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Hello,

I am looking for a solution to ensure that only one client instance of an application is startet.

The termination must happen before Dispatcher instantiation.

Is that something that should be managed within the starting process (javaws)?

Regards,
Joachim

...you have to make sure by your server side appliaction which refuses to open up a second (meaningful) session.

Please note: put a SESSIONCLOSER into the outest page (BEANPROCESSING > SESIONCLOSER) so that the session is closed if the one (allowed) instance is closing. On dispatcher side the destroy of the dispatcher is called.

Regards, Björn

Hi Björn,

...you have to make sure by your server side appliaction which refuses to open up a second (meaningful) session.

That's a very late. Any servlet listener or filter means that the client has been loaded. What should happen then?

Do You (or anybody) have some clues what can be managed inside Java Webstart?

Regards,
Joachim

Joachim,

compare the client with the browser. You cannot prevent the user from starting the browser! But the server side application has to rule things like "only one logon allowed".

Of course you could write an own Swing program calling the client internally, and this Swing program may do whatever is possible... ;-)

Regards, Björn

Hi Joachim,

I had the same requirement for my project.
One possible (my) solution:
- create something like this:
class JnlpDownloadServlet extends jnlp.sample.servlet.JnlpDownloadServlet
Example how the default works, you'll find in the Java Servlet JNLP example.

- First servlet request creates a session ID (Cookie_ID) and extend this to the JNLP query String.
- Create customiezed JNLP template like this:
<jnlp spec="1.0" codebase="$$codebase" href="$$name?$$querystring">
...
<argument>faces/yourapp/outer.jsp?$$querystring</argument>

- registered Dispatcher when created:
// register client context for link into an existing session
JnlpDownloadServlet.registerJnlpListener(this);

- Second call (to JNLP servlet) check the Cookie_ID and decide:
a) answer a JNLP call page (or)
b) send request to existing instance and answer a HTML page (mybe with force startup)

- Last point: Add WindowFocusListener (UIComponent) to your existing application. This check, if some startup parameter has to handle, when focus the current application window.

This works fine for me and only a single application is started.
Limitations:
- Only webstart oriented
- Empty browser window is left open. Close with java script will need user interaction (security dialog)

If you have any questions, just let me know...

regard,
Roland