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1 UNDERGRADUATE TEXTS IN COMPUTER SCIENCE Editors David Gries Fred B. Schneider Springer NewYork Berlin Heidelberg Barcelona Budapest HongKong London Milan Paris Santa Clara Singapore Tokyo

2 UNDERGRADUATE TEXTS IN COMPUTER SCIENCE Beidler, Data Structures and Algorithms Ja/ote, An Integrated Approach to Software Engineering, Second Edition Kozen, Automata and Computability Merritt and Stix, Migrating from Pascal to C++ Zeig/er, Objects and Systems

3 Pankaj Jalote AN INTEGRATED APPROACH TO SOFTWARE ENGINEERING Second Edition With 108 Illustrations " Springer

4 Pankaj Jalote Department of Computer Science and Engineering Indian Institute of Technology Kanpur India Series Editors David Gries Fred B. Schneider Department of Computer Science Comell University UpsonHall Ithaca, NY USA Library of Congress Cataloging-in-Publication Data Jalote, P. An integrated approach to software engineering / Pankaj Jalote. - 2nded. p. cm. - (Undergraduate texts in computer science) IncIudes bibliographical references and index. 1. Software engineering I. Title. H. Series. QA J dc Printed on acid-free paper. ISBN DOI / ISBN (ebook) 1997, 1991 Springer-Verlag New York, Inc. Softcover reprint of the hardcover 2nd edition 1997 All rights reserved. This work may not be translated or copied in whole or in part without the written permission ofthe publisher (Springer-Verlag New York, Inc., 175 Fifth Avenue, New York, NY 10010, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use of general descriptive names, trade names, trademarks, etc., in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone. Production managed by Steven Pisano; manufacturing supervised by Johanna Tschebull. Camera-ready copy prepared from the author's Jb.TPC files

5 Preface to the Second Edition A lot has changed in the fast-moving area of software engineering since the first edition of this book came out. However, two particularly dominant trends are clearly discernible: focus on software processes and object-orientation. A lot more attention is now given to software processes because process improvement is considered one of the basic mechanisms for improving quality and productivity. And the object-oriented approach is considered by many one of the best hopes for solving some of the problems faced by software developers. In this second edition, these two trends are clearly highlighted. Aseparate chapter has been included entited "Software Processes." In addition to talking about the various development process models, the chapter discusses other processes in software development and other issues related to processes. Object-orientation figures in many chapters. Object-oriented analysis is discussed in the chapter on requirements, while there is a complete chapter entitled "Object-Oriented Design." Some aspects of object-oriented programming are discussed in the chapter on coding, while specific techniques for testing object-oriented programs are discussed in the chapter on testing. Overall, if one wants to develop software using the paradigm of object -orientation, ab aspects of development that require different handling are discussed. Most of the other chapters have also been enhanced in various ways. In particular, the chapters on requirements specification and testing have been considerably enhanced. The focus of the book remains an introductory course on software engineering; advanced topics are still not included. The basic case study-based approach of the book has been preserved. In addition to the structured design of the case study, the object-oriented design of the case study has been performed, and the design is described in the book. The structured design has now been implemented in C (in the

6 vi Preface to the Second Edition first edition the coding was done in Pascal), keeping in mind the growing popularity of the C language in cornmercial establishments. The object-oriented design has been coded in C++. Again, C++ was chosen mostly due to its high availability and popularity. Both the C and C++ code of the case study are available to readers from the horne page for the book. Metrics-based software development has been steadily gaining importance. This trend has been reftected in the book by placing greater emphasis on the role of metrics in software development. The use of some of the metrics in effecting the development process has been demonstrated on the case study. For example, metrics were used to evaluate, and then change, the design of the case study. Similarly, the C code was evaluated and then changed to reduce the complexity. Tools that were developed for metrics extraction and evaluation are also being made available through the horne page. A horne page has been created on the Web for this edition of the book, through which some of the documents and code of the case study and some of the tools used can be obtained. The URL of the horne page is The following material is available through the horne page (these are discussed at appropriate places in the book): 1. Design specifications for the structured design of the case study (both the initial and the final versions). 2. The C code implementing the final structured design of the case study (both the initial and the final versions). 3. The C++ code implementing the object-oriented design of the case study. 4. The following tools whieh have been used in the case study: dmetric-to evaluate the complexity of a design. complexi ty-to evaluate the complexity of ac program. style-to evaluate the style of ac program. ccov-a test coverage analyzer for C programs. I would like to express my gratitude to many people who readily clarified issues and provided feedback on various parts of the book. These include Frank McGarry; Professors Vietor Basili, Alan Davis, Ginaluigi Caldiera, Harish Karnik, and Mary Jean Harrold; and many others. I am partieularly grateful to Kamal K. Mantri, S. Haripriya, and G. Aditya Kiran for developing the C and C++ code for the case study, developing the tools used for evaluation, and performing experiments with the tools and various designs. I would also like to express my thanks to Infosys Technologies Ltd., Bangalore, where I am spending my sabbatical, for providing the necessary help to finish this edition. Comments about the book are welcome and can be sent by to jalote@iitk.ernet.in. Pankaj Jalote

