Jruby or Ruby(1.9.1) with Rails for lots of Java Backends


I'm working on a project that requires a lot of web triggered java
applications. For instance, when a user click a search button, I call
java from Rails to do the heavy weight. Is it troublesome to call java
application from ruby(on rails)? Can Jruby simplify calling java
application and, further more, will it give more flexibility with my
java backend applications?

Also, I wonder that Jruby with Rails is stable and fast. In fact, Ruby
1.9.1 is much faster than the previous version and more stable(?, I
guess compare to Jruby). What would you recommend in this situation?

Thanks guys!