RE: Beginner java question: Serializable

As long as that particular session is active you are
correct that you do not need to serialize anything
because you have your data stored as objects in the
session scope. But what happens if the user walks away
for lunch and his session times out? You would hope
that the last state of the user's session was somehow
saved in order to start him back up where he left off.
The two commonly used methods to do this are to either
store the data in a database, or to serialize the data
just prior to the session being invalidated. Then when
the user logs back on, your app can restore the data
from one of those.

Obviously, you're not going to serialize every
instance of a serializable class... only when you need
to. But in order to do so, you have to declare your
class as implementing the Serializable interface, or
as a sublass of something else that does so.

FYI - As mentioned previously, serializable has been
used for remote processing across separate JVMs, and
is  also used on occasion to clone objects. Cloning
objects in java can be a bit cumbersome sometimes,
especially with user defined objects. Serializable
allows for a quick & easy save/restore mechanism.

One word of caution though... serialized objects are a
potential security hole for hackers. Once the data is
serialized, it can be tampered with. So be careful
where you place it. 

Thanks,
Ivan Hurtado
 
--- Lim Hock-Chai <Lim.Hock-Chai@xxxxxxxxxxxxxxx>
wrote:

> Using shopping cart as an example.  I would think
> when I save the ordered Items to a session, I will
> save it as a Collection of those Item objects, which
> does not require Serialize (I don't think anyway).  
> 
> Can you give example?
> 
> -----Original Message-----
> From: java400-l-bounces@xxxxxxxxxxxx
> [mailto:java400-l-bounces@xxxxxxxxxxxx]On Behalf Of
> Ivan Hurtado
> Sent: Monday, December 20, 2004 9:45 AM
> To: Java Programming on and around the iSeries /
> AS400
> Subject: Re: Beginner java question: Serializable
> 
> 
> Common uses are...
> 
> 1) To save session data in order to be able to allow
> users to pick up where they left off. They may have
> been in the middle of some activity when they logged
> off (or if their session timed out) and the app can
> then use the serialized info to restore right back
> to
> where they were.
> 
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