Open Distributed Systems

Jon Crowcroft

• Preface
  • Theme and Purpose
  • Approach
  • Object Oriented Models
  • Open Distributed Systems
  • Distributed Operating Systems
  • Model for Open Distributed Systems
    • The Standards Process
  • Intended Usage
  • Organization
• Contents
• List of Figures
• List of Tables
  • Acknowledgements
• What are Open Distributed Systems and For What?
  • Introduction
  • The Viewpoints
  • Transparencies
  • Central Operating System Services
    • System Interfaces
    • Distributed Operating Systems
  • Communications Support
    • Users
    • Operating System Facilities
    • Operating System Support
  • Open Communications.
  • Open Distributed Systems
  • Objects as a modeling concept.
    • A Worked Example
    • Objects and Processes
    • Objects and Distribution.
  • Summary
  • Exercises
• Modules, Communication and Concurrency
  • Introduction
  • Addressing, Naming and Routing
    • Worked Example of Name Spaces
  • Concurrent Systems
    • Time Sequence Diagrams
  • Interleaving and true parallelism
    • Interleaving
    • Atomicity
    • Scheduling
  • Shared Resources - Problems with Concurrency
    • Deadlock
    • Livelock
    • Fairness
  • Mutual Exclusion
  • Consumers, Producers and Critical Regions
  • Monitors, Semaphores and Rendezvous
    • Semaphores
    • Monitor
    • The Ada Rendezvous
  • Distributed System and Concurrency
    • Shared Memory
    • Message Passing
  • Worked Example of Networked Windows
    • Portability and Network Window Protocols
    • Window Managers
  • Remote Procedure Call
    • RPC and Threads
    • Interface Compiling
    • ROS and ASN.1
    • Naming, Location and Binding
    • Scaling of Naming/Binding mechanisms.
    • ANSA Trader
    • Directory Services
    • Recursion and Call Back
    • Concurrency Control
    • Multicast
    • Upcalls
    • Buffering Schemes
  • Summary
  • Exercises
• Real Time and Reliable Systems
  • Introduction
    • Some Definitions.
    • How things fail
  • The Object Model and Fault Transparency
    • Examples
  • Conventional Hardware and Software Reliability
    • Example
  • Software in distributed systems
  • Contracting for Reliability
  • Analysing Timing Constraints
    • Watchdog Timers
    • Synchronisation Mechanisms
  • Transactions
    • Example
    • Concurrency Control
      • Locks
  • Timestamps
    • Optimistic Concurrency Control
    • Recovery mechanisms
      • Failures
    • A Commit log
    • 2 Phase Commits
  • More about Multiple readers/single writer and the Object Model
  • Commitment, Concurrency and Recovery - CCR
  • Fault Tolerance
    • Replication/Redundancy
    • Nested Transactions
    • Version Management
    • Replication
  • Object Migration
  • Exception handling
    • Examples
  • Summary
  • Exercises
• The Nature of Security
  • Threats and Protection
  • Access Control and Authentication
  • Authorization
  • Access Control Schemes
  • Trust in a Secure System
  • General Models of Computer Security
    • Multi-Level Security
    • Commercial Security
  • Cryptography
    • Secret Key (or Symmetric) Technique
    • Public Key (or Asymmetric) Technique
    • Key Distribution
    • Blocking
  • Key Distribution
  • Practical Security Approaches?
  • Summary
  • Exercises
• Languages and Formal Methods
  • Why Protocol Description?
  • Why Protocol Specification?
