CMSC 345 Fall 2000

Software Design and Development

Instructor

Instructor: Dennis L. Frey

Office: ECS 222

Email: frey@cs.umbc.edu

Office Hours: TuTh 10:00 – 12:00

TA

TA: Mahesh Gandhe

Office:

Email: mgandh1@gl.umbc.edu

Office Hours: MW TBD

Course Materials Course homepage

www.cs.umbc.edu/courses/undergraduate/345/fall00

Course Description Objective Textbooks Grading

Class Schedule

What is Software Engineering? SW Engineering focuses on the

computer as a problem-solving tool instead of investigating HW design or proving theorems about algorithms

Any hacker can write code. SW Engineering is about designing and developing high-quality software

Why Software Engineering Writing a program is easy Developing a software product is hard High-quality software products are robust,

efficient and effective High-quality software products are easy to

understand, modify and compose with other high-quality software products

Software engineers are skilled professionals who follow “best practices”

Management MythMyth: If we get behind schedule, we can

add more programmers to catch up.

Reality: The mythical man-month - “… adding people to a late software project makes it later”. Why?

People can be added, but in a planned and well-coordinated manner.

Customer Myth

Myth: A general statement of objectives is sufficient, we will fill in the details later.

Reality: Poor up-front definition is the major cause of failed software efforts.

Customer Myth Myth: Project requirements continually

change, but change can easily be accommodated because software is flexible.

Reality: It is true that software requirements do change, but the impact of change varies with the time the change is introduced.

Cost of Change

Development

Definition Maintenance

1

1.5

to

6

60

to

100

Practitioner Myth

Myth: Once we write the program and get it to work, our job is done.

Reality: Industry data shows that 50%-70% of all effort expended on a program is expended after it is delivered to the customer.

Practitioner Myth

Myth: The only deliverable for a successful project is the working program.

Reality: A working program is only one part of the software configuration. Documentation forms the foundation for a successful development and provides guidance for the software maintenance task.

Who does SW Engineering? Stakeholders working together as

a team. Usually 3 categories

Customer User Developer

CUSTOMER Sponsors systemdevelopment

USER

Usessystem

DEVELOPER

Buildssystem

Contractualobligation

$$$,needs

Software system

Needs

A Systems Approach Projects do not exist in a vacuum Must provide a context

System Boundaries Elements of a system

Activities Objects (Entities) Relationships Definition of the boundary

Building the system Determine the requirements Create a system design Design individual programs Test the programs in pieces Test the programs together Deliver the system

The Development Team Requirements analyst Designers Programmers Testers Customers Trainers Maintenance team

MAINTENANCE

SYSTEMDESIGN

REQUIREMENTSANALYSIS AND DEFINITION

PROGRAMDESIGN

PROGRAMIMPLEMENTATION

UNITTESTING

INTEGRATIONTESTING

SYSTEMTESTING

SYSTEMDELIVERY

SO

FTW

AR

E D

EV

ELO

PM

EN

T S

TE

PS

DE

VE

LOPE

R R

OLE

SANALYST

DESIGNER

PROGRAMMER

TESTER

TRAINER

The Product Elementary School mathematics

testing system User interface Database Multiple user types Reporting

New Skills GUI on Unix

Tcl/Tk curses

RCS for version control Multi-user system design

client/server