so technically you can access any java library you want from your arc code as long as it's in your classpath. Ultimately though it's prettier to hide these calls behind macros or functions in arc so your code is more expressive. I've done this a little for swing (java's desktop UI library) - for example there are event handler macros like
As for serving on a shared host - I switched from java to ruby a while ago precisely because it's a pain to use java on a shared host - and most java hosting plans offer a shared tomcat (tomcat: popular java app server) instance, so even then you couldn't use arc's webserver natively. You could implement the necessary servlet interfaces in arc and then package it like a java web app and tomcat would deploy it. So at least the logic of your app would be written in arc. If you want to try this, I'll be happy to help.
Nice to know that java isn't too hard to access, not that I expected it to be.
As for hosting, I'm currently using dreamhost. They provide support for python and perl via fastcgi, so I've been looking for a lisp option that could leverage that. Most of them don't have much in the way of libraries. And I like arc. So the option of using arc with java libs seems like a plus. How hard do you think it would be to write arc's web tools based off of fcgi? Unfortunately I don't even know what it takes to run rainbow via the jvm on a server, but I would presume that it's possible.