Delta-4 is a 5-nation, 13-partner project that has been investigating the achievement of dependability in open distributed systems, including real-time systems. This book describes the design and validation of the distributed fault-tolerant architecture developed within this project. The key features of the Delta-4 architecture are: (a) a distributed object-oriented application support environment; (b) built-in support for user-transparent fault tolerance; (c) use of multicast or group communication protocols; and (d) use of standard off the-shelf processors and standard local area network technology with minimum specialized hardware. The book is organized as follows: The first 3 chapters give an overview of the architecture's objectives and of the architecture itself, and compare the proposed solutions with other approaches. Chapters 4 to 12 give a more detailed insight into the Delta-4 architectural concepts. Chapters 4 and 5 are devoted to providing a firm set of general concepts and terminology regarding dependable and real-time computing. Chapter 6 is centred on fault-tolerance techniques based on distribution. The deillegalscription of the architecture itself commences with a deillegalscription of the Delta-4 application support environment (Deltase) in chapter 7. Two variants of the architecture - the Delta-4 Open System Architecture (OSA) and the Delta-4 Extra Performance Architecture (XPA) - are described respectively in chapters 8 and 9. Both variants of the architecture have a common underlying basis for dependable multicasting, i. e.|This book describes the design and validation of the Delta-4 distributed fault-tolerant architecture. The architecture features a dependable communication system using standard local area network technology, a distributed object-oriented application support environment, use of multicast or group communication protocols, and built-in support for user-transparent fault-tolerance.
1. Requirements and Objectives.- 1.1. Fields of Application.- 1.2. Architectural Attributes.- 2. Overview of the Architecture.- 2.1. Dependability and Real-Time Concepts.- 2.2. Dependability and Real-Time in Delta-4.- 2.3. Architectural Sub-Systems.- 2.4. Software Environment and Management Issues.- 2.5. Validation.- 3. Comparison with other Approaches.- 3.1. Commercial Fault-Tolerance Techniques.- 3.2. Comparison of Approaches by Concept/Technique.- 3.3. Comparison of Approaches by Target System Characteristics.- 3.4. Case Studies.- 3.5. Conclusion.- 4. Dependability Concepts.- 4.1. Basic Definitions.- 4.2. On the Introduction of Dependability as a Generic Concept.- 4.3. On System Function, Behavior, Structure and Specification.- 4.4. The Impairments to Dependability.- 4.5. The Means for Dependability.- 4.6. The Attributes of Dependability.- 5. Real-Time Concepts.- 5.1. Concepts and Definitions.- 5.2. Delta-4 Approach to Real-Time.- 5.3. Real-Time Communications Protocols.- 5.4. Summary of Real-Time System Requirements.- 5.5. Conclusions.- 6. Distributed Fault-Tolerance.- 6.1. Related Work.- 6.2. Node Hardware Characteristics.- 6.3. Models of Distributed Computation.- 6.4. Replicated Software Components.- 6.5. Active Replication.- 6.6. Passive Replication.- 6.7. Semi-Active Replication.- 6.8. Group Management and Fault Treatment.- 6.9. Communications Support.- 6.10. Conclusion.- 7. Delta-4 Application Support Environment (Deltase).- 7.1. Purpose and Background.- 7.2. Computational Model.- 7.3. Engineering Model.- 7.4. Deltase Support for Distributed Fault-Tolerance.- 7.5. Engineering Support for Fault-Tolerance.- 7.6. Dependable Databases.- 8. Open System Architecture (OSA).- 8.1. Multipoint Communication System (MCS).- 8.2. System Administration.