code: function invoke(dataset_id, params, callback) {
    debug('invoke');
  
    if (arguments.length < 3) throw new Error('invoke requires 3 arguments');
  
    // Verify that fn param has been passed
    if (!params || !params.fn) {
      var err = new Error('no fn parameter provided in params "' + util.inspect(params) + '"');
      debugError('[%s] warn %s %j', dataset_id, err, params);
      return callback(err, null);
    }
  
    var fn = params.fn;
  
    // Verify that fn param is valid
    if (invokeFunctions.indexOf(fn) < 0) {
      return callback(new Error('invalid fn parameter provided in params "' + fn + '"'), null);
    }
  
    // We can only continue if sync has connected to its dependencies i.e. mongo & redis
    if (!syncConnected) {
      return callback(new Error('Sync not connected'));
    }
  
    var fnHandler =  module.exports[fn] || server[fn] || server.api[fn];
  
    server.api.start(function() {
      return fnHandler(dataset_id, params, callback);
    });
  }
docs: Invoke the Sync Server.