    • Some Common Specification Systems
  • Format and Protocol Languages
  • Protocol Validation
    • State Perturbation
  • Language of Temporal Ordering Specification
    • Processes
  • Variables, Values and Expressions and LOTOS
  • Estelle
    • Overview
    • Example of a Specification
  • Communication Sequential Processes
    • Process Descriptions
    • Pictures
    • Traces
    • Traces of a Process, and Specifications
    • Specification
    • Program transformation
    • Laws of Then and Choice
    • Concurrency and Deadlock
    • Laws of Concurrency
    • Non Determinism and General Choice
    • Laws of Non Determinism
    • Concealment, Refusals, Interleaving and Divergence
    • Communication - Input, Output and Pipes
  • Introduction to the Specification Language Z
  • A Multimedia Conference Specification in Z
    • Requirements
    • Motivation
    • User Interfaces
    • Distribution
    • Floor Control
    • Off-line Components of a Conference
    • Implementation
    • Related Work
    • The User Interface
    • Readability and Usefulness
    • How to Show Who Spoke Last, and Who Will be Next
    • Starting and Continuing the Conference - Attention
    • Queues and Shows of Hands
    • Distribution of Contributions
    • Why is X Appropriate
    • The Talk model
    • Star/Mesh Duality and Rings
    • A General Floor Control Conference Model
    • Modularity of this Conferencing System
    • The FLOOR Schema
    • Useful Functions
    • Operations on the FLOOR schema
    • The ASIDE schema
    • The QUEUE Schema
    • The ALLOWED Schema
    • Promoting all the operations to act on the CONFERENCE Schema
    • More Useful Operations
    • Pictures of Floors
    • Negotiations
    • Off-line Components of a Conference
    • The Implementation
    • Conclusions
    • Conference State
  • Summary
  • Exercises
• Communications Support
  • Introduction
  • Technological Point of View
    • The Wire
    • Switching Methodologies
    • Transmission Shortcomings
    • Intermediate Devices in a Network
  • Clocks and Time in Distributed Systems
  • Communications System Modeling
  • Protocols
  • Service Types
  • Relationships between Services
  • The ISO Reference Model
    • Layering
    • Terminology and Conventions
    • The Seven Layers
    • The LAN Lower Layers
    • Historical Perspective
  • Naming, Addressing and Routing
  • Connection Oriented or Connectionless?
  • Programming Interfaces
  • OSI Application layer support for Distributed Systems.
    • Association Control
    • Remote Operations
    • Atomic Actions
    • OSI Presentation Layer Support
    • ASN.1 Principles
    • Remote Operations Service
    • Not Defined in ROS
    • Event Cycle in a ROS exchange
    • Octet-Level Encoding of ASN.1
    • Identifier Classes
    • ASN.1 Predefined Types
    • Type Definition
  • A Distributed System Example
  • OSI - a critique
  • Networked Windowing Systems
    • Portability and the X Protocol
    • Window Managers
    • Running X, a window manager and so on
    • Programming with X
    • The Libraries
  • Summary
  • Exercises
• CORBA - An Industrial Approach to Open Distributed Computing
• Modeling and Implementing Distributed Multimedia Conferencing
  • Introduction
  • Multicast Requirements for Distributed Applications
    • Conference Servers, Managers and Replication/Notification
  • Shared Networked Objects and Windows
    • Shared X
    • Shared NeWS/Display Postscript
    • Multicast
    • Audio
    • Video
    • Replicated Applications, Data and Multicast Transactions
    • Replicated Transaction Ordering: Clock Synchronisation and Timestamps
  • Classical IPC usage for Multimedia Conference Control.
    • CAR Conferencing System Components
    • Applications
    • Inter-process Communication
  • Weak RPC
  • Event Driven Approaches
  • Related Work
    • Practical Use of ANSA RPC
    • Porting to a less pure RPC
    • Source Changes - Sizes
    • RPC Types and Buffering Changes
  • The MICE Design of Conferencing Communications Channel
    • Requirements
    • Multicast Internet Conferencing
    • The MICE Project Requirements
    • Where current systems fail
    • Specific requirements
      • Modularity
      • A unified user interface
      • Flexible floor control policies
      • Scaling from tightly coupled to loosely coupled conferences
    • The Conference Control Channel (CCC)
    • CCC Names
      • address
      • type
      • instantiation
    • Reliability
    • Ordering
      • Single Source Reordering
      • Multiple Source Ordering
    • A few examples
      • Unifying user interfaces - session messages in a ``small'' conference
      • A voice controlled video conference
    • CCCP Messages
    • More complex needs
      • Dynamic type-group membership
      • Need to know
