I've got an internal only app that I've historically self-signed. With the latest version of Java, self-signing for JNLP is deprecated. I have also experienced strange problems with opening sockets from self-signed apps with Java 7U25 (but work fine when run as a normal jar from the command line).
Is there a way to do JNLP without signing at all? Given that it's an internal only app, signing is not necessary (to me). I really don't want to spend money buying a certificate when it's not truly necessary.
Yes, possible (but not recommended).
If you are using it only internally (locally) you could lower your java security settings from high to middle then you are able to execute your app again. But then I would probably deactivate your web browser plugin...