Active Rules in Database Systems

This book describes rules for active database systems. It details methodologies, formal specifications, rule analysis, performance analysis, support tools, applications, implementation of active rules in commercial systems and future directions for research.

I Fundamentals.- 1 Introduction.- 1.1 Introduction.- 1.2 Applications.- 1.2.1 Database System Extensions.- 1.2.2 Closed Database Applications.- 1.2.3 Open Database Applications.- 1.2.4 Example Application.- 1.2.5 Conclusions.- 1.3 Knowledge Model.- 1.3.1 Event.- 1.3.2 Condition.- 1.3.3 Action.- 1.4 Execution Model.- 1.5 Management.- 1.6 Conclusion.- 1.7 References.- 2 Architecture of Active Database Systems.- 2.1 Introduction.- 2.2 Degree of Integration.- 2.2.1 Layered Architecture.- 2.2.2 Integrated Architecture.- 2.3 Client-Server Architecture of the Underlying DBMS.- 2.4 Data Model and Programming Language Issues.- 2.5 Rule Specification and Registration.- 2.6 Rule Processing.- 2.6.1 Primitive Event Detector Architecture.- 2.6.2 Composite Event Detector Architecture.- 2.6.3 Event Consumption and Logging.- 2.6.4 Guarded Events, Light-Weight Vs. Heavy-Weight Events.- 2.6.5 Rule Scheduling.- 2.6.6 Transaction Models.- 2.6.7 Rule Execution.- 2.7 Recovery.- 2.8 Conclusion.- 2.9 References.- Advanced Topics.- 3 Rule Analysis.- 3.1 Introduction.- 3.2 Termination Analysis.- 3.2.1 Triggering and Activation Graphs.- 3.2.2 Building the Activation Graph.- 3.2.3 Termination with Priorities.- 3.3 Confluence Analysis.- 3.3.1 Analyzing Commutativity.- 3.3.2 Confluence with Priorities.- 3.4 Conclusion.- 3.5 References.- 4 Optimization.- 4.1 Introduction.- 4.2 Optimizing Single Rules.- 4.2.1 Exploiting Parameters.- 4.2.2 Moving Constraints.- 4.3 Optimizing Multiple Rules.- 4.4 Conclusion.- 4.5 Acknowledgments.- 4.6 References.- 5 Monitoring Complex Rule Conditions.- 5.1 Introduction.- 5.2 Incremental Evaluation Techniques.- 5.3 Differencing Relational Expressions.- 5.4 Monitoring Active Rule Conditions in AMOS.- 5.4.1 Rules in AMOSQL.- 5.4.2 Rule Compilation.- 5.5 Partial Differencing.- 5.5.1 Breadth-First Propagation.- 5.5.2 Differencing Base Relations.- 5.5.3 Partial Differencing of Views.- 5.6 Conclusion.- 5.7 References.- 6 Performance Assessment.- 6.1 Introduction.- 6.2 Performance-Critical Aspects of Active Database Systems.- 6.2.1 Performance of Active Database Applications.- 6.2.2 Performance-Critical Aspects of Active Database Management Systems.- 6.3 Performance Measurement of Active Database Management Systems.- 6.3.1 Benchmark Design.- 6.3.2 Factors and Modes.- 6.3.3 Results for SAMOS.- 6.3.4 Lessons and Observation.- 6.4 Steps Towards Performance Improvement of ADBMS’s.- 6.4.1 Optimizing ADBMS Implementations.- 6.4.2 Tuning ADBMS Applications.- 6.5 Related Work.- 6.6 Conclusion.- 6.7 Acknowledgments.- 6.8 References.- 7 Tool Support.- 7.1 Introduction.- 7.2 Analysis and Design Support.- 7.2.1 Graphical Description Tools.- 7.2.2 Validation Tools.- 7.2.3 Verification Tools.- 7.3 Implementation Support.- 7.3.1 Tracing Tools.- 7.4 Maintenance Support.- 7.4.1 Browsers.- 7.4.2 Evolution Support Tools.- 7.4.3 Explanation Tools.- 7.4.4 Measurement Tools.- 7.5 From Isolated Tools to Integrated Environments.- 7.6 Conclusion.- 7.7 References.- 8 ECA Functionality in a Distributed Environment.- 8.1 Introduction.- 8.1.1 Challenges.- 8.1.2 Dimensions Revisited.- 8.1.3 Outline of the Chapter.- 8.2 Two Views of the Networked Active Database System.- 8.3 Applications for ECA Rules in Distributed Environments.- 8.3.1 Service View.- 8.3.2 Communications Channel View.- 8.4 How Distribution Affects the Knowledge Model.- 8.5 How Distribution Affects the Execution Model.- 8.5.1 Architectural Model of the Network System.