/**
 * Describe Snapshot Attribute Action Sample
 * Returns information about an attribute of a snapshot.
 * Only one attribute can be specified per call.  
 * @param Amazon_EC2_Interface $service instance of Amazon_EC2_Interface
 * @param mixed $request Amazon_EC2_Model_DescribeSnapshotAttribute or array of parameters
 */
function invokeDescribeSnapshotAttribute(Amazon_EC2_Interface $service, $request)
{
    try {
        $response = $service->describeSnapshotAttribute($request);
        echo "Service Response\n";
        echo "=============================================================================\n";
        echo "        DescribeSnapshotAttributeResponse\n";
        if ($response->isSetResponseMetadata()) {
            echo "            ResponseMetadata\n";
            $responseMetadata = $response->getResponseMetadata();
            if ($responseMetadata->isSetRequestId()) {
                echo "                RequestId\n";
                echo "                    " . $responseMetadata->getRequestId() . "\n";
            }
        }
        if ($response->isSetDescribeSnapshotAttributeResult()) {
            echo "            DescribeSnapshotAttributeResult\n";
            $describeSnapshotAttributeResult = $response->getDescribeSnapshotAttributeResult();
            if ($describeSnapshotAttributeResult->isSetSnapshotAttribute()) {
                echo "                SnapshotAttribute\n";
                $snapshotAttribute = $describeSnapshotAttributeResult->getSnapshotAttribute();
                if ($snapshotAttribute->isSetSnapshotId()) {
                    echo "                    SnapshotId\n";
                    echo "                        " . $snapshotAttribute->getSnapshotId() . "\n";
                }
                $createVolumePermissionList = $snapshotAttribute->getCreateVolumePermission();
                foreach ($createVolumePermissionList as $createVolumePermission) {
                    echo "                    CreateVolumePermission\n";
                    if ($createVolumePermission->isSetUserId()) {
                        echo "                        UserId\n";
                        echo "                            " . $createVolumePermission->getUserId() . "\n";
                    }
                    if ($createVolumePermission->isSetGroupName()) {
                        echo "                        GroupName\n";
                        echo "                            " . $createVolumePermission->getGroupName() . "\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";
    }
}