Just Enough Systems Engineering A review of the basics and how to use them 2010 © Dwayne Phillips About the Author Dwayne Phillips worked as a systems and computer engineer for 28 years for the U.S. Government. He is now a systems engineer with ITT in Herndon, Virginia. He lives with his wife of over 25 years Karen and near his three sons and (as of now) one daughter-in-law and one grandson. Dwayne’s web site is http://dwaynephillips.net and his email address is [email protected]. If you have any questions from this book, please ask Dwayne. If you find any typos or other errors in this book, don’t hesitate to contact Dwayne. About the Artist The cartoons in this book were drawn by Mr. Mark Tatro of Rotate Graphics (rotategraphics.com). Working with Mark is a pleasure. Contact him at [email protected] if you would like him to do art for you. About your rights and my rights Dwayne Phillips wrote this book and owns all commercial rights to it. 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If you know a publisher who would like to publish this material, please send them Dwayne’s information. 2010 © Dwayne Phillips Table of Contents SECTION 1 ..........................................................................................................................................................................6 SYSTEMS ENGINEERING....................................................................................................................................................6 1 SYSTEMS ENGINEERING IS... ..................................................................................................................................7 A DEFINITION....................................................................................................................................................................8 ANOTHER DEFINITION ......................................................................................................................................................9 A NON-DEFINITION...........................................................................................................................................................9 The Ten-Pound Pamphlet ........................................................................................................................................ 10 A LITTLE MORE DEFINITION......................................................................................................................................... 11 A Lazy Potato Farmer.............................................................................................................................................. 11 THE NOT-TO-DO LIST ..................................................................................................................................................... 13 COMMON SENSE AND COMMON PRACTICE................................................................................................................... 14 CLOSING THOUGHTS ...................................................................................................................................................... 14 SUGGESTED EXERCISES ................................................................................................................................................. 15 REFERENCES................................................................................................................................................................... 15 WHERE WE ARE NOW................................................................................................................................................ 16 SECTION 2 ....................................................................................................................................................................... 17 SYSTEMS ENGINEERING TECHNIQUES........................................................................................................................... 17 2 THE REQUIREMENTS .............................................................................................................................................. 18 GREAT BOOKS ON REQUIREMENTS ............................................................................................................................... 19 LEARNING THE REQUIREMENTS .................................................................................................................................... 20 IDENTIFYING THE REQUIREMENTS ................................................................................................................................ 22 MANAGING THE REQUIREMENTS................................................................................................................................... 24 CLOSING THOUGHTS ...................................................................................................................................................... 25 SUGGESTED EXERCISES ................................................................................................................................................. 26 REFERENCES:.................................................................................................................................................................. 26 WHERE WE ARE NOW................................................................................................................................................ 27 3 ARCHITECTURE ........................................................................................................................................................ 28 AN ARCHITECTURE ........................................................................................................................................................ 29 SOME PROPERTIES OF AN ARCHITECTURE .................................................................................................................... 31 USING AN ARCHITECTURE ............................................................................................................................................. 32 PUTTING NUMBERS INTO THE ARCHITECTURE ............................................................................................................. 36 ANOTHER EXAMPLE ARCHITECTURE............................................................................................................................ 37 CLOSING THOUGHTS ...................................................................................................................................................... 39 SUGGESTED EXERCISES ................................................................................................................................................. 40 REFERENCE: ................................................................................................................................................................... 40 WHERE WE ARE NOW................................................................................................................................................ 41 4 INTERFACES ............................................................................................................................................................... 42 EXAMPLE INTERFACES................................................................................................................................................... 43 LEVELS OF THE INTERFACE ........................................................................................................................................... 46 DEFINING AN INTERFACE............................................................................................................................................... 47 ANOTHER COUPLE OF INTERFACES ............................................................................................................................... 48 ARCHITECTURE AND INTERFACE: A SO-SO EPISODE................................................................................................... 52 CLOSING THOUGHTS ...................................................................................................................................................... 54 SUGGESTED EXERCISES ................................................................................................................................................. 55 WHERE WE ARE NOW................................................................................................................................................ 56 5 TRACING ...................................................................................................................................................................... 57 CLASSIC TRACING.......................................................................................................................................................... 57 TRACING AND CHANGES................................................................................................................................................ 62 A Change Scenario................................................................................................................................................... 62 Another Change Scenario.......................................................................................................................................