code: function onProcCall(method, path /* devid , propname*/, args) {
      switch (method) {
      case 'GET':
          return onProcCallGet(method, path /* devid , propname*/, args);
      /* case 'POST' :
          if(devid!='settings' || args == undefined)
              return {error:'The format is wrong for settings.'};
          if( args.schedule instanceof Array && logger.updateschedule(args.schedule) )
              return {success:true,message:'New schedule settings are successfully saved'};
          else
              return {error:'Error in saving scheduled logging'};*/
      }
      const msg = `The specified method ${method}`
            + ' is not implemented in admin plugin.';
      return {error: msg};
  }
docs: onCall handler of plugin
  @param {string} method Caller method, accept GET only.
  @param {string} path Plugin URL path
  @param {object} args parameters of this call
  @return {object} Returns a Promise object or object containing the result