I have 1 more question regarding this matter.
During the upgrade of the servlet, I need to
1. serialize the current session using that servlet
2. undeploy the old servlet
3. deploy the new servlet
4. deserialize the session saved in #1
During this window (from step 1 to 4), if there is a request coming in for
those sessions (either during serializion or deserialization), what will
happens?
Will that request drop?
Or that request will be queued by Tomcat, and it will be served when the
whole upgrade is done?
-----Original Message-----
From: Shapira, Yoav [mailto:[EMAIL PROTECTED]
Sent: Monday, March 08, 2004 11:20 AM
To: Tomcat Users List
Subject: RE: Hotswap servlet code in Tomcat 5?
Hi,
Is Counter Serializable?
Yoav Shapira
Millennium ChemInformatics
>-----Original Message-----
>From: Samuel Cheung [mailto:[EMAIL PROTECTED]
>Sent: Monday, March 08, 2004 12:15 PM
>To: 'Tomcat Users List'
>Subject: RE: Hotswap servlet code in Tomcat 5?
>
>Thanks.
>
>I try this, but it is different from what I expected.
>
>In my doGet() of my servlet, I have a Counter object in my session.
>When I reload the page in my browser, I see the value of the counter
>increments. (say from "0" to "1" to "2").
>
>Then I go to the Tomcat manager web page, and then "undeploy" the
original
>servlet, and "deploy" a newer version of the same servlet (context name
is
>the same). The value of the counter starts from "0" again when I reload
the
>page again.
>
>The difference between the orginal servlet and the new servlet is the
name
>of the Method "inc()". I rename it to "newInc()" in the new servlet.
>
>I am expecting the value of the counter will be "3" when I reload the
>browser after I undeploy/deploy the servlet. Is this a correct
assumption?
>
>Here is the portion of the doGet() method in my servlet.
>
> public void doGet(HttpServletRequest request,
> HttpServletResponse response)
> throws IOException, ServletException
> {
> HttpSession session = request.getSession(true);
>
> Counter sessionCounter = (Counter)
>session.getAttribute("session_counter");
>
> if (sessionCounter == null) {
> sessionCounter = new Counter();
> session.setAttribute("session_counter", sessionCounter);
> }
>
> // rename inc() to newInc()
> sessionCounter.inc();
> out.println("session counter =");
> out.println(sessionCounter.getValue());
> }
>
>
>-----Original Message-----
>From: Shapira, Yoav [mailto:[EMAIL PROTECTED]
>Sent: Friday, March 05, 2004 7:44 AM
>To: Tomcat Users List
>Subject: RE: Hotswap servlet code in Tomcat 5?
>
>
>Hi,
>
>>If the objects in the session is serialized to the disk and then
>>re-serialized when I re-deploy my servlet, what happens if the class
in
>my
>>newer version of my servlet has
>>- added/removed methods/attributes in the class
>>- added/removed static variables in the class
>>
>>How will the hotswap work?
>
>One has nothing to with the other, unless you're design is so bad that
>it places a instance of your servlet class as a session attribute.
>
>Yoav Shapira
>
>
>
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