- 8.5.2 Event Detection.- 8.5.3 Scheduling.- 8.5.4 Condition Evaluation and Action Execution.- 8.6 Classification of Existing Approaches.- 8.7 Conclusion.- 8.8 References.- 9 Comparing Deductive and Active Databases.- 9.1 Introduction.- 9.1.1 Main Classes of Rule-Based Database Systems.- 9.1.2 Some Pragmatic Issues to Confront.- 9.1.3 Possible Directions for Unification Efforts.- 9.1.4 Main Requirements for Unification Efforts.- 9.2 Deductive Rules Compared with Active Rules.- 9.2.1 Semantic Dissimilarities.- 9.2.2 Syntactic Similarities.- 9.2.3 A Dimensional Analysis of Deductive Rule Sets.- 9.3 Bringing Deductive and Active Rules Together.- 9.3.1 Issues and Targets.- 9.3.2 Basic Research Stances.- 9.4 A Brief Survey of Proposals for Languages with Deductive and Active Capabilities.- 9.4.1 The Widom Spectrum.- 9.4.2 DDB-Oriented Proposals.- 9.4.3 ADB-Oriented Proposals.- 9.5 Conclusion.- 9.6 Acknowledgments.- 9.7 References.- III Systems.- 10 Active Database Features in SQL3.- 10.1 Introduction.- 10.2 Triggers in SQL3.- 10.2.1 Constraints in SQL3.- 10.2.2 Overview of SQL3 Triggers.- 10.2.3 Execution Model for Triggers in SQL3.- 10.2.4 Discussion of SQL3’s Execution Model.- 10.3 Examples.- 10.4 Comparison of SQL3 Triggers to the Active Database Framework.- 10.4.1 Knowledge Model.- 10.4.2 Execution Model.- 10.4.3 Management.- 10.5 Conclusion.- 10.6 References.- 11 Ariel.- 11.1 Introduction.- 11.2 The Ariel Query and Rule Languages.- 11.2.1 Semantics of Rule Execution.- 11.3 Examples.- 11.4 Architectural Overview.- 11.4.1 The Discrimination Network.- 11.4.2 The Rule Execution Monitor.- 11.5 System Properties and Relationship to Other Work.- 11.6 Conclusion.- 11.7 References.- 12 SAMOS.- 12.1 Introduction.- 12.2 ECA Rules in SAMOS.- 12.3 The SAMOS Prototype.- 12.3.1 Defining Rules and Events.- 12.3.2 Rule Processing.- 12.3.3 Evaluation of the SAMOS Prototype.- 12.3.4 An Example.- 12.4 Future Directions.- 12.5 Conclusion.- 12.6 Acknowledgments.- 12.7 References.- 13 EXACT: An Approach to Coping with Heterogeneous Rule Execution Models.- 13.1 Introduction.- 13.2 The Knowledge Model.- 13.3 The Execution Model.- 13.4 Some Examples.- 13.4.1 Dynamic Display Support.- 13.4.2 Relationship Semantic Support.- 13.4.3 Integrity Constraint Maintenance.- 13.5 Conclusion.- 13.6 References.- 14 REACH.- 14.1 Introduction.- 14.2 The OpenOODB Platform.- 14.3 REACH Goals, Design Principles, and Implementation Decisions.- 14.3.1 Event Detection and Composition.- 14.3.2 Rule Execution and Coupling Modes.- 14.3.3 Events: Scoping, Composition, and Parameter Passing.- 14.4 REACH Environment and Tools.- 14.4.1 Modeling Rules with OMT+.- 14.4.2 Rule Language REAL.- 14.4.3 Administration Tools.- 14.5 Summary of Features.- 14.6 Conclusion.- 14.7 Acknowledgments.- 14.8 References.- 15 NAOS.- 15.1 Introduction.- 15.2 Rules in NAOS.- 15.2.1 Rules and O2.- 15.2.2 Rule Definition.- 15.2.3 Event Part.- 15.2.4 Condition.- 15.2.5 Action.- 15.2.6 Event-Condition-Action Binding.- 15.2.7 Management of Rules.- 15.2.8 Conclusion.- 15.3 Event Types.- 15.3.1 Primitive Event Types.- 15.3.2 Composite Event Types.- 15.3.3 Validity Time Interval.- 15.3.4 With Clause.- 15.4 Rule Execution.- 15.4.1 Coupling Modes.- 15.4.2 Multiple Rule Execution.- 15.4.3 Cascading Execution.- 15.4.4 Net Effect Policy and Error Handling.- 15.4.4 Asynchronous Rule Execution.- 15.4.5 Conclusion.- 15.5 Implementation.- 15.5.1 Analyser.- 15.5.2 Constructor.- 15.5.3 Event Detectors and Event Manager.- 15.5.4 Executor.- 15.6 Conclusion.- 15.7 Acknowledgments.- 15.8 References.- 16 PFL: An Active Functional DBPL.- 16.1 Introduction.- 16.2 PFL.- 16.2.1 Types.- 16.2.2 Expressions and Functions.- 16.2.3 Bulk Data.- 16.2.4 Queries and Transactions.