At 10:15 AM 1/31/00 +0100, you wrote:
> Paolo De Lutiis wrote:
> >
> > Hi,
> >
> > I'm trying to balance my web application among different JServ but I
> > found the following problem:
> > when one JVM crushes (caused by SW/HW failure) my clients loose their
> > sessions.
> > I'd like to know if there are standard methods to overcome this problem,
> > for example keeping
> > the httpsession objects in a rmi server heap, or dbms ( or like).
> > Any ideas ? Any examples ?
> >
> > Thanx
> >
> No way. You'll have to code it, not difficult IMO, but "application
> dependant" : what do you save ? what about transactions ? etc ...
>
> Jean-Luc
I put together something like this. Here's how it went:
* Add stuff to JServServletManager to manage a config parameter for a
"save-session-path".
* In JServServletManager.init() create and start a thread that will
periodically save "dirty" sessions to disk.
* In removeSession(), make sure you delete the saved file, if it exists.
* Modify JServSession to add variables to track the save-path (if any), and
a "dirty" flag that tracks un-saved changes.
* In JServSession.putValue() and removeValue(), set dirty=true.
* Also in JServSession, add some methods to write the session object to a
specified file. You can do this via writeObject() to an
ObjectOutputStream. The filename is constructed using a directory path and
the session ID.
* In JServConnection.getSession(), add code to the effect that if a
session ID was specified by the client, but the session is not in-memory,
look for it on disk and if found, create a new session object and re-load
it from the file. Delete the file after you finish.
* If you stash any beans/etc as session values, make sure they implement
Serializable.
That's the summary. Stashing to file is easy to do, but you could use a DB
if you really wanted to. With either approach, you need a resource (either
shared file path or DB server) that has high assurance of always being
available.
- Fernando
=======================================
Fernando Salazar <[EMAIL PROTECTED]>
w -781-392-2514
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