JSON RPC and Ruby/Rails

Does anyone have some experience using some JSON-RPC service wit Ruby
and Rails ?

To illustrate it, I need to POST this data:
{
“method” : “service.get”,
“id” : “me”,
“params” : {
“userId” : “me”,
“groupId” : “self”
}
}

To this server:
Server URL: http://www.service.com/service/rpc

Thanks in advance.