simple class which helpful writing webservices

class.responseHandler.php

<?php
class ResponseHandler {
	private static $_instance;
	private $_api_response_code;
	private $_api_response;
	
	// create new instance of class
	public static function singleInstance() {
		if (! self::$_instance) {
			self::$_instance = new self ();
		}
		return self::$_instance;
	}
	private function __construct() {
		$this->_api_response_code = array (
				0 => array (
						'HTTP Response' => 400,
						'Message' => 'Unknown Error' 
				),
				1 => array (
						'HTTP Response' => 200,
						'Message' => 'Success' 
				),
				2 => array (
						'HTTP Response' => 403,
						'Message' => 'HTTPS Required' 
				),
				3 => array (
						'HTTP Response' => 401,
						'Message' => 'Authentication Required' 
				),
				4 => array (
						'HTTP Response' => 401,
						'Message' => 'Authentication Failed' 
				),
				5 => array (
						'HTTP Response' => 404,
						'Message' => 'Invalid Request' 
				),
				6 => array (
						'HTTP Response' => 400,
						'Message' => 'Invalid Response Format' 
				) 
		);
	}
	/**
	 *
	 * @param string $reponseFormate The desired HTTP response content type: [json, html, xml]
	 * @param int $responseCode The desires reponse for api
	 * @param $data $api_response The desired HTTP response data
	 */
	public function deliver($reponseFormate, $responseCode, $data) {
		$response ['code'] = $responseCode;
		$response ['status'] = $this->_api_response_code [$response ['code']] ['HTTP Response'];
		$response ['status_message'] = $this->_api_response_code [$response ['code']] ['Message'];
		$response ['data'] = $data;
		// Return Response to browser. This will exit the script.
		$this->deliver_response ( $reponseFormate, $response );
	}
	/*
	 * @param string $format The desired HTTP response content type: [json, html, xml]
	 * @param string $api_response The desired HTTP response data
	 * @return void
	 */
	function deliver_response($format, $api_response) {
		
		// Define HTTP responses
		$http_response_code = array (
				200 => 'OK',
				400 => 'Bad Request',
				401 => 'Unauthorized',
				403 => 'Forbidden',
				404 => 'Not Found' 
		);
		
		// Set HTTP Response
		@header ( 'HTTP/1.1 ' . $api_response ['status'] . ' ' . $http_response_code [$api_response ['status']] );
		
		// Process different content types
		if (strcasecmp ( $format, 'json' ) == 0) {
			
			// Set HTTP Response Content Type
			header ( 'Content-Type: application/json; charset=utf-8' );
			
			// Format data into a JSON response
			$json_response = json_encode ( $api_response );
			
			// Deliver formatted data
			echo $json_response;
		} elseif (strcasecmp ( $format, 'xml' ) == 0) {
			
			// Set HTTP Response Content Type
			header ( 'Content-Type: application/xml; charset=utf-8' );
			// Format data into an XML response (This is only good at handling string data, not arrays)
			$xml_response = $this->toXml($api_response,'response');
			// Deliver formatted data
			
			echo $xml_response;
		} else {
			// Set HTTP Response Content Type (This is only good at handling string data, not arrays)
			@header ( 'Content-Type: text/html; charset=utf-8' );
			
			// Deliver formatted data
			echo empty ( $api_response ['data'] ) ? $api_response ['status_message'] : $api_response ['data'];
		}
		
		// End script process
		exit ();
	}
	
	/*
	 * The main function for converting to an XML document. Pass in a multi dimensional array and this recrusively 
	 loops through and builds up an XML document.
	 @param array $data @param string $rootNodeName - what you want the root node to be - defaultsto data. 
	 @param SimpleXMLElement $xml - should only be used recursively @return string XML
	 */
	public static function toXml($data, $rootNodeName = 'data', $xml = null) {
		// turn off compatibility mode as simple xml throws a wobbly if you don't.
		if (ini_get ( 'zend.ze1_compatibility_mode' ) == 1) {
			ini_set ( 'zend.ze1_compatibility_mode', 0 );
		}
		
		if ($xml == null) {
			$xml = simplexml_load_string ( "<?xml version='1.0' encoding='utf-8'?><$rootNodeName />" );
		}
		
		// loop through the data passed in.
		foreach ( $data as $key => $value ) {
			// no numeric keys in our xml please!
			if (is_numeric ( $key )) {
				// make string key...
				$key = "unknownNode_" . ( string ) $key;
			}
			
			// replace anything not alpha numeric
			$key = preg_replace ( '/[^a-z]/i', '', $key );
			
			// if there is another array found recrusively call this function
			if (is_array ( $value )) {
				$node = $xml->addChild ( $key );
				// recrusive call.
				ResponseHandler::toXml ( $value, $rootNodeName, $node );
			} else {
				// add single node.
				$value = htmlentities ( $value );
				$xml->addChild ( $key, $value );
			}
		}
		// pass back as string. or simple xml object if you want!
		return $xml->asXML ();
	}
}

?>