- 16.2.5 User-Defined Events.- 16.3 The Active Subsystem.- 16.3.1 Primitive Events.- 16.3.2 ECA rules.- 16.3.3 Execution Model.- 16.3.4 Abort Handling.- 16.4 Conclusion.- 16.5 Acknowledgments.- 16.6 References.- 17 Chimera: A Language for Designing Rule Applications.- 17.1 Introduction.- 17.2 The Chimera Model and Language.- 17.2.1 The Chimera Trigger Language.- 17.2.2 Events.- 17.2.3 Conditions.- 17.2.4 Actions.- 17.2.5 Execution Model.- 17.3 Chimera as a Conceptual Specification Language.- 17.3.1 Generation of Chimera Triggers from High-Level Declarative Specifications.- 17.3.2 Chimera Rule Analysis and Debugging.- 17.3.3 Implementation of Chimera on Top of Commercial Systems.- 17.4 Acknowledgments.- 17.5 References.- 18 RAP: The ROCK & ROLL Active Programming System.- 18.1 Introduction.- 18.2 ROCK & ROLL.- 18.2.1 Data Model.- 18.2.2 ROCK.- 18.2.3 ROLL.- 18.2.4 Queries.- 18.3 Knowledge Model.- 18.3.1 Event Language and Event Model.- 18.3.2 Condition Model.- 18.3.3 Action Model.- 18.4 Execution Model.- 18.5 Implementation.- 18.6 Conclusion.- 18.7 References.- IV Applications.- 19 Database Internal Applications.- 19.1 Introduction.- 19.2 ECA Rules for Integrity Maintenance.- 19.2.1 ECA Rules for Checking Constraints.- 19.2.2 ECA Rules for Constraint Repair.- 19.2.3 ECA Rules for Non Standard Constraint Checking.- 19.3 ECA Rules for Views and Data Integration.- 19.3.1 ECA Rules for Database Views.- 19.3.2 ECA Rules for Data Integration.- 19.4 ECA Rules for Advanced Transactions and Updates.- 19.5 Conclusion.- 19.6 References.- 20 Active Database Systems: Expectations, Commercial Experience, and Beyond.- 20.1 Introduction.- 20.2 Expectations of Active DBMS’s.- 20.2.1 Passive Vs. Active Database Applications.- 20.2.2 Advantages of Active Database Systems.- 20.2.3 Application Domains for Active DBMS’s.- 20.2.4 Applications Implementing System Extensions.- 20.2.5 Applications Implementing Business Rules.- 20.3 Realities of Active Database Systems.- 20.3.1 Limitations of SQL Trigger Systems.- 20.3.2 Administration Tools and Design Methodologies.- 20.3.3 Performance.- 20.4 Optimizing Active Applications.- 20.4.1 Relaxing of Constraints.- 20.4.2 Optimizing a Relational Schema.- 20.4.3 Select Lower Isolation Modes.- 20.4.4 Chopping Transactions.- 20.4.5 Choosing the Instants for Rule Processing.- 20.4.6 Detached Processing of Triggers.- 20.5 Perspectives.- 20.5.1 Extensions of SQL Trigger Systems.- 20.5.2 Administration Tools and Design Methodologies.- 20.5.3 Optimization of Triggers.- 20.6 Conclusion.- 20.7 Acknowledgments.- 20.8 References.- 21 Active Real-Time Database Systems.- 21.1 Introduction.- 21.2 Real-Time Database Systems.- 21.2.1 What Is a Real-Time System?.- 21.2.2 Categorization of Real-Time Systems.- 21.2.3 The Role of ARTDBS in Real-Time Systems.- 21.2.4 Real-Time Transaction Characteristics.- 21.2.5 Temporal Scope.- 21.3 Applications.- 21.3.1 Cooperative Distributed Navigation Systems.- 21.3.2 Network Management.- 21.4 System Aspects.- 21.4.1 Execution Model: Coupling Modes.- 21.4.2 Execution Model: Action Scheduling and Execution.- 21.4.3 Event Detection.- 21.4.4 Rule Triggering.- 21.4.5 Condition Evaluation.- 21.4.6 ARTDBS Prototypes and Platforms.- 21.5 Conclusion.- 21.6 Acknowledgments.- 21.7 References.- V Summary.- 22 Summary.- 22.1 Introduction.- 22.2 Topic-Based Summaries.- 22.2.1 Architectures.- 22.2.2 Event Detection.- 22.2.3 Specification of Active Systems.- 22.2.4 Rule Analysis.- 22.2.5 Rule Optimization.- 22.2.6 Condition Monitoring/Production Rule Algorithms.- 22.2.7 Performance Assessment/Improvement.- 22.2.8 Design Methods.- 22.2.9 Tool Support.- 22.2.10 Distribution.- 22.2.11 Applications.- 22.2.12 Standards.- 22.3 References.