The Zend_Gdata__App_Exception class is a base class
        for exceptions thrown by Zend_Gdata.  You can catch any exception
        thrown by Zend_Gdata by catching Zend_Gdata_App_Exception.
    
<?php
try {
    $client = Zend_Gdata_ClientLogin::getHttpClient($username, $password);
} catch(Zend_Gdata_App_Exception $ex) {
    // Report the exception to the user
    die($ex->getMessage());
}
?>
The following exception subclasses are used by Zend_Gdata:
                    Zend_Gdata_App_AuthException
                    indicates that the user's account credentials were not valid.
                
                    Zend_Gdata_App_BadMethodCallException
                    indicates that a method was called for a service
                    that does not support the method.  For example,
                    the CodeSearch service does not support post().
                
                    Zend_Gdata_App_HttpException
                    indicates that an HTTP request was not successful.  
                    Provides the ability to get the full Zend_Http_Response
                    object to determine the exact cause of the failure in 
                    cases where $e->getMessage() does not provide
                    enough details.
                
                    Zend_Gdata_App_InvalidArgumentException
                    is thrown when the application provides a value that
                    is not valid in a given context.  For example,
                    specifying a Calendar visibility value of "banana",
                    or fetching a Blogger feed without specifying
                    any blog name.
                
You can use these exception subclasses to handle specific exceptions differently. See the API documentation for information on which exception subclasses are thrown by which methods in Zend_Gdata.
<?php
try {
    $client = Zend_Gdata_ClientLogin::getHttpClient($username, $password, $service);
} catch(Zend_Gdata_App_AuthException $authEx) {
    // The user's credentials were incorrect.
    // It would be appropriate to give the user a second try.
    ...
} catch(Zend_Gdata_App_HttpException $httpEx) {
    // Google Data servers cannot be contacted.
    die($httpEx->getMessage);
}
?>