    • The Naming Service
    • Security
      • Host access security
      • Encryption
    • Conference Membership Discovery
    • CCCP Implementation
  • Summary
  • Exercises
• Application to Network Management
  • Introduction
  • Functions
    • The agents of a management system
    • Reference Configurations
    • Classification of functions
    • Non-functional requirements
  • Conceptual Architectures
    • General Model of a TMN Architecture
  • Viewpoints of the Architecture
    • The Enterprise Viewpoint
  • Aspects of Interoperability
    • The Interoperable Interface
    • Shared Conceptual Schema
    • The Information and Computational Viewpoint
  • The Single Managed Object View
    • Principles of Managed Objects
    • Attributes
    • Operations on Attributes
  • Notifications
  • Behavior
    • Generic Attributes, Actions, and Notifications
  • Specification of Managed Object Classes
  • Registration
  • The Managed Object Relationships View
  • Inheritance
    • Containment Relationships
  • Group, Service and Other Relationships
  • Relationship Definition and Representation
  • The Logical Distribution View
    • Managed Objects and Relationships to a OS
    • Authority Relationships
  • Peer-to-Peer OS Relationships
  • Abstraction
  • Management Hierarchies
  • Authority Domains
  • The Engineering Viewpoint
  • The Interoperable Interface and the OS
  • Communication Protocols
  • Management Information
  • Shared Conceptual Schema
  • Mapping the Service onto the Architecture
  • Management Protocols
  • Applying ODP and CORBA directly to Mangement
  • Distributed Systems for Managing Networks
  • Embedded Management Functionality
  • Summary
  • Exercises
• Distributed File Systems
  • Virtual File System Model
  • Consequences of Open Model
  • File (System) Naming
  • Access Protocols
  • Replication
    • Update algorithms
  • Management
  • Different Distributed Filesystems
    • The Network File System
  • The Network File System
  • AFS
  • Media File System
    • Server
    • Low Level Storage Server
    • High Level Storage Server
    • Object Constructors
    • Object Time Frame
    • Object Layout
    • DMS Client Environment
  • Security
  • Summary
  • Exercises
• Load Balancing
  • Introduction
  • ODP/ANSA Migration
  • Monitoring Distributed Systems
    • Class of information
    • Dissemination
    • Accuracy
    • Problems Inherent in Monitoring Computing Systems
    • Overview of Existing Systems and Unix Specifics
    • Solaris SunOS 5.1 Specifics
  • Migration
    • Introduction
      • What is migration?
      • Existing systems
      • Motivation
    • Policy matters
      • Language support for migration
      • Systems issues in migration
    • Communication issues
      • Message redirection
      • Message loss prevention
    • UNIX-based migration mechanisms
      • General considerations
      • The Mandelberg and Sunderam approach
    • Existing non-UNIX mechanisms
      • The V system
      • Accent/Spice
      • Emerald
    • Summary
      • Policy--mechanism separation
      • Mechanism--mechanism independence
      • Transparency
      • Preemption
      • Residual dependencies
      • Reliability
      • Efficiency
  • Scheduling
    • Introduction
      • Process Placement versus Process Migration
    • Load Distribution
    • Load Sharing
      • Condor
    • Load balancing
    • The Casavant and Kuhl Taxonomy
      • The Hierarchical Classification
      • Flat characteristics
    • Overview of a scheduler
      • Basic structure
      • Desirable properties
      • Efficiency
    • Instances of load balancing algorithms
      • The Hac and Jin approach
      • A microeconomic approach
  • Summary
  • Exercises
• Future Lessons and Challenges
  • Introduction
  • Definitions
  • Lessons and Challenges
    • Lessons Generally Accepted as True by Researchers in Distributed Systems
    • Lessons Still Highly Controversial
    • Challenges
  • Micro/Nano/Maxi Kernels - How Small is Beautiful?
  • Blocking, Synchronous and Asynchronous Interfaces - Easy?
  • Remote Procedure Call - Latent Potential?
  • Atomic Group Communication is useful?
  • Shared address spaces and Distributed Memory Models
  • Client Server Paradigm
    • Introduction
  • Unix - just another program
  • Caching at the server is good?
  • File Server Replication - How many, when?
  • Message passing - too hard for application programmers?
  • Languages, Objects and Philosophies for Distributed Systems
  • Does Maths Help?...
  • Client Caching - is it a good idea?
  • Atomicity - Useful, but too expensive?
  • Causal Ordering in multi-party communication
  • Threads and Processes -kernel and user space
  • Thread versus Process
  • Log Structured Filesystems
• References
• About this document ...