Robert L. Glass - Facts and Fallacies of Software Engineering

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Library of Congress Cataloging-in-Publication Data

Glass, Robert L., 1932
Facts and fallacies of software engineering / Robert L. Glass.
p. cm.
Includes bibliographical references and index.
ISBN 0-321-11742-5 (alk. paper)
1. Software engineering I. Title.

QA76.758 .G52 2003
005.1'068'5--dc21 2002027737

Copyright 2003 by Pearson Education, Inc.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form, or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior consent of the publisher. Printed in the United States of America. Published simultaneously in Canada.

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ISBN 0-321-11742-5

Text printed in the United States on recycled paper at RR Donnelley Crawfordsville in Crawfordsville, Indiana.

9th Printing July 2008

This book is dedicated to the researchers who lit the fire of software engineering and to the practitioners who keep it burning.

To Paul Becker,
now of Addison-Wesley, who has been the editor for nearly all of my non-self-published books, for his belief in me over the years.

To Karl Wiegers,
for his contributions of frequently forgotten fundamental facts and for the massive job of reviewing and massaging what I wrote.

To James Bach, Vic Basili, Dave Card, Al Davis, Tom DeMarco, Yaacov Fenster, Shari Lawrence Pfleeger, Dennis Taylor, and Scott Woodfield, for the hugely important task of helping me identify appropriate citations for the sources of these facts.

When I first heard that Bob Glass was going to write this book and model it after my 201 Principles of Software Development, I was a bit worried. After all, Bob is one of the best writers in the industry, and he would provide tough competition for my book. And then, when Bob asked me to write his foreword, I became even more worried; after all, how can I endorse a book that seems to compete directly with one of mine? Now that I have read Facts and Fallacies of Software Engineering, I am pleased and honored (and no longer worried!) to have the opportunity to write this foreword.

The software industry is in the same state of affairs that the pharmaceutical industry was in during the late nineteenth century. Sometimes it seems that we have more snake-oil salespeople and doomsayers than sensible folks practicing and preaching in our midst. Every day, we hear from somebody that they have discovered this great new cure for some insurmountable problem. Thus we have oft heard of quick cures for low efficiency, low quality, unhappy customers, poor communication, changing requirements, ineffective testing, poor management, and on and on. There are so many such pundits of the perfunctory that we sometimes wonder if perhaps some portion of the proclaimed panaceas are possibly practical. Whom do we ask? Whom in this industry can we trust? Where can we get the truth? The answer is Bob Glass.

Bob has had a history of providing us with short treatises on the many software disasters that have occurred over the years. I have been waiting for him to distill the common elements from these disasters so that we can benefit more easily from his many experiences. The 55 facts that Bob Glass discusses in this wonderful book are not just conjectures on his part. They are exactly what I have been waiting for: the wisdom gained by the author by examining in detail the hundreds of cases he has written about in the past.

The 55 facts that follow are likely not to be popular with all readers. Some are in direct opposition to the so-called modern ways of doing things. For those of you who wish to ignore the advice contained within these covers, I can wish you only the safest of journeys, but I fear for your safety. You are treading on well-trod territory, known to be full of mines, and many have destroyed their careers trying to pass. The best advice I can give you is to read any of Bob Glasss earlier books concerning software disasters. For those of you who wish to follow the advice contained herein, you too are following a well-trod path. However, this path is full of successful testimonies. It is a path of awareness and knowledge. Trust Bob Glass because he has been there before. He has had the privilege of analyzing his own successes and failures along with hundreds of others successes and failures. Stand on his shoulders, and you will more likely succeed in this industry. Ignore his advice, and be prepared for Bob to call you in a few years to ask you about your projectto add it to his next compilation of software disaster stories.

Alan M. Davis
Spring 2002

Authors Addendum:

I tried to get Al Davis to tone down this foreword. It is, after all, a bit syrupy sweet. But he resisted all of my efforts. (I really did try! Honest!) In fact, in one such exchange, he said, You deserve to be on a pedestal, and Im happy to help you up! My experience with being on pedestals is that, inevitably, you fall off, and when you do, you break into Humpty-Dumpty-like insignificant fragments.

But regardless of all that, I cannot imagine greater and more wonderful sentiments than the ones Al bestows on me here. Thanks!

Robert L. Glass
Summer 2002

This book is a collection of facts and fallacies about the subject of software engineering.

Sounds boring, doesnt it? A laundry list of facts and fallacies about building software doesnt sound like the kind of thing youd like to kick back and spend an hour or two with. But theres something special about these facts and fallacies. Theyre fundamental. And the truth that underlies them is frequently forgotten. In fact, thats the underlying theme of this book. A lot of what we ought to know about building software we dont, for one reason or another. And some of what we think we know is just plain wrong.

Who is the we in that previous paragraph? People who build software, of course. We seem to need to learn the same lessons over and over again, lessons that these factsif rememberedmight help us avoid. But by