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About JXTA's support for transaction processing  RSS feed

 
Shuai Liu
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Hi,
Can you tell me something about JXTA's applicability in distributed database and transaction processing areas, or where I can find relevant info?
I came to this forum just two weeks ago and found out this is such a good place!
Thank you for looking.
 
Michael Ernest
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I have two words for applying P2P computing to transaction processing: big mistake. Transaction services are widely regarded as the prototype that drives the thin client/fat server model.
The things that transaction processors typically rely on -- two-phase commit support, client connection handling, persistence, archive/redo logging, SQL parsing, and so on -- all contribute to a heavyweight construct on the backend: a big honkin' database, application server(s) to tie the relationship between database and clients, and finally the clients themselves, all chugging away at data load and store requests.
It's not a good fit for P2P. Even distributed ultimately rely on some highly-available root service to drive the whole schmeer. Coming and going as you please is not an option in those models, which is what P2P enables.
 
Shuai Liu
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Thank you for your explanation.
Do you mean it's not suitable to deploy a distributed computing architecture based on P2P to carry out transaction processing?
Why there's need for DTP then? I am confused.
 
Michael Ernest
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Hi Shuai -
Aha. Distributed transaction processing; I thought you were headed in that direction but I though I'd wait until you brought it up.
So for starters, yes, I am saying JXTA is unsuitable for DTP either. Here's my rationale:
There are two essential roles for modelling transactions: managers and participants. The manager is responsible for coordinating the ready and commit states of the participants; the particpants, modelled as state machines, are required to post their current state in discrete stages. The manager coordinates the call to have everyone commit, or to have everyone 'roll back' if something goes wrong.
The criteria of this two-phase commit model are described as an ACID test: the model must demonstrate Atomicity of execution, Consistency of operation, Isolation of activity, and Durability of process. In short, correct (and usually timely) transaction processing implies reliable participants and certainly highly-available managers.
Peers operate in a far looser context; it's just not a good fit.
 
shailesh sonavadekar
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for distributed transaction , you will require distributed sytems or say distributed o.s. does jxta is fulfilling that role ?
 
Michael Ernest
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Distributed transactions don't have to occur on multiple OS's at all. A distributed transaction is simply one in which multiple data repositories are coordinated to support a single action. Those databases could all exist on one machine if you wished.
Of course it's more likely that the databases we're coordinating each live on different systems. And you could argue of course that a database could be a Peer. The assertion is an academic one. Peers are typically seen as relatively lightweight and 'unreliable' systems (they'll go away whenever they feel like it).
Even Scott McNealy seems P2P as anathema to transaction systems. Here are his comments on JXTA as a part of computing's future.
 
Sing Li
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Michael,
You're amazing. The ranch is very fortunate to have you. I hope you'll make it over to jxta.org someday.
While I would never say transactions are "NEVER" applicable to pure P2P systems, what you say is pretty darn accurate with respect to the 'current thinking' amongst both the academics and bleeding edge architects.
Jini does use 'loose' transactions to perform 2PC based distributed synchronization (non ACID)... but that's definitely not traditional "transactions", but rather a novel use of the mechanism that enables distributed transactions.
Essentially, the question has no "correct" answer, and is up to some innovators to prove us all wrong.
.. boiler plate follows...
Thank you, everyone, for a fascinating discussion this week and posting excellent questions. Congrats to the lucky winners.
Anybody who is interested in JXTA should definitely check out the open source site where everything is happening. http://www.jxta.org/ It is where I hang out. There are many commercial companies that are profiled there, complete with links to their websites and description of their products and services.
Of course, my book should also help you to get a quick start on it .
Best Regards,
Sing Li
 
Shuai Liu
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Michael,
Thank you so much for your information. I didn't expect an answer in such details.
Have a nice weekend.
 
Fei Ng
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"You're amazing. The ranch is very fortunate to have you. I hope you'll make it over to jxta.org someday"

agree! lolz !! he is amazing! I am totally new to this and now i am very interested in learning it cuz of his post!
and thanks Sing Li for the great book!
[ February 15, 2002: Message edited by: FEI NG ]
 
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"Michael, You're amazing. The ranch is very fortunate to have you."
And Sing Li becomes the most cited author on the Ranch
I cited these words in "Moderators Only" a minute ago.
 
Doug Wang
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"Michael, You're amazing. The ranch is very fortunate to have you."
Thanks Michael and Sing Li, we are lucky to have you this week.
 
Mapraputa Is
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Ok, by now "Michael, You're amazing. The ranch is very fortunate to have you." was cited four times. Oops, sorry, already five.
 
With a little knowledge, a cast iron skillet is non-stick and lasts a lifetime.
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