result = doFirstThing();
if (result==failed)
{
	rollback transaction;
	return (failed, "Failed because FirstThing failed because of whatever);
}

result = doThing2();
if (result==failed)
{
	rollback transaction;
	return (failed, "failed because thing2 failed");
}

result = doThing3();
if (result==failed)
{
	rollback transaction;
	return (failed, "failed because thing3 failed");
}


//////////////
// cleaner way, using exceptions

try
{
	doFirstThing();
	doThing2();
	doThing3();
}
catch (Exception $ex)
{
	rollback transaction;
	return('failed', "Failed because ".$ex->getMessage());
}