A COMPONENT BASED APPROACH TO AGENT SPECIFICATION

AFIT/GCS/ENG/00M-22

A COMPONENT BASED APPROACH TO AGENT SPECIFICATION THESIS

David J. Robinson, 1st Lieutenant, USAF AFIT/GCS/ENG/00M-22

DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY

AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base, Ohio

Approved for public release, distribution unlimited.

AFIT/GCS/ENG/00M-22

A COMPONENT BASED APPROACH TO AGENT SPECIFICATION

THESIS

Presented to the faculty of the Graduate School of Engineering & Management of the Air Force Institute of Technology Air University In Partial Fulfillment of the Requirements for the Degree of Master of Science (Computer Science)

David J. Robinson, B. S. 1st Lieutenant, USAF

March 2000

Approved for public release, distribution unlimited.

AFIT/GCS/ENG/00M-22

The views expressed in this thesis are those of the author and do not reflect the official policy or position of the Department of Defense or the U. S. Government.

AFIT/GCS/ENG/00M-22

ACKNOWLEDGMENTS

I would like to sincerely thank my faculty advisor, Maj Scott DeLoach. His guidance, support, relentless badgering, and the fact that he outranked me by quite a bit allowed for the authoring of this quality thesis. In all seriousness, it was truly an honor and a privilege to be his student. His incredible focus and energy was often contagious and made me a better student in spite of myself. Thank you. I would also like to thank Dr. Thomas Hartrum for his advice and guidance throughout the thesis process and Maj Robert Graham for serving on my Thesis committee.

I would like to thank my fellow classmates for making this journey to all

encompassing knowledge bearable and often quite fun. Most importantly, I would like to thank my wife Andrea, whom without, this thesis would have not been written. Her love, support, and willingness to go shopping when I needed to study allowed me to focus on the task at hand. Thank you and I love you.

David J. Robinson

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TABLE OF CONTENTS ACKNOWLEDGMENTS............................................................................................................. II TABLE OF FIGURES .................................................................................................................. V I. INTRODUCTION .......................................................................................................................... 1 1.1 Background........................................................................................................................ 2

1.2 Problem Statement........................................................................................................... 4 1.3 Thesis Overview ................................................................................................................. 5 II. BACKGROUND .......................................................................................................................... 6 2.1 Overview ............................................................................................................................ 6 2.2 Knowledge Representation ................................................................................................ 6 2.3 Architectural Representation ........................................................................................... 12 2.4 Internal Agent Representation ......................................................................................... 36 2.5 Summary .......................................................................................................................... 52 III. APPROACH ............................................................................................................................ 53 3.1 Language Requirements................................................................................................... 54 3.2 Selecting a Language....................................................................................................... 55 3.3 Object Model Definition .................................................................................................. 57 3.4 Language Validation........................................................................................................ 59 3.5 Chapter Summary ............................................................................................................ 63 IV. DESIGN AND IMPLEMENTATION ............................................................................................ 64 4.1 Defining the Requirements............................................................................................... 64 4.2 Review of Existing Languages ......................................................................................... 66 4.3 Language Definition ........................................................................................................ 73 4.4 Object Model Definition .................................................................................................. 85

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4.5 Language Implementation ............................................................................................... 93 4.6 Chapter Summary ............................................................................................................ 96 V. ARCHITECTURAL STYLES ....................................................................................................... 98 5.1 Reactive Agent Architectural Style .................................................................................. 98 5.2 Knowledge Based Architectural Style............................................................................ 105 5.3 Planning Architectural Styles ........................................................................................ 110 5.4 BDI Architectural Style.................................................................................................. 115 5.5 Generic Components...................................................................................................... 119 5.6 Summary ........................................................................................................................ 120 VI. CONCLUSIONS AND FUTURE WORK .................................................................................... 122 6.1 Conclusions.................................................................................................................... 122 6.2 Language Usage ............................................................................................................ 123 6.3 Possible Future Work .................................................................................................... 125 6.4 Thesis Summary ............................................................................................................. 126 REFERENCES ........................................................................................................................... 129

APPENDIX A OCL GRAMMAR [WK99] ....................................................................... 134 APPENDIX B FIGURE 19 OPERATOR DEFINITION .............................................. 137 APPENDIX C LANGUAGE IMPLEMENTATION ...................................................... 138 APPENDIX D REACTIVE STYLE OPERATOR DEFINITION .............................. 152 VITA ............................................................................................................................................ 153

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TABLE OF FIGURES FIGURE 1 GENERIC ELEMENTS OF ADL [AES95] ......................................................................................... 14 FIGURE 2 PRS-CL ARCHITECTURE [PRS99]................................................................................................. 17 FIGURE 3 ARCHITECTURE OF A TYPICAL EXPERT SYSTEM [LS98].................................................................. 22 FIGURE 4 RETSINA ARCHITECTURE [SYC96]............................................................................................. 25 FIGURE 5 PRODIGY EXAMPLE [PROD92]...................................................................................................... 29 FIGURE 6 ACT DIAGRAM EXAMPLE [WM97] ................................................................................................. 32 FIGURE 7 OCL OBJECT MODEL..................................................................................................................... 43 FIGURE 8 Z REPRESENTATION ....................................................................................................................... 46 FIGURE 9 SEMANTIC NETWORK EXAMPLE .................................................................................................... 48 FIGURE 10 FRAME EXAMPLE ......................................................................................................................... 51 FIGURE 11 APPROACH ................................................................................................................................... 53 FIGURE 12 STEP ONE ..................................................................................................................................... 54 FIGURE 13 STEP TWO .................................................................................................................................... 55 FIGURE 14 STEP THREE ................................................................................................................................. 57 FIGURE 15 A GENERIC AGENT ARCHITECTURE ............................................................................................. 58 FIGURE 16 STEP FOUR ................................................................................................................................... 59 FIGURE 17 GENERIC BDI ARCHITECTURE ..................................................................................................... 61 FIGURE 18 REFINED BDI ARCHITECTURE ..................................................................................................... 62 TABLE 1 LANGUAGE REPORT CARD .............................................................................................................. 67 FIGURE 19 REACTIVE ARCHITECTURE ........................................................................................................... 72 FIGURE 20 COMPONENT GROUPING .............................................................................................................. 74 FIGURE 21 AGGREGATION REMOVAL ............................................................................................................ 76 FIGURE 22 INHERITANCE AND AGGREGATION REMOVAL .............................................................................. 79 FIGURE 23 MESSAGEINTERFACE STATEDIAGRAM ........................................................................................ 80

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FIGURE 24 INNER-AGENT CONNECTORS ........................................................................................................ 82 FIGURE 25 OUTER-AGENT CONNECTORS ....................................................................................................... 83 FIGURE 26 BASIC OBJECT MODEL ................................................................................................................. 85 FIGURE 27 OBJECT MODEL REFINEMENT ...................................................................................................... 86 FIGURE 28 COMPONENT ATTRIBUTES ........................................................................................................... 87 FIGURE 29 ATTRIBUTE CLASS ATTRIBUTES .................................................................................................. 89 FIGURE 30 OPERATOR CLASS ATTRIBUTES ................................................................................................... 91 FIGURE 31 >" | "=" | "