The Results persistence layer is called ResultsService.php but is fairly tricky to work with because it requires an instance of taoResultServer_models_classes_ReadableResultStorage to be passed to it as an implementation.

Step 1: Create a constants.php file and add it to your module

You need to create a constants.php file and make sure it is placed in the following location \includes\constants.php

Add the following includes to your constants.php file

Step 2: Import the correct classes into your module

Add the following class imports at the top of your module

Step 3: Add class variables to your module

Add the following class variables to your module

protected $resultsService;
protected $rdsResultsStorage;

Step 4: Modify your construct() to initialize all the variables

Add the following code to your construct() function in your module, while this code creates a new RdsResultsStorage which really should be called as a singleton, it keeps the code simpler rather than extending the GenerisPersistence layer which may cause a lot of confusion.

public function __construct() {
    //Set variables to access the persistence layer
    $this->rdsResultsStorage = new RdsResultStorage();
    $this->resultsService = ResultsService::singleton();