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From "Jerry Jalenak" <Jerry.Jale...@LABONE.com>
Subject RE: Please help clarify or confirm -- HttpSession
Date Thu, 13 Jun 2002 18:54:14 GMT
Free?  Didn't realize that......

-----Original Message-----
From: Jerome Jacobsen [mailto:jerome.jacobsen@gentootech.com]
Sent: Thursday, June 13, 2002 1:50 PM
To: Struts Users Mailing List
Subject: RE: Please help clarify or confirm -- HttpSession


Huh?  JBoss is FREE.

-----Original Message-----
From: Jerry Jalenak [mailto:Jerry.Jalenak@LABONE.com]
Sent: Thursday, June 13, 2002 2:41 PM
To: 'Struts Users Mailing List'
Subject: RE: Please help clarify or confirm -- HttpSession


Kevin,

I actually thought about the EJB solution, but we are trying to do this on
the cheap without having to buy an EJB container (i.e. JBOSS).  Something I
was wondering about though - is it possible to run an EAR structure under
Tomcat?  I'm not very familiar with EJB, so forgive me if I sound stupid
here, but is it possible to create a pseudo-J2EE environment and create an
Entity-Bean that can do this?

The XML-Soap solution also is appealing, but we would like to be able to
integrate these various app's with a minimum of re-write.

Jerry

-----Original Message-----
From: Kevin.Bedell@sunlife.com [mailto:Kevin.Bedell@sunlife.com]
Sent: Thursday, June 13, 2002 1:18 PM
To: Struts Users Mailing List
Subject: RE: Please help clarify or confirm -- HttpSession



The container makes sure that Session ID's are unique. It sets the cookie
as well - nothing in the webapp has to do this. This is just how the
containers work.

Regarding storing "objects from webapp A in a shared classloader class
keyed by the sessionID and retrieve them from
webapp B".

First, you can't physically store an object in another webapp because the
memory spaces are isolated from each other. Second, having common
directories on the two CLASSPATHS for the two webapps allows you to load
CLASSES to create new objects, but not to share the objects once they are
created.

But there are ways to share objects (in addition to classes) between
webapps. And at times there may be good reasons to do so.

For example, imagine you have an object representing a transaction to be
executed on your system (maybe a stock trade). What if:

 - The user who entered the transaction wants to see its real-time status.
 - A trader who is going to execute the transaction needs to see it, and
 - An auditor needs to monitor all trades currently in the system.

Imagine also you want them to use three seperate webapps (or non-servlet
applications) to do their work. While not the only approach, it is possible
to have all access the same physical Java object. Here are some ways:

1. Implement the Object as an Entity EJB in an EJB container such as JBOSS.
Have all the webapps (or whatever) connect to the same EJB Container
instance and manipulate the data in the object. The EJB container will
manage locking and transactional integrity for you as well.

2. Create the object as a singleton in some JVM somewhere and wrap an RMI
server around it. This is basically a hack, but I saw it done once to allow
clustered applications to share Properties objects between them (ensuring
they were all using the same Properties). (And, yes - it was a pain.)

3. Put the object behind a web service and access it via SOAP. This allows
some of the clients to be non-Java.

All these solutions are based on putting the object in some place OUTSIDE
any of the individual webapps.



















"Joseph Barefoot" <josephb@hereuare.com> on 06/13/2002 02:09:43 PM

Please respond to "Struts Users Mailing List"
      <struts-user@jakarta.apache.org>

To:   "Struts Users Mailing List" <struts-user@jakarta.apache.org>
cc:    (bcc: Kevin Bedell/Systems/USHO/SunLife)
Subject:  RE: Please help clarify or confirm -- HttpSession


hmmm...but the sessionIDs have to be unique, even across web apps.,
correct?
If there weren't unique, URL rewriting would not work correctly if two
users
using two webapps on the same app. server happened to get the same session
ID.  Therefore, one *should* be able to store objects from webapp A in a
shared classloader class keyed by the sessionID and retrieve them from
webapp B.

