<?php
class News_ControllerPublic_Index extends XenForo_ControllerPublic_Abstract
{
    public function actionIndex()
    {
        $newsId = $this->_input->filterSingle('news_id', XenForo_Input::UINT);

        if ($newsId)
        {
            // User is viewing a single article so fetch and display it
        }
        else
        {
            // User wants to view all news articles so fetch them all and display them
        }
    }
}
?>