7 Preface to the First Edition It is now c1ear that development of large software systems is an extremely complex activity which is full of various opportunities to introduce errors. Software engineering is the discipline that attempts to provide methods to handle this complexity and enable us to produce reliable software systems with maximum productivity. This book offers an integrated approach to software engineering. The "integrated" approach is different from others because the different topics are not covered in isolation. A running case study is employed, which is used throughout the book, illustrating the different activities of software development on the same project. Most ofthe major outputs ofthe project, such as the project plan, design document, code, test plan, test report, and so on, are shown for the case study. It is important, and very instructive, to not only teach the principles of software engineering but also apply them to a software development project so that all aspects of development can be seen c1early on a project. Such an approach, besides explaining the principles, also offers a case study which can be used as a model for a software development project by a student. Integration is further achieved by combining software metrics with the different development phases, instead of having aseparate chapter on the subject. It is recognized that metrics are used for controlling and assessing a software project and are employed throughout the life cyc1e. In the book, for each phase, relevant metrics and their use is discussed in the chapter for that phase. This conveys the right idea that metrics is not really a separate topic, complete in itself, but is integrated with the different activities of software development. Similarly, for each phase, quality assurance activities and the control activities that need to be performed while the activities of that phase are being done are described in the chapter for the particular phase.

8 viii Preface to the First Edition The sequence of chapters is essentially the same as the sequence of activities performed during software development. All activities, including quality assurance and control activities, that should be performed during a particular phase are grouped in one chapter. This is particularly useful for a project-based introductory course in software engineering in which both the students and the instructor can follow the chapters in the order given both in the lectures as weil as in the project. This book is for students who have not had previous training in software engineering, and it is suitable for a one-semester course. In order to limit the scope of the book and focus it for an introductory course, advanced topics like software reuse, reverse engineering, development environments, and so on, have not been included. It was feit that in an introductory course, rather than trying to give a ftavor of all the topics, it would be best to introduce the student to the discipline of software engineering as weil as to some of the important topics, and to prepare the student for taking advanced courses in the area of software engineering. This need was further feit since in the undergraduate computer science curriculum of most universities, the students have no exposure to software engineering prior to the introductory course, and often do not have any other foilow-up course before they graduate. One of the goals of the book, then, is to include only as much material as can be covered in a one-semester course, which may be the only software engineering course in a computer science student's education. I am grateful to my coileagues Vietor R. Basili and Dieter Rombach for their valuable inputs during the conceptual stages. I am particularly grateful to students in the software engineering courses that I taught at the University of Maryland and the Indian Institute of Technology, Kanpur. Teaching and interacting with the students had a great inftuence on the final form of the book. Students in my course at the Indian Institute of Technology, partieularly Sandeep Sharma and Samudrala Sridhar, deserve special thanks for helping with the case study.