- 9. Extra Performance Architecture (XPA).- 9.1. Objectives and Definitions.- 9.2. Overview.- 9.3. Real-time and Performance.- 9.4. Dependability and Computational Models.- 9.5. Support for Distributed Real-Time Computing.- 9.6. XPA as an Integrated Machine.- 9.7. System Administration.- 10. The Atomic Multicast protocol (AMp).- 10.1. Notions about Reliable Group Communication.- 10.2. Related Work.- 10.3. System Architecture.- 10.4. Summary of xAMp Services.- 10.5. The Abstract Network.- 10.6. Two-Phase Accept Protocol.- 10.7. Performance and Real-Time.- 10.8. Implementation Issues.- 11. Fail-Silent Hardware for Distributed Systems.- 11.1. Fail-Silent Node Models.- 11.2. A Comparative Evaluation.- 11.3. Concluding Remarks.- 12. Input/Output: Interfacing the Real World.- 12.1. Inter-working with non-Delta-4 systems.- 12.2. Inter-working with the Physical Environment.- 12.3. Summary.- 13. Security.- 13.1. Principles of Intrusion-Tolerance.- 13.2. Fragmentation-Scattering Applied to File Archiving.- 13.3. Intrusion-Tolerant Security Server.- 13.4. Selection and Implementation of an Authorization Policy.- 13.5. Future Extensions.- 14. Software-Fault Tolerance.- 14.1. A Brief History — the State of the Art.- 14.2. Software-Fault Tolerance for Delta-4.- 14.3. Support Mechanisms and Features.- 14.4. Specifying Software Components for Software-fault Tolerance — Tradeoffs in an Object Environment.- 14.5. Concluding Remarks.- 15. Validation.- 15.1. Overview.- 15.2. Protocol Validation.- 15.3. Fault Injection.- 15.4. Dependability Evaluation.- 15.5. Software Reliability.- Annexes.- A. Safety-Critical and Safety-Related Systems.- B. Deterministic UNIX.- C. Statistical Effects with Schedules of many Activities.- D. Assigning Precedence Parameters.- E. Formal Failure Mode Assumptions.- F. Assumption Coverage.- G. Propagate-before-Validate Error Processing Technique.- H. Interface between XPA and OSA.- I. Timing Characteristics of Preemption Points.- J. Formal Presentation of AMp.- K. Models for the Representation of Reactive Systems.- L. Service Specifications.- M. Co-existence with non-Delta-4 Stations on the same LAN.- Glossary of Abbreviations.- References.- Author Affiliations.- The Delta-4 Consortium.
This book describes the design philosophy and concepts of a novel distributed fault-tolerant architecture developed by the Delta-4 project, a five-nation, thirteen-partner project investigating the achievement of dependability in open distributed systems, including real-time systems. The architecture features a dependable communication system using standard local area network technology, a distributed object-oriented application support environment, use of multicast or group communication protocols, and built-in support for user-transparent fault-tolerance. The book opens with an overview of the architecture and its objectives, then describes the concepts of de- pendability, real-time and distributed fault-tolerance and the design of each of the major architectural components, including the Delta-4 applications support environment and the open and extra performance variants of the architecture.
Work is described in the field of security, on intrusion-tolerance and tolerance of software design faults by diversified design. Finally, there is an overview of the validation activities carried out on the architecture. The book gives an insight into state-of-the-art techniques for providing both dependable and real-time service in distributed systems.
