class SelfCheckingResourceChecker implements

string getResource() Return Value string The file

bool isFresh(int $timestamp) Returns true if the resource has not been updated since the given

interface SelfCheckingResourceInterface implements

class FileResource implements

string getResource() Return Value string The file

interface ResourceInterface ResourceInterface is the interface that must be implemented by all

bool isFresh(ResourceInterface

class FileExistenceResource implements

serialize()