Session Limitation with Acegi

Sometimes it's useful to restrict a user a single session.  This
simplifies the logic needed to guarantee certain restrictions.

For example, I always want a user to have a minimum of one valid email
address.  With two parallel sessions and two valid emails a user could
delete one email in each session and I would need to verify consistency in
the database.  Restrictig to one session lets me implement the restriction
in the business logic.

However, the exact configuration was not obvious.  After some
experimentation the following seemed to work.

First, you need some way of detectig when sessions expire.  This is
largely automatic as long as you register the following in web.xml:

  <!-- used to track session events (single user session) -->
  <listener>
    <listener-class>org.acegisecurity.ui.\
      session.HttpSessionEventPublisher</listener-class>
  </listener>

I have all my authentication-related xml in web-authentication.xml (and
referenced via context-param in web.xml).  It includes:

  <bean id="authenticationManager"
    class="org.acegisecurity.providers.ProviderManager">
    <property name="sessionController" ref="singleSession"/>
    <property name="providers">
      ...
    </property>
  </bean>

  <bean id="sessionRegistry"
    class="org.acegisecurity.concurrent.SessionRegistryImpl"/>

  <bean id="singleSession"
    class="org.acegisecurity.concurrent.ConcurrentSessionControllerImpl">
    <property name="maximumSessions" value="1"/>
    <property name="exceptionIfMaximumExceeded" value="true"/>
    <property name="sessionRegistry" ref="sessionRegistry"/>
  </bean>

Which is all that is needed (I suspect sessionRegistry is supplied by
default anyway).

The way it seems to work is as follows:
- authenticationManager calls the appropriate provider
- if that succeeds, it calls sessionController
- sessionController applies the appropriate logic, using the information
  in sessionRegistry
- sessionRegistry is correct because of the event system (which includes
  the listener you registered).

Andrew

Session Limitation with Acegi blog post

---------------------------- Original Message ----------------------------
From:    "m zyzy" <myzyzy@...>
Date:    Thu, October 9, 2008 10:40 pm
--------------------------------------------------------------------------

First of all, I am new in spring and acegi , and I know the post is a bit
old, but I am stuck with acegi v1.0.4 - Spring security V2.0.4 -wait for
me-We'll meet in my next project..

why you dont use this filter below ? is there an explanation as why you
didnt use it?
<bean id="concurrentSessionFilter"
class="org.acegisecurity.concurrent.ConcurrentSessionFilter">
      <property name="sessionRegistry"> <ref bean="sessionRegistry"/>
</property>
      <property name="expiredUrl" value="/login.jsp"/>
    </bean>

I also use the same config xml code as you wrote in the blog post but with
the addition of above code and it's work fine for me (of course, with the
above code , I need to add the concurrentSessionFilter in the
filterChainProxy's filter sequence).

-Second as we both use the way that to prevent second login attempt at a
time in different machine/browser , how to show a text message in a jsp
page to indicate that the unsuccessful second logger of user he/she is
trying to log in to is in used already currently? How this can be done?

Thanks .

No Idea!

Hi,

No idea why I didn't use that - perhaps it wasn't around when I wrote the
code?  Perhaps I missed it?

Curiously, it's not mentioned at
http://www.acegisecurity.org/guide/springsecurity.html#concurrent-sessions
either.

I haven't used Acegi since this post, so I'm afraid I can't help more (but
thanks for posting - people do sometimes read this page, according to my
logs, so it will help them).

Cheers,
Andrew

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