JavaSpaces in Practice

"Phil Bishop and Nigel Warren have been pioneers in the use of JavaSpaces™ to build realsystems that solve real problems. This book is an excellent distillation of their accumulatedwisdom on this subject, and will save any programmer using the technology far more time than itwill take to read. It is also well written and clearly presented, a rarity in technical booksthese days. I learned a lot reading it."

— Jim Waldo, Distinguished Engineer at Sun Microsystems, lead architect for the Jininetworking technology and JavaSpaces.

This book will show you how to use JavaSpaces to build practical, scalable distributed systems.It will increase your understanding of where JavaSpaces are applicable, and how to use themeffectively within your system architecture.

JavaSpaces™ in Practice is structured in three parts:

• Part One focuses on patterns for designing and evolving entries from the basics to advanced distributed data structures.
• Part Two covers designs and idioms associated with remote events, code mobility, and both transient and persistent spaces.
• Part Three highlights some practical applications including implementing smart proxies, location-based services and agent systems, together with guidelines and tips for testing and tuning JavaSpaces.

Developers and programmers with some experience in Java will learn by example a set of idiomsthat make distributed systems more dynamic and flexible.

I. ENTRIES.

2. Designing Entries.
Background.
An Initial Entry.
Entry Wrapping.
Interfaces for Entries.
Factories for Entries.
Design Alternative.
Entries for Existing Frameworks.
The Payload Idiom.
3. Evolving Entries.
Maintaining Compatibility.
Standard Techniques and Data Loss.
Using Inheritance to Add Fields.
Removing Fields from Entries.
Evolving Nested Key Fields.
An Alternative to Nested Key Fields.
Problems with Entry Evolution.
4. Simple Distributed Data Structures.
Simple Data Structures.
Ordered Data Structures.
Iterating.
5. Hierarchical Distributed Data Structures.
Organizational Structures.
Complex Matching.
Generic Distributed Trees.

II. MECHANICS.

6. Codebases.
Basic Requirements.
The Codebase System Property.
7. Remote Event-based Idioms.
IntroducingRemote Events.
The Handback Event Handler.
Object Interactions.
Adding Event Handlers at Runtime.
Leases.
Event Registration.
Sequence Numbers.
Transactions.
Leases And Transactions.
Using An Event Mailbox.
Reliability.
8. Code Mobility Behaviour-based Idioms.
Introducing Code Mobility.
What Goes on Behind the Scenes?
Introducing Behavior-based Idioms.
Building an Employee System.
Using Subclassing to Modify Behavior at Runtime.
Using Classloaders to Modify Behavior at Runtime.
Security and Mobile Code.
9. Using Transient and Persistent Spaces.
Transient Spaces.
Persistent Spaces.
Accessing Different Spaces.
Specifying Storage Models with Entries.
Mixing Snapshots.
Registering the Mixed Proxy.

III. APPLICATION.

10. Process Coordination.
Request-Response Model.
Implementing the Model.
Coordinating Multiple Services.
11. Location-based Services.
Location-Based Systems.
Packit Shifters - Case Study.
Finding Locatables in a Space.
12. Bidding and Agent Systems.
A Time Bidding System.
Typesafe Constants with Spaces.
Agents and Spaces.
The Customer Agent.
The Driver Agents.
Letter Counter Service.
13. Testing Space-based Systems.
A Space Logging System.
A Local Logging Proxy.
Reviewing the Design.
The JavaSpace Logging Service.
Alternative Designs 2.
14. Tuning Space-based Systems.
A Lightweight Counter.
Tuning Local Code.
Using Snapshot.
Imitating Snapshot.
General Entry Optimizations.
Date Matching.
Time and Spaces.
Server Tuning.
Conclusion.
Appendices.
A: Code Listings.
B: Tips and Rules in This Book.
References.
Index.