Problem Using JApplet that Accesses a Database on a Web Application Using Netbeans 6.5.1

Question

I created a JApplet using Netbeans 6.5.1 that accesses a database. When the program is run by itself, it runs perfectly. The issue is when you try to put it online using a web application in Netbeans, it will not access the database. I was told by somebody that the problem is that Java security will not allow you to do this. Is this correct? How do I fix this problem? Thanks.

Answer 1

As already mentioned, an unsigned applet can only make network connection to the host from which the applet originated. However, if the database is hosted on a different server than the originating applet then you will have to make the applet signed. If the application is not for production use, you can self sign the applet (not suitable in production use where the signing has to be done by a trusted Certificate Authority. Certificate authorities typically charge a fee for the service of validating their clients' credentials.) However, for testing and demo purposes, you can create a self-signed certificate. With self-signed certificates, the browser displays a warning to the user mentioning that the information given in a self-signed certificate has not been validated by a trusted third party (Certificate Authority).

For self signing the applet take a look at the following links:

http://java.sun.com/developer/onlineTraining/Programming/JDCBook/signed.html

http://www-personal.umich.edu/~lsiden/tutorials/signed-applet/signed-applet.html

The other things to keep in mind are the JDBC driver types to use. Type-1 and Type-2 drivers are not suitable to be used within applet due their dependence on native binary code. Type-3 and Type-4 are ones you should be using to connect to database from within an applet.

The best solution is to NOT make database connection from an applet (if possible) but instead use a server side application to connect to the database on behalf of the applet.

Answer 2

as Clint pointed out, an applet is only allowed to connect to it's origin server. to work around this, you can sign your applet with a certificate from a root authority, but certificates cost 200-400$/year.