Flexible Software Design Systems Development for Changing Requirements

To avoid burdensome maintenance costs developers must rely on a system's flexibility. This handbook demonstrates the design principles and techniques that enable the design of software that empowers business staff to make functional changes to their systems with little or no professional IT intervention.

A developer's knowledge of a computing system's requirements is necessarily imperfect because organizations change. Many requirements lie in the future and are unknowable at the time the system is designed and built. To avoid burdensome maintenance costs developers must therefore rely on a system's ability to change gracefully-its flexibility. Flexible Software Design: Systems Development for Changing Requirements demonstrates the design principles and techniques that enable the design of software that empowers business staff to make functional changes to their systems with little or no professional IT intervention.The book concentrates on the design aspects of system development, the area with the most flexibility leverage. Divided into four parts, the text begins by introducing the fundamental concepts of flexibility, explaining the reality of imperfect knowledge and how development participants must change their thinking to implement flexible software. The second part covers design guidelines, stable identifiers, stable information structures, the Generic Entity Cloud concept, and regulatory mechanisms that give business staff control over system modifications. Part three relates strategic information systems planning to flexible systems. It examines the elicitation of requirements and the relevance of agile methods in a flexible systems environment. It also discusses practical aspects of stable identifier design and compares the testing of traditional and flexible software. In part four, the book concludes with details of the flexible UniverSIS system and an explanation of the applications and extensions of the Generic Entity Cloud tools.The combination of smart design and smart work offered in Flexible Software Design can materially benefit your organization by radically reducing the systems maintenance burden.

INTRODUCTION TO FLEXIBILITYThe Serious Problems with IT Today The Industrywide Maintenance Problem What Is Wrong with Nonflexible Systems? Two Cautionary TalesThe Typical IT Environment: No Time to Do It Right - Timeto Do It Over!Summary The Reality of Imperfect Knowledge Flexibility: An Improved Way of ThinkingWhat Is Flexible Software? Change or Die Evolution of Flexibility IT Misconceptions and Flexibility ConceptsSummary Outcome, Not MethodologyMired in Methodology Software Engineering ShiftsSummary Realignment of Roles Roles and Responsibilities in Traditional and FlexibleDevelopment Flexibility AttitudesSummary UniverSIS: a Flexible System BackgroundSuccess StoriesTwo System Features Summary WHAT IS REQUIRED TO ACHIEVE FLEXIBILITYGuidelines for Flexible Software Design Treat "Design" as a NounDesign for the Long Haul Observe Consistent Standards Use N-Tiered Architecture Employ Individual Data Objects Take Advantage of Reusable Logic Code General-Purpose Routines Recognize the Limits of Flexibility Summary The Importance of Stable Identifiers Information-Free Stable Identifiers Types of Unstable Identifiers Identifiers and the Relational Data Model Summary Regulation: Managing Artificial LimitsBusiness Rules as Artificial LimitsGeneral Regulation of Business RulesCardinality Regulation: Variable Cardinality, Many-to-ManyAssociations Summary Appendix: Using Regulation to Make a Flexible SystemAppendix: Business Rules ManifestoStable Information StructuresStructure/Process Differentiation: Generic StructuresRecursive RelationshipsTyping and Generic EntitiesRecognizing Certain Forms of DataBottom-Up Derivation of Generic Entities Summary The Generic-Entity Cloud (GEC)What Is a Generic-Entity Cloud?Three-Node Generic-Entity CloudExternalsSix-Node Generic-Entity Cloud GECs, Attributes, and Flexibility Externals Connected to Generic-Type NodeSummary HOW TO DESIGN FLEXIBLE SOFTWARE SYSTEMSFlexibility and Strategic Systems PlanningThe Myth of the Isolated SystemTraditional Planning Approach Stable Enterprise ModelStrategic Systems Planning for FlexibilitySummary Requirements Determination for Flexible SystemsMyth of Perfect Knowledge Definition of Effective RequirementsIdentifying Dynamic RequirementsAgile Methodologies Summary System Design with an Eye on FlexibilityStructure-Oriented Techniques for Flexible Software Design Process-Oriented Techniques for Flexible Software DesignSummary Appendix: Dynamic Condition Search Program Listing (in Java)Implementing Stable Identifiers The Basic Rule Applying the Basic Rule Circumvention Paths - Back to the Beginning Summary Testing and Maintenance of Flexible Software Errors Encountered in Testing Two Phases of Testing Summary Identifying, Managing, and Acquiring Quality FlexibleSoftwareFlexibility and Quality Managing System Development/Acquisition to Achieve Flexibility Procuring Flexible Software Summary FLEXIBILITY: DELVING DEEPERA Closer Look at UniverSIS Navigation and SecurityDocumentsRequired Admission Credentials Contact ManagementCorrespondenceCorrespondence Tracks Selected-ID Lists TestsEmployee Profile Grades Summary Evaluator: a Flexible Tool for Maintaining Business RulesRecord RulesEvaluateEvaluator: the DetailsWorking through ExamplesSummary Tuition-Remission Case Study: Traditional versusFlexible Traditional Approach Flexible Approach Comparison of Traditional and Flexible Approaches Summary Regulatory GECs (Generic Entity Clouds)Attached versus Detached Regulation GEC Validation Tables Generic Validation Table GECsWhen to Use Attached or Detached Regulation Value-to-Value Translation Summary GEC Applications and Extensions Developing a GEC GEC with Business Rules Multi-Ring GECThe Atomic GEC SubGECsSummary GEC AidsThe GECAnalyzer The GECBuilder The GECPhazer Summary Appendix A: Bibliography and References