A Multiple Viewed Approach To Software Requirements A Dissertation Presented to the Faculty of the School of Engineering and Applied Science (Unofficial copy) University of Virginia In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy ( Computer Science ) by Harry S. Delugach May 1991 ABSTRACT A problem in current requirements development techniques is that the viewpoints (including implicit pre-existing assumptions) of multiple participants must be satisfied by the resulting requirements. Choosing a single language for all participants requires the additional burden of learning the new language and being prepared to overlook some requirements for which the language was not intended. This dissertation proposes a framework and methodology whereby multiple requirements specifications can be produced in several languages of the participants’ own choosing, then translated into a meta-language (that is, a language capable of capturing features of several different requirements languages) in order to analyze their common features. The meta-language of conceptual graphs is used to capture requirements expressed in various conventional requirements development notations. Once translated into conceptual graphs, the set of requirements is analyzed in order to find the most likely counterpart concepts between the partcipants’ requirements specifications. These counterparts represent the overlap between views and form the basis for joining the multiple graphs into one requirements graph. Ambiguous counterparts (i.e., concepts that cannot be distinguished from other concepts) are also identified, guiding the requirements analyst in asking participants further questions about the assumptions that underlie the concepts. i A Multiple-Viewed Approach To Software Requirements Harry S. Delugach Department of Computer Science Computer Science Building Rm 109 University of Alabama in Huntsville Huntsville, AL 35899 U. S. A. Telephone: (205) 895-6614 Electronic mail: [email protected] Table of Contents Table of Contents .................................................................................................i List of Figures.................................................................................................... iv Abbreviations and Symbols ................................................................................... v 1. Introduction....................................................................................................... 1 1.1. Problems With Software Requirements........................................................... 1 1.2. Context of Work......................................................................................... 2 1.3. Multiple Views........................................................................................... 3 1.4. Improving Requirements Development ........................................................... 4 1.5. Outline Of Dissertation................................................................................ 5 2. Views In Software Requirements Development........................................................ 6 2.1. Views in Requirements................................................................................ 6 2.1.1. Purpose Of Using Views.................................................................... 7 2.1.2. Basics Of A View............................................................................. 7 2.1.3. A Participant’s View ......................................................................... 9 2.2. Example Requirements and Assumptions .......................................................12 2.3. Support For A Single View..........................................................................14 2.4. Multiple Viewed Requirements ....................................................................15 2.4.1. Interaction Between Views................................................................15 2.4.2. Support For Multiple Viewed Requirements .........................................16 2.5. The Multiple Viewed Approach....................................................................18 2.6. Summary .................................................................................................18 3. Analyzing Multiple-Viewed Requirements.............................................................20 3.1. Role Of the Requirements Analyst ................................................................21 3.2. Analyzing Overlap Between Views...............................................................23 3.2.1. Identifying Overlap Between Views ....................................................25 3.2.2. Kinds Of Associations ......................................................................26 3.2.3. Association Graph Technique.............................................................28 3.3. General Issues For Multiple Views................................................................35 3.4. Summary .................................................................................................37 4. A Framework and Methodology For Multiple-Viewed Analysis .................................38 4.1. Conceptual Graphs: An Analyst’s Meta-Language ...........................................38 4.2. Definition Of A View.................................................................................40 4.2.1. Domains ........................................................................................40 4.2.2. Requirements Specification ...............................................................42 4.2.3. Requirements Specification Graph ......................................................42 ii 4.2.4. Translation Scheme..........................................................................42 4.2.5. Assumption Graphs..........................................................................43 4.2.6. View .............................................................................................43 4.3. Analyst’s Framework .................................................................................44 4.3.1. Analyst’s Canon..............................................................................44 4.3.2. Analyst’s Requirements Specification Graph.........................................44 4.4. Analysis of Multiple Viewed Requirements ....................................................44 4.4.1. Describing Overlap ..........................................................................45 4.4.2. Analyzing Overlap...........................................................................47 4.5. A Methodology For Multiple Viewed Requirements.........................................49 4.5.1. Methodology Steps ..........................................................................50 4.5.2. Products of Analysis.........................................................................56 4.5.3. Analyst’s View................................................................................56 4.6. General Features Of Approach .....................................................................57 4.7. Summary .................................................................................................58 5. Translating Requirements Into Conceptual Graphs...................................................59 5.1. Entity-Relationship Diagrams ......................................................................60 5.1.1. Example Entity-Relationship Diagram.................................................60 5.1.2. Discussion......................................................................................61 5.2. Data Flow Diagrams...................................................................................61 5.2.1. Example Data Flow Diagram .............................................................62 5.2.2. Discussion......................................................................................63 5.3. State Transition Diagrams ...........................................................................63 5.3.1. Example State Transition Diagram......................................................63 5.3.2. Discussion......................................................................................64 5.4. Requirements Networks (SREM)..................................................................65 5.4.1. Example Requirements Network.........................................................65 5.4.2. Discussion......................................................................................66 5.5. Summary .................................................................................................67 6. A Multiple Viewed Analysis Example...................................................................68 6.1. Analysis: First Association ..........................................................................69 6.2. Analysis: Second Association.......................................................................71 6.3. Analysis: Third Association.........................................................................75 6.4. Results of Analysis ....................................................................................77 6.5. Summary .................................................................................................78 7. Validating Multiple Viewed Analysis....................................................................79 7.1. Overlap Characteristics...............................................................................80 7.2.