I'm trying to create a plugin that gonna let me use the Zoho API via the Zoho PHP SDK. So i created a WP Plugin called connect-zoho and enable it. Until here it's easy :) Then, by CLI i went in my plugin and did : composer requiere zohocrm/php-sdk This installed the vendor folder with the content of zoho php sdk. Now i try to use this SDK inside my plugin wordpress. In my plugin i created a file zoho-initialize-class.php (copy paste from the github doc) : <?php namespace com\zoho\crm\sample\initializer; use com\zoho\api\authenticator\OAuthToken; use com\zoho\api\authenticator\TokenType; use com\zoho\api\authenticator\store\DBStore; use com\zoho\api\authenticator\store\FileStore; use com\zoho\crm\api\Initializer; use com\zoho\crm\api\UserSignature; use com\zoho\crm\api\SDKConfigBuilder; use com\zoho\crm\api\dc\USDataCenter; use com\zoho\api\logger\Logger; use com\zoho\api\logger\Levels; class ZohoInitialize { public static function initialize() { /* * Create an instance of Logger Class that takes two parameters * 1 -> Level of the log messages to be logged. Can be configured by typing Levels "::" and choose any level from the list displayed. * 2 -> Absolute file path, where messages need to be logged. */ $logger = Logger::getInstance(Levels::INFO, "/Users/user_name/Documents/php_sdk_log.log"); //Create an UserSignature instance that takes user Email as parameter $user = new UserSignature("[email protected]"); /* * Configure the environment * which is of the pattern Domain.Environment * Available Domains: USDataCenter, EUDataCenter, INDataCenter, CNDataCenter, AUDataCenter * Available Environments: PRODUCTION(), DEVELOPER(), SANDBOX() */ $environment = USDataCenter::PRODUCTION(); /* * Create a Token instance * 1 -> OAuth client id. * 2 -> OAuth client secret. * 3 -> REFRESH/GRANT token. * 4 -> Token type(REFRESH/GRANT). * 5 -> OAuth redirect URL. */ $token = new OAuthToken("clientId", "clientSecret", "REFRESH/GRANT token", TokenType::REFRESH/GRANT, "redirectURL"); /* * Create an instance of DBStore. * 1 -> DataBase host name. Default value "localhost" * 2 -> DataBase name. Default value "zohooauth" * 3 -> DataBase user name. Default value "root" * 4 -> DataBase password. Default value "" * 5 -> DataBase port number. Default value "3306" */ //$tokenstore = new DBStore(); $tokenstore = new DBStore("hostName", "dataBaseName", "userName", "password", "portNumber"); // $tokenstore = new FileStore("absolute_file_path"); $autoRefreshFields = false; $pickListValidation = false; // Create an instance of SDKConfig $sdkConfig = (new SDKConfigBuilder())->setAutoRefreshFields($autoRefreshFields)->setPickListValidation($pickListValidation)->build(); $resourcePath = "/Users/user_name/Documents/phpsdk-application"; //Create an instance of RequestProxy $requestProxy = new RequestProxy("proxyHost", "proxyPort", "proxyUser", "password"); /* * Call static initialize method of Initializer class that takes the following arguments * 1 -> UserSignature instance * 2 -> Environment instance * 3 -> Token instance * 4 -> TokenStore instance * 5 -> SDKConfig instance * 6 -> resourcePath - A String * 7 -> Log instance (optional) * 8 -> RequestProxy instance (optional) */ Initializer::initialize($user, $environment, $token, $tokenstore, $sdkConfig, $resourcePath, $logger, $requestProxy); } } ?> And then i try to call the function Initialize since my plugin file connect-zoho.php like this: require_once('zoho-initialize-class.php'); ZohoInitialize::initialize(); But i have a problem of namespace and this error : PHP Fatal error: Uncaught Error: Class 'com\zoho\api\logger\Logger' not found in /Users/user/website/zoho/wp-content/plugins/connect-zoho/zoho-initialize-class.php:32 How can i use the SDK inside the plugin ? Thanks