1. Requirements and Objectives.- 1.1. Fields of Application.- 1.2. Architectural Attributes.- 2. Overview of the Architecture.- 2.1. Dependability and Real-Time Concepts.- 2.2. Dependability and Real-Time in Delta-4.- 2.3. Architectural Sub-Systems.- 2.4. Software Environment and Management Issues.- 2.5. Validation.- 3. Comparison with other Approaches.- 3.1. Commercial Fault-Tolerance Techniques.- 3.2. Comparison of Approaches by Concept/Technique.- 3.3. Comparison of Approaches by Target System Characteristics.- 3.4. Case Studies.- 3.5. Conclusion.- 4. Dependability Concepts.- 4.1. Basic Definitions.- 4.2. On the Introduction of Dependability as a Generic Concept.- 4.3. On System Function, Behavior, Structure and Specification.- 4.4. The Impairments to Dependability.- 4.5. The Means for Dependability.- 4.6. The Attributes of Dependability.- 5. Real-Time Concepts.- 5.1. Concepts and Definitions.- 5.2. Delta-4 Approach to Real-Time.- 5.3. Real-Time Communications Protocols.- 5.4. Summary of Real-Time System Requirements.- 5.5. Conclusions.- 6. Distributed Fault-Tolerance.- 6.1. Related Work.- 6.2. Node Hardware Characteristics.- 6.3. Models of Distributed Computation.- 6.4. Replicated Software Components.- 6.5. Active Replication.- 6.6. Passive Replication.- 6.7. Semi-Active Replication.- 6.8. Group Management and Fault Treatment.- 6.9. Communications Support.- 6.10. Conclusion.- 7. Delta-4 Application Support Environment (Deltase).- 7.1. Purpose and Background.- 7.2. Computational Model.- 7.3. Engineering Model.- 7.4. Deltase Support for Distributed Fault-Tolerance.- 7.5. Engineering Support for Fault-Tolerance.- 7.6. Dependable Databases.- 8. Open System Architecture (OSA).- 8.1. Multipoint Communication System (MCS).- 8.2. System Administration.- 9. Extra PerformanceArchitecture (XPA).- 9.1. Objectives and Definitions.- 9.2. Overview.- 9.3. Real-time and Performance.- 9.4. Dependability and Computational Models.- 9.5. Support for Distributed Real-Time Computing.- 9.6. XPA as an Integrated Machine.- 9.7. System Administration.- 10. The Atomic Multicast protocol (AMp).- 10.1. Notions about Reliable Group Communication.- 10.2. Related Work.- 10.3. System Architecture.- 10.4. Summary of xAMp Services.- 10.5. The Abstract Network.- 10.6. Two-Phase Accept Protocol.- 10.7. Performance and Real-Time.- 10.8. Implementation Issues.- 11. Fail-Silent Hardware for Distributed Systems.- 11.1. Fail-Silent Node Models.- 11.2. A Comparative Evaluation.- 11.3. Concluding Remarks.- 12. Input/Output: Interfacing the Real World.- 12.1. Inter-working with non-Delta-4 systems.- 12.2. Inter-working with the Physical Environment.- 12.3. Summary.- 13. Security.- 13.1. Principles of Intrusion-Tolerance.- 13.2. Fragmentation-Scattering Applied to File Archiving.- 13.3. Intrusion-Tolerant Security Server.- 13.4. Selection and Implementation of an Authorization Policy.- 13.5. Future Extensions.- 14. Software-Fault Tolerance.- 14.1. A Brief History - the State of the Art.- 14.2. Software-Fault Tolerance for Delta-4.- 14.3. Support Mechanisms and Features.- 14.4. Specifying Software Components for Software-fault Tolerance - Tradeoffs in an Object Environment.- 14.5. Concluding Remarks.- 15. Validation.- 15.1. Overview.- 15.2. Protocol Validation.- 15.3. Fault Injection.- 15.4. Dependability Evaluation.- 15.5. Software Reliability.- Annexes.- A. Safety-Critical and Safety-Related Systems.- B. Deterministic UNIX.- C. Statistical Effects with Schedules of many Activities.- D. Assigning Precedence Parameters.- E. Formal Failure Mode Assumptions.- F. AssumptionCoverage.- G. Propagate-before-Validate Error Processing Technique.- H. Interface between XPA and OSA.- I. Timing Characteristics of Preemption Points.- J. Formal Presentation of AMp.- K. Models for the Representation of Reactive Systems.- L. Service Specifications.- M. Co-existence with non-Delta-4 Stations on the same LAN.- Glossary of Abbreviations.- References.- Author Affiliations.- The Delta-4 Consortium.
