Why are you trying to avoid Inline::Java? Why do you need to call the Java programs, i.e. what do they do that can't be done in Perl? Why do you need to call Perl, i.e. why are you not just running Java services via Apache_Tomcat? Mixing techs is often a giant hassle, which is why folks coded up the Inline modules in the first place.

Probably the easiest way to interface codes the require without Inline is via the command, exchanging data via some predetermined format like JSON. You can go as simple as backticks or use IPC::Open3 or perlipc if you need more power. I'd also suggest strongly you use Taint mode if you are exposing the command line to the outside world. I would not suggest trying to tackle XS on this on your own, as it will be a total mess. Which is why someone wrote Inline::Java....