9 Contents Preface to the Second Edition Preface to the First Edition 1 Introduction 1.1 The Software Problem Software Is Expensive Late, Costly, and Unreliable Problem of Change and Rework 1.2 Software Engineering Problem The Problem of Scale Cost, Schedule, and Quality The Problem of Consistency 1.3 The Software Engineering Approach Phased Development Process Project Management and Metrics 1.4 Summary Overview of the Book. Exercises... 2 Software Processes 2.1 Software Process Processes, Projects, and Products Component Software Processes. 2.2 Characteristics of a Software Process Predictability... v vii

10 x Contents Support Testability and Maintainability Early Defect Removal and Defect Prevention Process Improvement Software Development Process A Process Step Specification Waterfall Model Prototyping Iterative Enhancement The Spiral Model Project Management Process Phases of Management Process Metrics, Measurement, and Models. 2.5 Software Configuration Management Process Configuration Identification Change Control Status Accounting and Auditing 2.6 Process Management Process Building Estimation Models Process Improvement and Maturity 2.7 Summary Exercises Software Requirements Analysis and Specification 3.1 Software Requirements Need for SRS Requirement Process 3.2 Problem Analysis Analysis Issues Informal Approach Structured Analysis Object-Oriented Modeling Other Modeling Approaches Prototyping Requirements Specification Characteristics of an SRS Components of an SRS Specification Languages Structure of a Requirements Document 3.4 Validation Requirement Reviews Other Methods 3.5 Metrics Size Measures Quality Metrics

11 Contents xi 3.6 Summary 146 Exercises 147 Case Study Planning a Software Project Cost Estimation... a Uncertainties in Cast Estimatian Building Cost Estimation Models On Size Estimation COCOMO Model An Example Project Scheduling Average Duration Estimation Project Scheduling and Milestones Example Continued Staffing and Personnel Planning Rayleigh Curve Personnel Plan Example Cantinued Team Structure Software Configuration Management Plans Quality Assurance Plans Verification and Validation (V& V) Inspections and Reviews Project Monitoring Plans Time Sheets Reviews Cast -Schedule-Milestone Graph Earned Value Method Unit Development Folder Risk Management Risk Management Overview Risk Assessment Risk Control Summary 201 Exercises Case Study Plan Function-Oriented Design Design Principles Problem Partitioning and Hierarchy Abstraction Modularity Top-Down and Bottom-Up Strategies. 215

12 xii Contents 5.2 Module-Level Concepts Coupling Cohesion Design Notation and Specification Structure Charts Specification Structured Design Methodology Restate the Problem as a Data Flow Diagram Identify the Most Abstract Input and Output Data Elements First-Level Factoring Factoring the Input, Output, and Transform Branches Design Heuristics Transaction Analysis Discussion Verification Design Reviews Automated Cross-Checking Metrics Network Metrics Stability Metrics Information Flow Metrics Summary 249 Exercises 251 Case Study Object-Oriented Design Analysis and 00 Design Concepts Classes and Objects Relationships Among Objects Inheritance and Polymorphism Design Concepts Design Notation and Specification Design Methodology Dynamic Modeling Functional Modeling Defining Internal Classes and Operations Optimize and Package Examples Metrics Summary 315 Exercises 316 Case S~udy.. 318

13 Contents xiii 7 Detailed Design Module Specifications Specifying Functional Modules Specifying Classes Detailed Design PDL Logic/ Algorithm Design State Modeling of Classes Verification Design Walkthroughs Critical Design Review Consistency Checkers Metrics Cyclomatic Complexity Data Bindings Cohesion Metric Summary 352 Exercises Coding Programming Practice Top-Down and Bottom-Up Structured Programming Information Hiding Programming Style Internal Documentation Law of Demeter for 00 Programs Verification Code Reading Static Analysis Symbolic Execution Proving Correctness Code Inspections or Reviews Unit Testing Metrics Size Measures Complexity Metrics Style Metrics Summary 393 Exercises 395 Case Study Testing 9.1 Testing Fundamentals

14 xiv Contents References Index EITor, Fault, and Failure Test Orades Top-Down and Bottom-Up Approaches Test Cases and Test Criteria Psychology oftesting Functional Testing Equivalence Class Partitioning Boundary Value Analysis Cause-Effect Graphing Special Cases Structural Testing Control Flow-Based Criteria Data Flow-Based Testing An Example Mutation Testing Test Case Generation and Tool Support. 9.4 Testing Object-Oriented Programs Issues in Testing Classes State-Based Testing Incremental Testing for Subdasses 9.5 Testing Process Comparison of Different Techniques Levels of Testing Test Plan Test Case Specifications Test Case Execution and Analysis. 9.6 Metrics-Reiiability Estimation Basic Concepts and Definitions Musa's Basic Model Failure Data and Parameter Estimation Translating to Calendar Time An Example. 9.7 Summary Exercises Case Study