org.esbtools.eventhandler

Interface NotificationRepository

public interface NotificationRepository

Abstracts a transactional backing store and staging area for notifications.

A repository is responsible for handling CRUD and data parsing operations around these objects, in whatever scheme necessary.

Production implementations are expected to be thread safe, even across a network.

Method Summary

Modifier and Type	Method and Description
void	ensureTransactionActive(Notification notification) Throws a descriptive exception if the provided notification is not in an active transaction, or if the current state of its transaction is unknown.
void	markNotificationsProcessedOrFailed(Collection<? extends Notification> notification, Collection<FailedNotification> failures)
List<? extends Notification>	retrieveOldestNotificationsUpTo(int maxNotifications) Retrieves the oldest maxNotifications notifications, oldest first.

Method Detail

retrieveOldestNotificationsUpTo

List<? extends Notification> retrieveOldestNotificationsUpTo(int maxNotifications)
                                                      throws Exception

Retrieves the oldest maxNotifications notifications, oldest first.

Once retrieved, a notification should not be retrieved again, atomically. That is, many threads looking up notifications at the same time should all et a unique non-overlapping sample of the oldest notifications. Subsequent calls should always return a unique set.

Retrieved notifications begin a transaction with those notifications. Calling markNotificationsProcessedOrFailed(Collection, Collection) ends this transaction on the provided notifications. This transaction may end for other reasons, such as a distributed lock failure or timeout, which would cause subsequent calls to retrieve these same notifications again. To determine if a transaction is still active around this, before notifications' document events are added, ensureTransactionActive(Notification) should be called in order to determine if that notification's transaction is lost or has otherwise ended prematurely.

Throws:

Exception

ensureTransactionActive

void ensureTransactionActive(Notification notification)
                      throws Exception

Throws a descriptive exception if the provided notification is not in an active transaction, or if the current state of its transaction is unknown.

Transactions are started when an event is retrieved from retrieveOldestNotificationsUpTo(int).

Transactions can end before published or failure confirmation for a variety of reasons, such as network failure or timeout, depending on the implementation.

Throws:

Exception - if the event does not have an active transaction, and therefore is available for processing from retrieveOldestNotificationsUpTo(int).

markNotificationsProcessedOrFailed

void markNotificationsProcessedOrFailed(Collection<? extends Notification> notification,
                                        Collection<FailedNotification> failures)
                                 throws Exception

Throws:

Exception