viruses, search engines, email, etc.

2000 - Present: Lightweight Methodologies

• Agile development: focus on velocity
• Use of models and reused code to ease development
• Software "families" avoid the need to recreate software from scratch

Software Development Life Cycle

• Requirements
• Specification
• Architecture
• Construction & Design
• Testing & Debugging
• Deployment & Maintenance

Requirements Elicitation

• Contact stakeholders
• Gather information
• List requirements
• Determine target & goals
• Use Cases
• Verify correctness

Requirements

Image Source: Wikipedia

Use Cases

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Software Specification

• Describes how the system should function
• Lists inputs and outputs
• Should clearly match the requirements

Software Specification

Image Source: Wikipedia

Software Architecture

• High-level overview of how the software should be built
• Accounts for multiple stakeholders, separation of concerns, recurring styles or models, etc.
• Gives developers a framework to work with

Software Design & Construction

• Developers refine the architecture diagram by adding features and solidifying individual design components
• Usually several layers of diagrams are made for larger software projects

UML Diagram

Image Source: Oracle

Software Testing & Debugging

• Verifying the software works correctly
• Errors can be introduced at any step of the process
• Unfixed errors can cause massive problems down the road
• The longer an error is unfixed, the more it takes to fix it

Deployment & Maintenance

• Once software is created, it must be given to clients
• Larger software packages require more deployment effort
• Once software is deployed, bugs may still be found and must be patched
• Updates may be issued to add more features

Development Models

• Code & Fix
• Waterfall
• Iterative / Incremental
• Spiral
• Agile

Waterfall

Image Source: Wikipedia

Iterative

Image Source: Wikipedia

Spiral

Image Source: Wikipedia

Agile (Scrum)

Image Source: Wikipedia

Globalization

• Software is GLOBAL!
• Companies can "follow the sun"
• Development can happen 24 hours a day
• Communication and collaboration is key to success

Assignments

• Blog 12: Cybersecurity - Due 4/27 10PM
• Scratch Game Project - Due 5/5 10PM
  
• Wiki Draft - Due 4/24 10PM
• Wiki Final Version - Due 5/8 10PM

Blog 12: Cybersecurity Incidents

Cybersecurity is a major aspect of computer science today, and there have been many instances of high-profile organizations being hacked or large pieces of software being found to be vulnerable to an attack. Choose a particular incident in cybersecurity and tell us more about it. Things you can include:

• Who, what, when, where, why and how?
• Is this attack or vulnerability still an issue today? Or has this been patched/fixed?
• What was the damage?
• Did this affect a large number of people or a smaller targeted group?
• Was anyone ever caught? Did they suffer any consequences?
• Did this event cause groups to rethink their cybersecurity plans?

Work on Wiki Project Drafts