code: @Override
      public boolean permit(ReqContext context, String operation, Map params) {
          if ("execute".equals(operation)) {
              return permitClientRequest(context, operation, params);
          } else if ("failRequest".equals(operation) || "fetchRequest".equals(operation) || "result".equals(operation)) {
              return permitInvocationRequest(context, operation, params);
          }
          // Deny unsupported operations.
          LOG.warn("Denying unsupported operation \"" + operation + "\" from " + context.remoteAddress());
          return false;
      }
docs: Authorizes request from to the DRPC server.
  
  @param context the client request context
  @param operation the operation requested by the DRPC server
  @param params a Map with any key-value entries of use to the authorization implementation