PersistenceService denies permission when running an Applet

Question

I'm converting an application that uses JWS to run inside a browser. Ok, so it's not just a matter of changing <application-desc> to <applet-desc> (which is just about the only change I made to the jnlp), but the problem I'm getting is not one I expected.
try {
      URL newURL = new URL(newURLBase);
      InputStream is = ps.get(newURL).getInputStream();
      userProps.load(is);
      is.close();
    } catch (FileNotFoundException fne) {
      // nothing to do
    } catch (Exception e) {
      // any other error is bad
      Globals.nonFatalMsg(null, classId, propsFailureMsg, newURLBase, e.getClass().getName(), e.getMessage());
    }This code is throwing a MalformedURLException. (ps is an instance of PersistenceService). The Message returned by getMessage() is that access to persistent data was denied for the URL.
This exact code works perfectly well when run from the desktop application. I'm serving the same jar for the application and the applet. So the URL in newURL is exactly the same for both the application and the applet (I'm serving them both from the same IIS web site). Just the HTML and the JNLP are different.
I thought JWS applets and applications run in exactly the same sandbox. And I thought PersistenceService didn't need any kind of permissions. (Although the JavaDoc does say this can happen.)
Could this be a Browser issue? I get the same result in FireFox and IE. Could it be a java.policy issue?
I'm running 1.6.0_20.

Answer 1

Doctor_Dad wrote:
I converted Andrew Thompson's JotPad application, which illustrates the use of the Persistence Service in a JWS Application, to run as an Applet and got exactly the same result.
From which I can only conclude that the Persistence Service doesn't work with Applets.
Has anyone out there ever used the Persistence Service with Applets? Short story, no. I had your post flagged from when I first saw it, thinking "When I get time.." - but had not found any time yet.
I'll check the Bug Parade to see if this has been reported...Good idea. It is not quite clear how a variety of the services of the JNLP API should translate to embedded applets. These would namely be.
- SingleInstanceService // not an applet's right to control browser instances
- BasicService.showDocument(URL) // replaces the applet page or opens new browser/tab?
- IntegrationService // 1.6.0_18+ - shortcuts and menu items are not appropriate for an embedded applet.
I was about to include the PersistenceService in that list, but ultimately it makes every bit of sense to allow embedded JNLP applets to have access to serialisation between runs. The older methods of applets storing data are now probably blocked to the JNLP embedded applets (e.g. creating a cookie).
If you cannot find anything in the bug DB, please raise a bug report and request the documentation address all these areas.
Edit 1:
By 'bug report' above, read 'request for enhancement'. Whether it is a bug depends on Sun's expectation of what they wanted the API to do. ;)
Edited by: AndrewThompson64 on Jun 15, 2010 10:06 AM
Edit 2:
BTW - did you try it with a free-floating applet as well, or just an embedded applet?
Edited by: AndrewThompson64 on Jun 15, 2010 10:47 AM