Hi Nishant,
where did you read that <distributable> will *enforce* serializability?
AFAIK <distributable> "only" means that your sessions can be distributed
to different tomcat nodes (i.e. a cluster). It doesn't enforce anything,
you have to make sure that your session attributes are serializable by
yourself.
I've done this for my testing environment with a SessionListener:
public class SessionListener implements HttpSessionListener,
HttpSessionAttributeListener {
private ObjectOutputStream stream = new ObjectOutputStream(new
OutputStream() {
public void write(int b) {}
});
public void attributeAdded(HttpSessionBindingEvent evt) {
if (LOCAL_DEBUG) {
// try to serialize attribute
Object o = evt.getValue();
synchronized (stream) {
try {
stream.writeObject(o);
} catch (IOException e) {
System.err.println(evt.getName() + " is not serializable: " +
e.getMessage());
e.printStackTrace();
}
}
}
}
...
}
I disable LOCAL_DEBUG in the production environment, because trying to
serialize every attribute is probably to expensive under heavy load.
@Lintang:
That wouldn't help any. If you put your attributes (which are not
serializable) into a HashMap (which CAN (!) be serializable) the
resulting object (map + attribute) still wouldn't be serializable.
Serializable is more than just implementing the java.io.Serializable
interface.
greetings,
Christoph
Lintang JP wrote:
hi Nishant,
You might want to put all your session variable inside HashMap or other
datatypes that implements Serializable, rather than put it just in a single
variable. Refer to the javadocs, what are those Serializable data types are.
Or maybe you can build your own class with something like this :
public class StoredSessionValue implements Serializable {
// your session variable goes here
// your setter and getter method for those variables goes here
}
You did right on your <distributable/> tags.
On 8/17/05, Nishant Deshpande <[EMAIL PROTECTED]> wrote:
Hoping for some help from the tomcat experts on this list.
I want to ensure all objects stored in sessions are serializable.
I read that I can put the <distributable/> tag in my web.xml file to
'enforce' this.
But I don't see any enforcing happening. I assumed it would throw
exceptions at runtime when I did 'setAttribute("xxx",
SomeNonSerializableObject)'.
I have put 'distributable' in
web.xml: <web-app> ... <distributable/> ... </web-app>
I also have the following in server.xml:
<DefaultContext reloadable="true" allowLinking="true">
<Loader className="org.apache.catalina.loader.DevLoader"
reloadable="true" debug="1"/>
<Manager className="org.apache.catalina.session.PersistentManager"
pathname="/cv/data/tmp" debug="5" saveOnRestart="true"
distributable="true">
<Store className="org.apache.catalina.session.FileStore"
directory="/cv/data/tmp"
debug="5"/>
</Manager>
</DefaultContext>
Am I missing something? How is the serializability enforced?
Also another question: the serialization does not happen in the
directory i specify for Store above, rather it happens in the
$CATALINA_HOME/work/Catalina/* directories. Any ideas about this one?
Thanks,
Nishant
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