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Conclusion

Services that can provide guarantees of dependability, both qualitative and quantitative, will have a better chance of survival in the coming age of calm computing. People have always relied on guarantees in their dealings with one another. The notion of law and the development of legal systems are in many ways attempts to establish sets of expectations people can rely on: when two people sign a contract, they explicitly promise certain guarantees to each other. If they fail to keep those guarantees, the contract will be annulled, and the faulty party will not be dealt with thenceforth. The state of the Web today is similar to societies without contract law: it is immensely useful, but its arbitrariness is becoming an obstacle to the development of more sophisticated forms of use required by a vision of ubiquitously available information. In the Jini community, we should start thinking seriously about how best to facilitate such guarantees for the services we develop.

About the Author

Frank Sommers is founder and CEO of AutoSpaces.com, a startup focusing on bringing Jini technology to the automotive software market. He also serves as vice president of technology at Nowcom Corp., an outsourcing firm based in Los Angeles. He has been programming in Java since 1995, after attending the first public demonstration of the language on the Sun Microsystems campus in November of that year. His interests include parallel and distributed computing, the discovery and representation of knowledge in databases, as well as the philosophical foundations of computing. When not thinking about computers, he composes and plays piano, studies the symphonies of Gustav Mahler, or explores the writings of Aristotle and Ayn Rand. Sommers would like to thank Jungwon Jin, aka Nugu, for her tireless support and unfailing belief.

Resources

• Read Frank Sommer's complete "Survival of the Fittest Jini Services" series:
  • Part 1. Ensure the quality of Web services in the age of calm computing
  • Part 2. Use transactions to coordinate the reliable interaction of Jini services
  • Part 3. Implement transactional Jini services
• "The Coming Age of Calm Technology," Mark Weiser and John Seely Brown (Xerox PARC, October 5, 1996):
  http://www.ubiq.com/hypertext/weiser/acmfuture2endnote.htm
  
• "The Computer for the 21st Century," Mark Weiser (Scientific American, September 1991):
  http://www.ubiq.com/hypertext/weiser/SciAmDraft3.html
  
• "As We May Think," Vannevar Bush (Atlantic Monthly, July 1945):
  http://www.theatlantic.com/unbound/flashbks/computer/bushf.htm
  
• "How Much Information Is There in the World?" Michael Lesk:
  http://www.lesk.com/mlesk/ksg97/ksg.html
  
• Homepage of Gerhard Weikum, available papers:
  http://www-dbs.cs.uni-sb.de/~weikum/home.htm
  
• Jim Gray's homepage:
  http://www.research.microsoft.com/~gray
  
• For more information on John von Neumann's relevant work, see his article "Probabilistic Logic and the Synthesis of Reliable Organisation from Unreliable Parts." Collected Works, Vol. 5, A.H. Taub, Editor (Pergamon Press, 1961-1963). The article also appears in Automata Studies: Annals of Mathematics Studies, C.E. Shannon and J. McCarthy, Editors (Princeton University Press, 1956). He describes this issue also in "Principles of Large-Scale Computing Machines," Collected Works, Vol. 5, reprinted also in Annals of the History of Computing, Vol. 3, (Princeton University Press, July 1981). For a fascinating account of his work on the brain, see The Computer and the Brain, John von Neumann, et al. (Yale University Press, November 2000):
  http://www.amazon.com/exec/obidos/ASIN/0300084730/javaworld
  
• "The Semantic Web," Tim Berners-Lee, James Hendler, Ora Lassila (Scientific American, 2001):
  http://www.scientificamerican.com/2001/0501issue/0501berners-lee.html
  
• "The Rio Architecture Overview, Version 1.0" (Sun Microsystems):
  http://www.sun.com/jini/whitepapers/rio_architecture_overview.pdf
  
• HP Laboratories' e-services projects have studied the notions of "exactly once" guarantees from e-services, as well as service composability:
  http://www.hpl.hp.com/org/stl/emd/
  
• "Data Processing Spheres of Control," (IBM Systems Journal, 1978; vol. 17, issue 2; pp. 179-98). For a list of online articles from IBM Systems Journal, visit:
  http://www.ibm.com/Search?v=10&lang=en&cc=us&q=IBM+Systems+Journal
  
• The Ninja project at Berkeley aims to define a highly robust infrastructure for Web services, using Java. At the core of Ninja is a cluster, which provides high availability and scalability for services:
  http://ninja.cs.berkeley.edu/
  
• The Infospheres projects at CalTech explores the notion of objects representing services on the Web, and the idea of composable services:
  http://www.infospheres.caltech.edu/
  
• David Gelernter's "The Second Coming -- A Manifesto," (The Third Culture):
  http://www.edge.org/3rd_culture/gelernter/gelernter_index.html
  
• "What Is Mean Time Between Failure (MTBF)?" (Western Digital):
  http://www.wdc.com/products/drives/drivers-ed/mtbf.html
  MTBF FAQ:
  • http://www.t-cubed.com/faq_mtbf.htm
  • http://www.hardwaregroup.com/faq/gen_mtbf.htm
• D.H. Brown's availability research:
  http://www.dhbrown.com/cffiles/RPPage.cfm?ID=202
  
• IEEE Distributed Systems Online on dependable systems:
  http://www.computer.org/dsonline/dependable/
  
• For more information about streams-based computing and ScopeWare, visit the Mirror Worlds Website:
  http://www.scopeware.com
  
• Jini FAQ and resources at Artima.com, maintained by Bill Venners:
  http://www.artima.com
  
• "Proving the Correctness of Multiprocess Programs," Leslie Lamport (IEEE Transactions on Software Engineering, Volume 3, Issue 2, 1977) -- only the abstract is available online:
  http://research.compaq.com/SRC/personal/lamport/pubs/pubs.html#proving
  
• Read past Jiniology columns:
  http://www.javaworld.com/javaworld/topicalindex/jw-ti-jiniology.html
  
• The most comprehensive book on transactions processing (and, in general, on making distributed systems reliable) is Transaction Processing: Concepts and Techniques, Jim Gray and Andreas Reuter (Morgan Kaufmann, 1993):
  http://www.mkp.com/books_catalog/catalog.asp?ISBN=1-55860-190-2
  
• Recent research into transactions has produced large and impressive literature. A good collection of essays on the subject is Database Transaction Models for Advanced Applications, Ahmed K. Elmagarmid (Morgan Kaufmann, 1992):
  http://www.mkp.com/books_catalog/catalog.asp?ISBN=1-55860-214-3
  
• A collection of papers on transaction logic is available from Anthony Bonner's Website:
  http://www.cs.toronto.edu/~bonner/papers.html#transaction-logic
  
• Sign up for the JavaWorld This Week free weekly email newsletter and keep up with what's new at JavaWorld:
  http://www.idg.net/jw-subscribe
  
• Chat about all things Java in ITworld.com's Java Forum:
  http://www.itworld.com/jump/jw-0413-jini/forums.itworld.com/webx?14@@.ee6b2b4
  

"Survival of the Fittest Jini Services, Part I" by Frank Sommers was originally published by JavaWorld (www.javaworld.com), copyright IDG, April 2001. Reprinted with permission.
http://www.javaworld.com/javaworld/jw-04-2001/jw-0413-jiniology.html

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