final int sign = request.getSignature();
switch (sign) {
case QueryRequest.SIGNATURE:
final String query = ((QueryRequest) request).getQuery();
BackendProcessor proc = _sched.dispatchRequest(request);
result = proc.execute(query, this, returnType);
_sched.notifyCompletion(request);
break;
default:
throw new IllegalStateException("Illegal return type: " + returnType);
}