This is the same syncronization problem you have with using servlet
httpsession objects. As you stated in your initial query, the only safe way
I know of is to synchronize on a common object.
eg:
synchronized(myHttpSession){
myStatefulBean.changeMyData(newData);
}
I really don't recommend using EJBs from JSPs. There are too many possible
exceptions that can occur. I recommend that you do any EJB interaction in
servlets and only after you are finished processing anything that is likely
to throw an exception, then pass data via local beans to your JSP page for
display purposes.
eg: // in a servlet:
synchronized(myHttpSession){
myLocalBean = myStatefulBean.getMyStateData();
}
req.setAttribute(myLocalBean);
this.getServletContext().getRequestDispatcher("displaypage.jsp").forward(req
,res);
John Zerbe - Mellon Bank
Information Technology Solutions - Middleware Team
Phone: 412-234-1048 E-Mail:[EMAIL PROTECTED]
> -----Original Message-----
> From: Graham Parsons [SMTP:[EMAIL PROTECTED]]
> Sent: Thursday, May 11, 2000 11:21 AM
> To: [EMAIL PROTECTED]
> Subject: Re: Queuing requests to a Session Bean
>
> Chris,
>
> I don't see how a pool would help our case. We are effectively trying to
> either stop the client issuing two requests or ensure that they are both
> processed.
>
> All requests are aimed at the same STATEFUL session bean. How would a
> pool of stateless help us (even if they subsequently got a reference to
> the stateful bean, they still have to somehow queue the messages - I
> assume that a EJB-EJB call within the container is treated as the same as
> a client-EJB call across the container boundary as far as single method
> invocation at any one time is concerned).
>
> Cheers
>
> Graham
>
> -----Original Message-----
> From: A mailing list for Enterprise JavaBeans development
> [mailto:[EMAIL PROTECTED]]On Behalf Of Chris Raber
> Sent: Thursday, May 11, 2000 3:38 PM
> To: [EMAIL PROTECTED]
> Subject: Re: Queuing requests to a Session Bean
>
>
> Create a pool of stateless session bean references in your client. An
> example pooling mechanism is in the Developer's Guide that you can get
> from
> our web site. It it open source...
>
> Regards,
>
> -Chris.
>
> > -----Original Message-----
> > From: Graham Parsons [SMTP:[EMAIL PROTECTED]]
> > Sent: Thursday, May 11, 2000 7:12 AM
> > To: [EMAIL PROTECTED]
> > Subject: Queuing requests to a Session Bean
> >
> > Are there any suggested design patterns for queuing multiple requests to
> > the same Stateful Session Bean (in order to avoid the exception because
> > Session Beans can only handle one request at a time).
> >
> > We are in an HTML - JSP - Java - EJB environment and the user is
> clicking
> > more than one button at a time - both of which send a request to the
> same
> > session bean.
> >
> > We could use:
> >
> > * JavaScript to disable the buttons once one is clicked
> > * Trap multiple clicks in the JSP or Java layer and queue (synchronise I
> > presume on a common method)
> >
> > Neither is very attractive as we are being code intrusive and I just
> > wondered how others had got around this problem.
> >
> > Thanks
> >
> > Graham
> >
> >
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