Inhaltsverzeichnis
1. Requirements and Objectives.- 1.1. Fields of Application.- 1.2. Architectural Attributes.- 2. Overview of the Architecture.- 2.1. Dependability and Real-Time Concepts.- 2.2. Dependability and Real-Time in Delta-4.- 2.3. Architectural Sub-Systems.- 2.4. Software Environment and Management Issues.- 2.5. Validation.- 3. Comparison with other Approaches.- 3.1. Commercial Fault-Tolerance Techniques.- 3.2. Comparison of Approaches by Concept/Technique.- 3.3. Comparison of Approaches by Target System Characteristics.- 3.4. Case Studies.- 3.5. Conclusion.- 4. Dependability Concepts.- 4.1. Basic Definitions.- 4.2. On the Introduction of Dependability as a Generic Concept.- 4.3. On System Function, Behavior, Structure and Specification.- 4.4. The Impairments to Dependability.- 4.5. The Means for Dependability.- 4.6. The Attributes of Dependability.- 5. Real-Time Concepts.- 5.1. Concepts and Definitions.- 5.2. Delta-4 Approach to Real-Time.- 5.3. Real-Time Communications Protocols.- 5.4. Summary of Real-Time System Requirements.- 5.5. Conclusions.- 6. Distributed Fault-Tolerance.- 6.1. Related Work.- 6.2. Node Hardware Characteristics.- 6.3. Models of Distributed Computation.- 6.4. Replicated Software Components.- 6.5. Active Replication.- 6.6. Passive Replication.- 6.7. Semi-Active Replication.- 6.8. Group Management and Fault Treatment.- 6.9. Communications Support.- 6.10. Conclusion.- 7. Delta-4 Application Support Environment (Deltase).- 7.1. Purpose and Background.- 7.2. Computational Model.- 7.3. Engineering Model.- 7.4. Deltase Support for Distributed Fault-Tolerance.- 7.5. Engineering Support for Fault-Tolerance.- 7.6. Dependable Databases.- 8. Open System Architecture (OSA).- 8.1. Multipoint Communication System (MCS).- 8.2. System Administration.- 9. Extra Performance Architecture (XPA).- 9.1. Objectives and Definitions.- 9.2. Overview.- 9.3. Real-time and Performance.- 9.4. Dependability and Computational Models.- 9.5. Support for Distributed Real-Time Computing.- 9.6. XPA as an Integrated Machine.- 9.7. System Administration.- 10. The Atomic Multicast protocol (AMp).- 10.1. Notions about Reliable Group Communication.- 10.2. Related Work.- 10.3. System Architecture.- 10.4. Summary of xAMp Services.- 10.5. The Abstract Network.- 10.6. Two-Phase Accept Protocol.- 10.7. Performance and Real-Time.- 10.8. Implementation Issues.- 11. Fail-Silent Hardware for Distributed Systems.- 11.1. Fail-Silent Node Models.- 11.2. A Comparative Evaluation.- 11.3. Concluding Remarks.- 12. Input/Output: Interfacing the Real World.- 12.1. Inter-working with non-Delta-4 systems.- 12.2. Inter-working with the Physical Environment.- 12.3. Summary.- 13. Security.- 13.1. Principles of Intrusion-Tolerance.- 13.2. Fragmentation-Scattering Applied to File Archiving.- 13.3. Intrusion-Tolerant Security Server.- 13.4. Selection and Implementation of an Authorization Policy.- 13.5. Future Extensions.- 14. Software-Fault Tolerance.- 14.1. A Brief History - the State of the Art.- 14.2. Software-Fault Tolerance for Delta-4.- 14.3. Support Mechanisms and Features.- 14.4. Specifying Software Components for Software-fault Tolerance - Tradeoffs in an Object Environment.- 14.5. Concluding Remarks.- 15. Validation.- 15.1. Overview.- 15.2. Protocol Validation.- 15.3. Fault Injection.- 15.4. Dependability Evaluation.- 15.5. Software Reliability.- Annexes.- A. Safety-Critical and Safety-Related Systems.- B. Deterministic UNIX.- C. Statistical Effects with Schedules of many Activities.- D. Assigning Precedence Parameters.- E. Formal Failure Mode Assumptions.- F. Assumption Coverage.- G. Propagate-before-Validate Error Processing Technique.- H. Interface between XPA and OSA.- I. Timing Characteristics of Preemption Points.- J. Formal Presentation of AMp.- K. Models for the Representation of Reactive Systems.- L. Service Specifications.- M. Co-existence with non-Delta-4 Stations on the same LAN.- Glossary of Abbreviations.- References.- Author Affiliations.- The Delta-4 Consortium.
This book describes the design and validation of the Delta-4 distributed fault-tolerant architecture. The architecture features a dependable communication system using standard local area network technology, a distributed object-oriented application support environment, use of multicast or group communication protocols, and built-in support for user-transparent fault-tolerance.
