Erl4j provides a framework for creating Java daemons that can respond to Erlang RPC messages. 

Dependencies:
 * Java 1.6
 * jsvc 1.0.1 (http://commons.apache.org/daemon/jsvc.html)
 * Jinterface 1.5.1 (part of Erlang/OTP)
 * Rake 0.8.7
 
Erl4j may work with other versions of those dependencies, but those are just the ones I've tested it in.

Before running Erl4j, make sure that epmd is running, otherwise it won't be able to publish its port to other Erlang nodes. To start epmd:
  /usr/local/lib/erlang/erts-$SOME_VERSION/bin/epmd -daemon
  
To start a server with the samples, run:
  rake run

To test it out, start an Erlang process with:
  erl -sname my_node

For some reason, it won't work without the sname param.

Then from the interpreter you can run:
  rpc:call('erl4j@my_host', my_module, my_function, [param1, param2]).

And it should echo the call back to you:
  {call,my_module,my_function,[param1, param2],<0.31.0>}

To create your own Erl4j server, you just have to implement the Erl4jHandler interface which is simply:

  public interface Erl4jHandler {
      public OtpErlangObject respond(Erl4jRequest request);
  }

Then update bin/erl4jctl.conf to use your Erl4jHandler implementation class. 

OtpErlangObject is Jinterface's Java representation of an Erlang term. See http://www.erlang.org/doc/apps/jinterface/jinterface_users_guide.html.

See erl4j-sample/com/syntacticbayleaves/erl4j/sample/ for examples.