RE: ServletSession's and Servlet Reloading

[Scott Lawrence]

Title: RE: ServletSession's and Servlet Reloading

Also, I want to emphasize that the solution mentioned is not desirable.  Maintaining session information even after reloads promotes rapid development.  It allows one to build up a session and then work on a single servlet, compiling again and again, without rebuilding the session or using a 'shortcut' servlet to build the session after every reload.  Several weeks ago, someone on this list raised the same issue and they resorted to using their own session implementation.  I think this is largely unecessary since the Serlvet Container is capable of dealing with this using the standard spec.

 

In any case, how do others deal with this situation?  I have been rebuilding the session using a separate servlet after each recompile of the servlet being tested.  It's tedious and prone to human error and often makes me wish that I had purchased VAJ and Websphere as twisted as that may sound.

 

[Scott Lawrence] 

 -----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Hani Suleiman
Sent: Tuesday, August 08, 2000 10:03 AM
To: Orion-Interest
Subject: RE: ServletSession's and Servlet Reloading

This behaviour actually makes a lot of sense when you consider how classloaders work in java. It is impossible to throw away any given class, in order to do ANY reloading of anything at all, you need to throw away the classloader, and make a new one and load classes through it. Now, another factor to throw into the mix is that in order for two classes to be equal, they must have the same class, AND be loaded through the same classloader. Hence, when you've reloaded classes, all classes in your session are now invalid. There is no way around this, I'm afraid! The solution is to ensure that things are initialised properly in your servlet startup code. Eg, where you first create the session, make sure you invalidate the existing one.

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Scott Lawrence
Sent: Monday, August 07, 2000 11:12 PM
To: Orion-Interest
Subject: ServletSession's and Servlet Reloading

Orion 1.1.37 (as well as all other versions as far as I remember) lose the
Servlet Session whenever a servlet is reloaded.

Why is this?  Is this an issue with how classloaders are used?  This makes
working with complex sessions very difficult to test and debug since each
time I recompile a servlet, I'll lose the session when that servlet is
reloaded.  Other servers do not destroy the session (Websphere for instance)
when reloading servlets.  Have I missed something or is there a setting that
prevents this from happening?