Dealing with session timeout and container managed security

[marcelstoer]

Is there some consensus or best practice in the GWT community as for
how to deal with session timeout and container managed security? There
are some pointers if you search for this subject, but some of the
ideas are wild...

In my case I use the Servlet container's built in security features
for authentication as described in the Servlet specification. Hence,
in my web.xm I protect access to the GWT application like so:

<security-constraint>
<web-resource-collection>
<web-resource-name>my app</web-resource-name>
<url-pattern>/app/*</url-pattern>
<http-method>GET</http-method>
<http-method>POST</http-method>
<http-method>PUT</http-method>
<http-method>DELETE</http-method>
</web-resource-collection>
<auth-constraint>
<role-name>*</role-name>
</auth-constraint>
</security-constraint>

<login-config>
<auth-method>FORM</auth-method>
<form-login-config>
<form-login-page>/public/login.jsp</form-login-page>
<form-error-page>/public/login.jsp?retry=true</form-error-page>
</form-login-config>
</login-config>

<security-role>
<role-name>*</role-name>
</security-role>

So, the application (host/bootstrap page, RPC Servlet, etc.) is in the
"app" folder and the login form (login.jsp) is in the "public" folder.
This works flawlessly except for the session timeout use case.
The application sends an RPC request to /app/AppServlet, the Servlet
container requires authentication because the session had timed out
and dutifully *forwards* to the login page. Hence, the result of the
request is not some RPC/JSON/XML object as expected by the client but
the login page HTML structure. The client simply isn't prepared for
that and freezes i.e. doesn't do anything.

I believe that on the server side everything is set up correctly. If
the session timed out the requests don't even reach the RPC Servlet
because it's intercepted by the container, fine.

But how do you deal with this in the client?
Should one write some custom AsyncCallback class that handles the
reponse sent by the container?

Thanks for your feedback.
Marcel

[marcelstoer]

Hhhmm, the community being quiet can mean a lot of things...none are
really positive.

Was I talking about some dark GWT corners where no stable/proper
solutions exist?
Or is there simply "no right way" to solve my problem, but rather many
potential solutions that all have their flaws?

[Jason Essington]

The problem with jumping ahead of the RemoteServiceServlet for your
authentication is that you don't have a good way to communicate to GWT
that there was an authentication exception.

I tend to do my JAAS login inside the RemoteServiceServlet where I can
throw a checked AuthenticationException which I can in turn handle
gracefully on the client side.

consider this scenario:

User loads a rather large cash worksheet that he needs to fill, the
user begins filling the worksheet, then takes a break, and returns to
complete the worksheet. This user then submits the completed worksheet.

Now, with the previously mentioned technique, the session is checked
before the request is deserialized and the server notices that the
session has expired, and throws an authentication exception. The
client recieves that exception in the onFailure() method of the
callback and takes appropriate action to have the user reauthenticate.
once that process is successful, the client application can resubmit
the original request, and the user has not lost any of his work.

If you use the default form based the world just stops, the user is
forced to reauthenticate outside the scope of the application, and his
progress is lost. This really aggravates customers by the way.

-jason

[marcelstoer]

Thanks for your feedback. I can see where your approach comes from
given the mentioned scenario.

However, I neither do want to check for proper i.e. still valid
authentication in all of my RemoteServiceServlet methods nor would I
want my GWT application tie to an authentication mechanism at all. I'd
like one and the same GWT app to work in a secure environment and in a
"regular" environment - without changing the code. Those were my
reasons to go with the container-managed-security-approach.

[Rakesh]

we use server push for session time out and it works really great!

[marcelstoer]

What do you mean by "server push"? Could you maybe elaborate on your
approach a little, thanks.

[Adligo]

Hi All,

I use a timer in the gwt app to ping the server so that the session
doesn't expire. If the user loggs out or closes the browser window
the timer stops pinging the server and the session times out. This
has its flaws for sure!
For instance the user logged in at a public computer and forgets to
close the browser window or log out.
But at least I don't need to catch failures in every rpc/ajax call
to try to figure out if the session expired.
I suppose people could call this 'server push' but I generally have
issues with the terms 'push and pull' in computer architecture.

More comments are in this class;
http://cvs.adligo.org/viewvc/gwt_util/src/org/adligo/gwt/util/client/BaseController.java?view=markup

Cheers,
Scott

[hazy1]

I handle this in the following way:

Use a servlet filter to check the status of the authentication. Check
the URL requested (this can be done using a specific kind of filter
mapping and initialization parameter), if it is a GWT request then
send back an encoded exception that the GWT client will understand.
If it is a request for a 'normal' html/jsp/etc then forward to an
error page.