Zend_Config_Xml enables developers to store configuration data in a simple XML format and read them via nested object property syntax. The root element of the XML file or string is irrelevant and may be named arbitrarily. The first level of XML elements correspond with configuration data sections. The XML format supports hierarchical organization through nesting of XML elements below the section-level elements. The content of a leaf-level XML element corresponds to the value of a configuration datum. Section inheritance is supported by a special XML attribute named extends, and the value of this attribute corresponds with the section from which data are to be inherited by the extending section. Configuration data read into Zend_Config_Xml are always returned as strings. Conversion of data from strings to other types is left to developers to suit their particular needs. This example illustrates a basic use of Zend_Config_Xml for loading configuration data from an XML file. In this example there are configuration data for both a production system and for a staging system. Because the staging system configuration data are very similar to those for production, the staging section inherits from the production section. In this case, the decision is arbitrary and could have been written conversely, with the production section inheriting from the staging section, though this may not be the case for more complex situations. Suppose, then, that the following configuration data are contained in /path/to/config.xml: www.example.com pdo_mysql db.example.com dbuser secret dbname dev.example.com devuser devsecret ]]> Next, assume that the application developer needs the staging configuration data from the XML file. It is a simple matter to load these data by specifying the XML file and the staging section: database->params->host; // prints "dev.example.com" echo $config->database->params->dbname; // prints "dbname" ]]> Zend_Config_Xml also supports two additional ways of defining nodes in the configuration. Both make use of attributes. Since the extends and the value attributes are reserved keywords (the latter one by the the second way of using attributes), they may not be used. The first way of making usage of attributes is to add attributes in a parent node, which then will be translated into children of that node: ]]> The other way does not really shorten the config, but keeps it easier to maintain since you don't have to write the tag name twice. You simply create an empty tag with the value in the value attribute: www.example.com ]]> Zend_Config_Xml is able to load an XML string directly, such as that retrieved from a database. The string is passed as the first parameter to the constructor and must start with the characters '<?xml': EOT; $config = new Zend_Config_Xml($string, 'staging'); ]]>