Strange Session Behavior....

[James Morgenstein <jm...@recommend-it.com>]

All-

I am having some problems with retrieving my beans out of sessions on JSP
pages.

Some background, I'm using Tomcat 3.2b8 (also tried 3.1) with Apache 1.3.x
on Linux with Sun's JDK1.3.  Under Tomcat 3.2b8, I have disabled cookies and
am using URL rewriting exclusively.

My problem is this.  I have declared the constructor on my Beans as private
(contrary to the Bean pattern, but necessary for subclassing), because at
the start of all operations within my system, I use a factory to construct
the beans based on input parms.  Once I construct the beans, I insert them
into the session using:
   BeanClass instance = BeanClass.getInstance( subclass data );
   session.putValue( "beanName", instance );
In my subsequent JSP pages I am using a useBean syntax with session scope to
retrieve the beans for processing such as:
   <jsp:useBean id="beanName" scope="session"
class="com.recommendit.beans.BeanSubClass"  > </jsp:useBean>

This is working properly for most of my pages and most of my users; however,
I am occasionally getting errors on pages indicating that the bean cannot be
created by the useBean syntax.  This to me says that the bean is not in the
session.

Possible thoughts on the cause of this problem:
1)  I am setting the bean in the session incorrectly (however, it works fine
for the vast majority of my users)
2)  Can the session be getting destroyed by some other outside influence?
3)  ????

Thanks for the help.

James

Re: Strange Session Behavior....

["Craig R. McClanahan" <Cr...@eng.sun.com>]

James Morgenstein wrote:

> All-
>
> I am having some problems with retrieving my beans out of sessions on JSP
> pages.
>
> Some background, I'm using Tomcat 3.2b8 (also tried 3.1) with Apache 1.3.x
> on Linux with Sun's JDK1.3.  Under Tomcat 3.2b8, I have disabled cookies and
> am using URL rewriting exclusively.
>
> My problem is this.  I have declared the constructor on my Beans as private
> (contrary to the Bean pattern, but necessary for subclassing), because at
> the start of all operations within my system, I use a factory to construct
> the beans based on input parms.  Once I construct the beans, I insert them
> into the session using:
>    BeanClass instance = BeanClass.getInstance( subclass data );
>    session.putValue( "beanName", instance );
> In my subsequent JSP pages I am using a useBean syntax with session scope to
> retrieve the beans for processing such as:
>    <jsp:useBean id="beanName" scope="session"
> class="com.recommendit.beans.BeanSubClass"  > </jsp:useBean>
>
> This is working properly for most of my pages and most of my users; however,
> I am occasionally getting errors on pages indicating that the bean cannot be
> created by the useBean syntax.  This to me says that the bean is not in the
> session.
>
> Possible thoughts on the cause of this problem:
> 1)  I am setting the bean in the session incorrectly (however, it works fine
> for the vast majority of my users)
> 2)  Can the session be getting destroyed by some other outside influence?
> 3)  ????
>

Sessions get destroyed only when they time out or when you invalidate them.

However, I'd bet the cause of your problem is a forgotten call to
response.encodeURL().  This will cause the next request in to start a new
session -- and if that request goes directly to a JSP page (so your bean
construction hasn't yet had a chance to execute) you will get the results you
see.

On the other hand, I don't see why you need a private constructor to allow
subclassing.  I subclass things that have public constructors all over the place
(in both Tomcat and Struts) without problems, and I can't think of any benefits
to doing what you are doing.

>
> Thanks for the help.
>
> James

Craig