/**
 * Start Instances Action Sample
 * Starts an instance that uses an Amazon EBS volume as its root device.
 * Instances that use Amazon EBS volumes as their root devices can be quickly stopped and started.
 * When an instance is stopped, the compute resources are released and you are not billed for hourly
 * instance usage. However, your root partition Amazon EBS volume remains, continues to persist your
 * data, and you are charged for Amazon EBS volume usage. You can restart your instance at any time.  
 * @param Amazon_EC2_Interface $service instance of Amazon_EC2_Interface
 * @param mixed $request Amazon_EC2_Model_StartInstances or array of parameters
 */
function invokeStartInstances(Amazon_EC2_Interface $service, $request)
{
    try {
        $response = $service->startInstances($request);
        echo "Service Response\n";
        echo "=============================================================================\n";
        echo "        StartInstancesResponse\n";
        if ($response->isSetResponseMetadata()) {
            echo "            ResponseMetadata\n";
            $responseMetadata = $response->getResponseMetadata();
            if ($responseMetadata->isSetRequestId()) {
                echo "                RequestId\n";
                echo "                    " . $responseMetadata->getRequestId() . "\n";
            }
        }
        if ($response->isSetStartInstancesResult()) {
            echo "            StartInstancesResult\n";
            $startInstancesResult = $response->getStartInstancesResult();
            $startingInstancesList = $startInstancesResult->getStartingInstances();
            foreach ($startingInstancesList as $startingInstances) {
                echo "                StartingInstances\n";
                if ($startingInstances->isSetInstanceId()) {
                    echo "                    InstanceId\n";
                    echo "                        " . $startingInstances->getInstanceId() . "\n";
                }
                if ($startingInstances->isSetCurrentState()) {
                    echo "                    CurrentState\n";
                    $currentState = $startingInstances->getCurrentState();
                    if ($currentState->isSetCode()) {
                        echo "                        Code\n";
                        echo "                            " . $currentState->getCode() . "\n";
                    }
                    if ($currentState->isSetName()) {
                        echo "                        Name\n";
                        echo "                            " . $currentState->getName() . "\n";
                    }
                }
                if ($startingInstances->isSetPreviousState()) {
                    echo "                    PreviousState\n";
                    $previousState = $startingInstances->getPreviousState();
                    if ($previousState->isSetCode()) {
                        echo "                        Code\n";
                        echo "                            " . $previousState->getCode() . "\n";
                    }
                    if ($previousState->isSetName()) {
                        echo "                        Name\n";
                        echo "                            " . $previousState->getName() . "\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";
    }
}