Hi Dave,
I was brainstorming over this problem -- "the same work occurs twice". Can u
give me the URL of ur presentation. I am very intersted in knowing the
solution.
TIA
Anamitra
-----Original Message-----
From: Dave Wolf [mailto:[EMAIL PROTECTED]]
Sent: Monday, August 21, 2000 9:33 PM
To: [EMAIL PROTECTED]
Subject: Re: Failure over handling
They simply start the whole transaction over again. The downed app server
would have caused a downed database connection which would have caused the
database to rollback the tx.
The real risk however is that the work COMMITED before the app server went
down, resulting in the same work occuring twice. For instance
1) container begins tx
2) bean votes to commit
3) container commits
4) hardware fails while container trying to marshall return status to client
5) client detects this as a failure, and replays method on server2
Blammo, the same work occurs twice. This can be managed via the use of a
'handshake' design pattern. Basically aquire the PK value to the table
first and use it to create the new entity. Place code to detect the
duplicate primary key exception, and simply consume it. For more info see
my presentation at JavaOne (TS988) on "Double Dipping".
Dave Wolf
Internet Applications Division
Sybase
> -----Original Message-----
> From: A mailing list for Enterprise JavaBeans development
> [mailto:[EMAIL PROTECTED]]On Behalf Of Larry Liu
> Sent: Monday, August 21, 2000 6:22 PM
> To: [EMAIL PROTECTED]
> Subject: Failure over handling
>
>
> Hi:
>
> I have a EJB classic issue need to be handle:
>
> In the web based production environment, how to handle application server
> failure over?
> Using multiple Application servers, or multiple instances of application
> server, such as
> weblogic application server cluster. But if one app server down, or one
> instance down,
> how other app server or app server instance clear know the current
> transaction status
> of the failure server instead of restart the whole transaction again? If
> this is not
> the good solution, do you have any other technical options?
>
>
> Thanks
> Larry
>
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