Software Engineering: An Introduction

Prof. David Bernstein
James Madison University

Computer Science Department

bernstdh@jmu.edu

What is Software?

To the Hardware:
- A collection of instructions to be executed by a computer/processor
To the Developer:
- A collection of human-readable statements (in a language) that can be converted to a collection of instructions to be executed by a computer/processor

The Organization of Software

Program:
- Any piece of software that can "run on its own" (including utilities, tools, scripts, apps, etc...)
Sub-Program:
- A collection of instructions/statements that implement an algorithm for accomplishing a specific task or tasks
Library:
- A group of related sub-programs for accomplishing a specific collection of (usually related) tasks

From Software to Software Product

What People (Other than Us) Care About:
- Having everything they need to solve one or more problems or achieve one or more goals (i.e., a complete means to one or more ends)
Definition:
- A software product is one or more programs, sub-programs, or libraries, along with the data and supporting materials and services, that a client can use to solve problems or achieve goals

Kinds of Software Products

Bespoke:
- Software products that are developed (usually under contract) for a specific client
Generic:
- Software products that are developed (usually speculatively) and then sold to market clients (either a mass market or a niche market)

Software Engineering

Defined:
- The application of (scientific) theories, methods and tools to the specification, design, creation, verification/validation, deployment, operation, and maintenance of software products
Scope:
- From specification to maintenance
- Involves technical and managerial concerns
- Involves theories/methods from psychology, mathematics/statistics, computer science, and management (of people and resources)
- Consists of science and art

Software Engineering vs. Computer Science/Engineering

Computer Engineering:
- The application of theories (often from physics) to the creation of computational devices
- Usually thought of as a subset of electrical and electronic engineering
Computer Science:
- The theories and methods that underlie computation and the use of computational devices