/**
 * Describe Key Pairs Action Sample
 * The DescribeKeyPairs operation returns information about key pairs available to
 * you. If you specify key pairs, information about those key pairs is returned.
 * Otherwise, information for all registered key pairs is returned.  
 * @param Amazon_EC2_Interface $service instance of Amazon_EC2_Interface
 * @param mixed $request Amazon_EC2_Model_DescribeKeyPairs or array of parameters
 */
function invokeDescribeKeyPairs(Amazon_EC2_Interface $service, $request)
{
    try {
        $response = $service->describeKeyPairs($request);
        echo "Service Response\n";
        echo "=============================================================================\n";
        echo "        DescribeKeyPairsResponse\n";
        if ($response->isSetResponseMetadata()) {
            echo "            ResponseMetadata\n";
            $responseMetadata = $response->getResponseMetadata();
            if ($responseMetadata->isSetRequestId()) {
                echo "                RequestId\n";
                echo "                    " . $responseMetadata->getRequestId() . "\n";
            }
        }
        if ($response->isSetDescribeKeyPairsResult()) {
            echo "            DescribeKeyPairsResult\n";
            $describeKeyPairsResult = $response->getDescribeKeyPairsResult();
            $keyPairList = $describeKeyPairsResult->getKeyPair();
            foreach ($keyPairList as $keyPair) {
                echo "                KeyPair\n";
                if ($keyPair->isSetKeyName()) {
                    echo "                    KeyName\n";
                    echo "                        " . $keyPair->getKeyName() . "\n";
                }
                if ($keyPair->isSetKeyFingerprint()) {
                    echo "                    KeyFingerprint\n";
                    echo "                        " . $keyPair->getKeyFingerprint() . "\n";
                }
                if ($keyPair->isSetKeyMaterial()) {
                    echo "                    KeyMaterial\n";
                    echo "                        " . $keyPair->getKeyMaterial() . "\n";
                }
            }
        }
    } catch (Amazon_EC2_Exception $ex) {
        echo "Caught Exception: " . $ex->getMessage() . "\n";
        echo "Response Status Code: " . $ex->getStatusCode() . "\n";
        echo "Error Code: " . $ex->getErrorCode() . "\n";
        echo "Error Type: " . $ex->getErrorType() . "\n";
        echo "Request ID: " . $ex->getRequestId() . "\n";
        echo "XML: " . $ex->getXML() . "\n";
    }
}