Doing synchronous JSON on rails

Rails
1

So I have found how to generate json in a rails app in the wiki
(Peak Obsession), what I have
yet to figure out is how to make a synchronous call via json to rails so
that I can block while fetching the information from a user request.

context:
I have used JSON on top of java in the past, and in order to make
synchronous calls I had to do the following:

  1. include json.js

  2. add the json object to the page:

    <jsp:useBean id=“JSONRPCBridge” scope="session
    class=“com.metaparadigm.jsonrpc.JSONRPCBridge” />

  3. in the jsp, register a json object as an object that can be called
    from the javascript of the page

    <% JSONRPCBridge.registerObject(“myTestObject”, aTestObject); %>

  4. Register the JSON Servlet

  5. Then call the function either async:

    jsonrpc.myTestObject.myFunction(myCallBack, “hello”);

or sync:

    var result = jsonrpc.myTestObject.myFunction("hello");
    alert(result);

I would like to know how I would go about getting to #5 in rails and
Peak Obsession really only
explains the actual writing out of the JSON object.

Thanks,
Devon Jones