Add simple library for accessing Oracle DB via PDO

configs/dbaccess.cnf

+username = "<username>"
+password = "<password>"
+pdo_dsn	 = "oci:dbname=//<hostname>:<port>/<servicename>"
\ No newline at end of file

examples/dbaccesstest.php

+<?php
+use jards\eventsapi\DBAccessService;
+
+/*Copyright (c) 2017, Forschungszentrum Juelich GmbH, Federal Republic of Germany.
+ All rights reserved.
+
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.*/
+
+require_once __DIR__.'/../vendor/autoload.php';
+
+$dbaccess = DBAccessService::getInstance(__DIR__.'/../configs/dbaccess_jsc.cnf');
+$data = $dbaccess->sql_select('select * from rev_groups');
+
+var_dump($data);
+
+?>
\ No newline at end of file

lib/DBAccessService.php

+<?php
+/*Copyright (c) 2017, Forschungszentrum Juelich GmbH, Federal Republic of Germany.
+ All rights reserved.
+
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.*/
+
+namespace jards\eventsapi;
+
+/**
+ * Simple library for access Oracle DB 
+ *
+ */
+class DBAccessService{
+	
+	/**
+	 * DB username
+	 * @var string
+	 */
+	private $dbuser;
+	
+	/**
+	 * Connection object for PDO access
+	 * @var unknown
+	 */
+	private $conn;
+	
+	/**
+	 * Mapping of file path for DB credentials to instance of DBAccessService
+	 * @var array
+	 */
+	private static $instances;
+	
+	/**
+	 * Returns an instance of DBAccessService or null on failure.
+	 * Creates a new instance if no one is present or no connection was established.
+	 * @param string $DB_Pass_file optional filepath for DB credentials
+	 * @return DBAccessService instance of this class
+	 */
+	public static function getInstance($DB_Pass_file=NULL){
+	
+		if(empty($DB_Pass_file)){
+			$DB_Pass_file = __DIR__.'/../configs/dbaccess.cnf';
+		}
+		
+		if( empty(self::$instances) || ! array_key_exists($DB_Pass_file, self::$instances)
+				|| self::$instances[$DB_Pass_file]  == null || empty(self::$instances[$DB_Pass_file]->conn)
+				|| self::$instances[$DB_Pass_file]->conn == false ){
+					self::$instances[$DB_Pass_file] = new DBAccessService($DB_Pass_file);
+					if( empty(self::$instances[$DB_Pass_file]->conn)
+							|| self::$instances[$DB_Pass_file]->conn == false ){
+								return null;
+					}
+		}
+		return self::$instances[$DB_Pass_file];
+	}
+	
+	/**
+	 * Creates a new instance of DBAccessService. Attempts to establish a DB connection.
+	 * @param string $DB_Pass_file filepath for DB credentials
+	 * 
+	 * @throws \PDOException if connection via PDO did not work
+	 */
+	protected function __construct($DB_Pass_file){
+		$config = parse_ini_file($DB_Pass_file);
+		
+		$this->dbuser = $config['username'];
+		$dbuser = $config['username'];
+		$pass = $config['password'];
+		$options = array();
+		$pdoDSN = $config['pdo_dsn'];
+	
+		// pdo
+		$this->conn = new \PDO($pdoDSN, $dbuser, $pass, $options);
+	}
+	
+	/**
+	 * Run SQL select statement and get the result as an array of rows.
+	 * 
+	 * @param string $sqlStatement the SQL statement to run
+	 * @param array $input_parameters bound parameters in the sqlStatement
+	 * 
+	 * @throws Exception if statement could not be executed
+	 */
+	public function sql_select($sqlStatement, $input_parameters = null){
+		$sth = $this->conn->prepare($sqlStatement);
+		if(!$sth->execute($input_parameters)){
+			throw new \Exception($sth->errorInfo()[2]);
+		}
+		
+		$results = $sth->fetchAll(\PDO::FETCH_ASSOC);
+		return $results;
+	}
+	
+}
+
+?>
\ No newline at end of file