I have a need to integrate a third-party Java applet into a custom web part I wrote for SharePoint 2007. The web part simply loads a user control I created that contains the bulk of the functionality, and that's where the applet will go. I added it to my user control project and it works fine outside of my SharePoint environment.
I installed the updated web part onto my MOSS 2007 development site and the part's page loads fine. The applet is triggered by clicking a link button on the page, which runs some client-side JavaScript to start it. The problem is nothing seems to happen when I click the link. No error messages appear, and the stuff the applet is supposed to do never occurs (it's for doing file transfers via FTP). I have the .jar file as an embedded resource in my user control DLL, which is deployed to the bin folder, and SharePoint fully trusts this DLL.
I used Firebug to step through the initialization code and I saw an HTTP GET that failed with a message about not being authorized, but it didn't give any details and I'm not positive it was related to the applet.
Is there anything special I need to do to make the applet work? Or am I going about this the wrong way?
EDIT: The problem turned out to be the .jar file for the applet couldn't be found. SharePoint is clearly doing something different here, and I need to find out what. Can Java applets be used within a SharePoint site? This question suggests they can, but in that case a Page Viewer web part was used, which isn't going to really work for me.