http://jsp.java.sun.com/javaone/javaone2000/event.jsp?eventId=988&ts=9669744
73136
Dave Wolf
Internet Applications Division
Sybase
> -----Original Message-----
> From: A mailing list for Enterprise JavaBeans development
> [mailto:[EMAIL PROTECTED]]On Behalf Of Bhattacharyya, Ana
> Sent: Tuesday, August 22, 2000 10:20 AM
> To: [EMAIL PROTECTED]
> Subject: Re: Failure over handling
>
>
> 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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> >
>
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