Chao bon anh nhe
----- Original Message -----
From: T.A. Flores <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, April 05, 2001 8:18 PM
Subject: Re: Record-locking in J2EE/JSP/Servlet apps?
> Have you posted this to the EJB list?
>
> I know this was discussed on EJB quite a while ago, I just don't
> remember the outcome. However, you might want to move the question
> there and see what those list members have to say on the mattter -
>
> ----- Original Message -----
> From: Keith Kwiatek <[EMAIL PROTECTED]>
> Date: Thursday, April 5, 2001 8:37 am
> Subject: Re: Record-locking in J2EE/JSP/Servlet apps?
>
> > I think you mean "any time you want to work pessimistically" ....
> >
> > This is an outstanding issue.... I have also been wrestling with
> > the same
> > thing for a while now.... and it seems, for now, that the kludgy
> > timestampmethod is about the only solution.... I saw some more
> > discussion on this
> > issue on www.theserverside.com about this very issue, but I
> > forget exactly
> > where on the web site....
> >
> > EJB doesn't address "pessimistic" row level locking in a stateless
> > environment --BUT IT SHOULD! EJB must address this issue at some
> > point... it
> > is such a basic requirment! The whole idea of the J2EE is to
> > provide a
> > framework of basic utilities shared by applications.
> >
> > Keith
> >
> > ----- Original Message -----
> > From: "Jonathan Goldberg" <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Wednesday, April 04, 2001 11:07 PM
> > Subject: Re: Record-locking in J2EE/JSP/Servlet apps?
> >
> >
> > > Hi Bill
> > >
> > > I don't know that this problem is specific to JSP, and
> > > I don't know if EJB solves the problem automatically.
> > >
> > > Basically, any time you want to work optimistically, you
> > > will need to verify that the data you are trying to update
> > > is the data you retrieved. One manual strategy is to add
> > > a timestamp to the table(s), and do something like:
> > >
> > > {
> > > retrieve data without transaction
> > > display data to user
> > > }
> > >
> > > later on
> > > {
> > > get data sent by user
> > > open transaction
> > > retrieve data from database
> > > compare timestamps
> > > if same then
> > > {
> > > update data with user database
> > > update timestamps
> > > commit transaction
> > > send OK confirmation to user
> > > }
> > > else
> > > {
> > > rollback transaction
> > > send new data and error message to user
> > > }
> > > }
> > >
> > > Hope this helps
> > >
> > > Jonathan
> > >
> > > ==========================================
> > > Jonathan Goldberg 8, HaP'nina Street
> > > Amdocs (Israel) Ra'anana, 43000, Israel
> > > +972-9-7762071 (work) +972-9-7763800 (fax)
> > > mailto:[EMAIL PROTECTED]
> > >
> > >
> > > -----Original Message-----
> > > From: Hines, Bill [mailto:[EMAIL PROTECTED]]
> > > Sent: Wednesday, April 04, 2001 9:44 PM
> > > To: [EMAIL PROTECTED]
> > > Subject: Record-locking in J2EE/JSP/Servlet apps?
> > >
> > >
> > > How are any of you solving the problem in the stateless webapp
> > contextwhere
> > > two users pull up the same record from a database in a JSP page,
> > and user
> > > one changes the address and saves but then user two, who has the old
> > address
> > > on his JSP page, changes the phone number and hence over-writes
> > user one's
> > > address change? Are you locking the record in the back-end
> > database and
> > then
> > > implementing the SessionBindingListener to release it when the
> > session> expires, if the user leaves the webapp without logging
> > out? Does EJB solve
> > > this problem? I'd like to hear the solutions that are out there.
> > >
> > >
> >
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> > >
> > >
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> >
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> >
>
>
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> Some relevant FAQs on JSP/Servlets can be found at:
>
> http://java.sun.com/products/jsp/faq.html
> http://www.esperanto.org.nz/jsp/jspfaq.html
> http://www.jguru.com/jguru/faq/faqpage.jsp?name=JSP
> http://www.jguru.com/jguru/faq/faqpage.jsp?name=Servlets
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Some relevant FAQs on JSP/Servlets can be found at:
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http://www.jguru.com/jguru/faq/faqpage.jsp?name=JSP
http://www.jguru.com/jguru/faq/faqpage.jsp?name=Servlets