Am I missing something here? (besides why the hell you would want to do
this)
:)


joe

> -----Original Message-----
> From: Kevin.Bedell@sunlife.com [mailto:Kevin.Bedell@sunlife.com]
> Sent: Thursday, June 13, 2002 10:46 AM
> To: Struts Users Mailing List
> Subject: RE: Please help clarify or confirm -- HttpSession
>
>
>
> In general, there is no way session info from one webapp can be made
> visible to other webapps. Some details of this may vary depending on your
> app server.
>
> Sessions are controlled by cookies being set on the client. The "cookies"
> that are set by each webapp are scoped for that webapp only. As
> an example,
> create the following .jsp file and name it session.jsp. Put it in
> "webapp1"
>
> <html>
>   <head>
>     <title>Testing Session Management</title>
>   </head>
>   <body>
>     <% out.print("Session ID = " + request.getSession().getId() );  %>
>   </body>
> </html>
>
>
>
> Then, if you were to do a low-level http request from the server,
> you'd see
> something like:
>
>
> bash-2.05$ ./telnet -E localhost 8080              [ <-- I type ]
> Trying 127.0.0.1...
> Connected to localhost.
> Escape character is 'off'.
>
> GET /webapp1/session.jsp HTTP/1.0                   [ <-- I type ]
>
> HTTP/1.1 200 OK
> Content-Type: text/html;charset=ISO-8859-1
> Date: Wed, 12 Jun 2002 00:39:49 GMT
> Server: Apache Tomcat/4.0.3 (HTTP/1.1 Connector)
> Connection: close
> Set-Cookie: JSESSIONID=AC75B22FD1D283D1CEF0136928110679;Path=/webapp1
>
> <html>
>   <head>
>     <title>Testing Session Management</title>
>   </head>
>   <body>
>     Session ID = AC75B22FD1D283D1CEF0136928110679
>   </body>
> </html>
>
> Connection closed by foreign host.
> bash-2.05$
>
>
> The JSESSIONID cookie is used by the servlet container to manage the user
> session.
>
>
> Notice that the the scope of the JSESSIONID Cookie in this example is
> limited to the '/webapp1' web application. So even if you have many web
> applications (or Struts applications) deployed in a servlet container,
> session tracking is isolated between them.
>
>
>
> <ShamelessPlug>
> I'll be covering topics such as this and others in my upcoming book
> "Struts: Rapid Working Knowledge" to be published by SAMS later this
year.
> </ShamelessPlug>
>
>
> HTH,
>
> Kevin
>
>
>
>
>
> "Jerry Jalenak" <Jerry.Jalenak@LABONE.com> on 06/13/2002 01:43:50 PM
>
> Please respond to "Struts Users Mailing List"
>       <struts-user@jakarta.apache.org>
>
> To:   "'Struts Users Mailing List'" <struts-user@jakarta.apache.org>
> cc:    (bcc: Kevin Bedell/Systems/USHO/SunLife)
> Subject:  RE: Please help clarify or confirm -- HttpSession
>
>
> This is something I've wondered about, especially in a team development
> environment where there are several programmers working on different
> webapps
> that need to share a common framework - in other words, something like
> this:
>
>  Tomcat\webapps
>   framework-application
>    WEB-INF
>    ...
>   webapplication_1
>    WEB-INF
>    ...
>   webapplication_2
>    WEB-INF
>    ...
>   etc etc etc
>
> Can the classes in webapplication_1 'see' session data that was
> created and
> stored in the session by the framework-application?
>
> Jerry
>
> -----Original Message-----
> From: emmanuel.boudrant [mailto:b7st@yahoo.fr]
> Sent: Thursday, June 13, 2002 12:39 PM
> To: Struts Users Mailing List
> Subject: Re: Please help clarify or confirm -- HttpSession
>
>
>
> At my knowledge, under tomcat each webapp have his own
> "memory space" so you can't share HttpSession between
> 2 webapp. You can share object between 2 webapp with
> one condition, the class to be shared must be loaded
> in same ClassLoader.
>
>
> Did you understand my english ;)
>
> -Emmanuel
>
>
>
>  --- "Yuan, Tony" <Tony.Yuan@cingular.com> a écrit : >
> Hi Guys,
> > Can anyone help clarify or confirm the relationship
> > between an HttpSession
> > and a web application? I mean, can two WAR (two
> > application) share one
> > common HttpSession and whatever resource this
> > HttpSession contains?
> >
> > My understanding is that if WARs are deployed
> > separately, then there will be
> > different HttpSessions and therefore you can not
> > share resources among them.
> > Can anyone help confirm this? or correct if I am
> > wrong?
> >
> > Thanks!
> >
> >
> > --
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