Software Engineering Overview 23 January

Software Engineering Overview What is engineering? Why is software engineering different than other engineering disciplines? Is software engineering different than computer science? programming? How similar or different are software engineering projects?

Engineering Turning ideas into reality Creating something useful from other things using science and math

Software Engineering vs. Other Engineering Disciplines Maturity Roman aqueducts 2000 years ago Software engineering 50 years ago Startup costs Barriers to entry Rate of change

What’s in a Name? Software engineer Computer scientist Programmer Coder Developer Designer Architect

Different Types of Projects Consider 4 different types of systems COMP 523 projects Productivity suites Commercial web sites Airplane systems Pacemakers How do they differ in criticality? What does that mean for the development process?

Expectations of Software Engineering (Watts Humphrey)Watts Humphrey 1. Predetermine quantitative quality goals 2. Accumulate data for use in later projects 3. Keep all work visible 4. Design, program and test only against requirements 5. Measure and achieve quality goals

Keeping Work Visible: Documentation What will be implemented Customer: contract, requirements, “glossy” User: manuals How it will be implemented Project plan The code The test plan What people will do How you will manage code and documents

Documentation Principles Need to reflect changes Version control Need to keep all documents synchronized Single owner Only say it once

Quality Management Principles Customer focus Leadership Involvement of people Process approach System approach to management Continual improvement Factual approach to decision making Mutually beneficial supplier relationships

Customer Focus Organizations depend on customers Understand needs, requirements, expectations Increases market share Implies Market research Customer understanding throughout the organization Measuring satisfaction

Involvement of People Essence of the organization “Buy in” Two way street Treating people with respect They will take on ownership of responsibility Encourage a collaborative environment

Software Engineering Fundamental Steps Requirements Design Implementation Integration Test (elaborated versions to be covered later)

Processes Differ by how often you do the steps Points on the spectrum Differences in overhead Three fundamental models Waterfall Spiral Iterative

Waterfall Do it once Traditional model Used for large next version releases, especially when tightly coupled changes Pros Simple documentation management Clean design phase Cons Least flexibility No early feedback

Spiral Few iterations Each iteration adds new requirements Used often for projects with less well defined requirements Pros Adaptation to changes based on risks Good customer interaction Early version Limited iterations provide phase structure Cons Document maintenance

Iterative Many iterations Each iteration is on a fixed cycle Typically weekly Used for projects with lots of small independent, but well understood, changes Pros Fast feedback on problems Very adaptable to any changes Lots of versions to work with Cons Document maintenance Code maintenance Requires good automation