Jason Casey

Stefan,

The message "sealing violation: can't seal package ... already loaded" should occur when loading a class that extends another 'sealed' class. I.e. extends a class that cannot be extended (according to this article). However, I imagine this exception may also occur in some special situations where multiple versions of the same class are being loaded. There are some goog articles on the web for diagnosing ClassLoader issues such as this.

Depends what you want to use it for: To reduce code size or make it hard for people to read your decompiled code.

If you're looking to reduce the size of your jar/ear/war files, I think obfuscators are good. I used to use an open source one (sorry forget which, but google and look for a mature one).

If you're looking to keep people from reading your code, they can be ok - generally people aren't bothered to decompile and understand your code, unless they want it badly. I would suggest almost any obfuscator will keep nosey people from looking at or reusing your code, and no obfuscator will stop someone who is dead serious.

So just use a free, mature, open source one is my advice. Don't waste time and money finding anything else.

I would suggest the following may be causing this kind of error:

1. (obvious) IP address is incorrect - try PING <ip>
2. The port is not open, or is blocked by a firewall - try TELNET <ip> <port>
3. The DB listener is not running or is binding to a different network interface - again, TELNET should confirm this (also use Oracle client tools to connect)
4. No local ports are available for the out-going connection (unlikely) - only if you're making thousands of connections, or creating hundreds of new connections every minute.

These are first things I would check, then I'd start looking at the application code (checking drivers, confirming the code is doing what I expect). If you're still stuck after that, you can take a look at how this exception is being thrown - see http://www.insideexceptions.com/en/jdk-1-5-0/java-sql-SQLException.html and search the page for "ioexception". From you there you can probably trace the problem into the IOException (http://www.insideexceptions.com/en/jdk-1-5-0/java-io-IOException.html) which is where the real problem seems to be. But if you get to that stage you probably need to be fairly experienced with Java, etc. Usually this kind of error is one of the obvious things listed above.

If you still have problems, I suggest posting the entire exception message here.

the username & password in these files is encryped using AES, and if you don't have a key, getting the values would be hard

It should still be possible to retrieve the password for the WebLogic Admin Console using the method described here.