com.crankuptheamps.client

Interface BookmarkStore

All Superinterfaces:

java.lang.AutoCloseable

All Known Implementing Classes:

DefaultBookmarkStore, LoggedBookmarkStore, MemoryBookmarkStore, RingBookmarkStore

public interface BookmarkStore
extends java.lang.AutoCloseable

Defines the interface for bookmark stores, which are used by the Client to provide resumable subscriptions and client-side duplicate message handling. This method involves a resource cleanup since it extends AutoCloseable.

Method Summary

Modifier and Type	Method and Description
void	discard(Field subId, long bookmarkSeqNo) You can call this when you want to mark the message specified by the subscription ID and the bookmark sequence number as discarded, indicating that the application has completed processing the message.
void	discard(Message message) You can call this when you want to mark the provided message as discarded, indicating that the application has completed processing the message.
Field	getMostRecent(Field subID) You can call this when you want to return the correct recovery point for resubscription of the provided subID from the BookmarkStore.
Field	getMostRecent(Field subID, boolean useList) You can call this when you want to return the correct recovery point for resubscription of the provided subID from the BookmarkStore.
long	getOldestBookmarkSeq(Field subId) You can call this when you want to retrieve the sequence number of the oldest bookmark in the store.
boolean	isDiscarded(Message message) Called internally by the AMPS Client.
long	log(Message message) Called internally by the AMPS Client to log a bookmark to the persistent log.
void	persisted(Field subId, BookmarkField bookmark) Called internally by the AMPS Client to record the last persisted message in the transaction log of the connected AMPS server to all of its sync replication destinations.
void	persisted(Field subId, long bookmarkSeqNo) Deprecated. use persisted(Field, BookmarkField) instead.
void	purge() You can call this when you want to purge the contents of this store.
void	purge(Field subId) You can call this when you want to purge the contents of this store for a given subscription ID.
void	setResizeHandler(BookmarkStoreResizeHandler handler) You can call this when you want to set a resize handler that is invoked when the store needs to resize.
void	setServerVersion(int version_) Called internally by the AMPS Client when connected to an AMPS server to indicate what version the server is.

Methods inherited from interface java.lang.AutoCloseable

close

Method Detail

log

long log(Message message)
  throws AMPSException

Called internally by the AMPS Client to log a bookmark to the persistent log.

Parameters:

message - The message containing the bookmark to log.

Returns:

the corresponding bookmark sequence number for this bookmark.

Throws:

AMPSException - Thrown when the message cannot be logged.

discard

void discard(Field subId,
             long bookmarkSeqNo)
      throws AMPSException

You can call this when you want to mark the message specified by the subscription ID and the bookmark sequence number as discarded, indicating that the application has completed processing the message. Marking a message as discarded means that the message will not be replayed when the subscription resumes. Recommended to use discard(Message) instead for better performance. It is more efficient because it operates directly on a message object, eliminating the need to specify a subscription ID and bookmark sequence number separately.

Parameters:

subId - The subscription ID of the bookmark.

bookmarkSeqNo - The bookmark sequence number.

Throws:

AMPSException - Thrown when the specified bookmark cannot be discarded.

discard

void discard(Message message)
      throws AMPSException

You can call this when you want to mark the provided message as discarded, indicating that the application has completed processing the message. Marking a message as discarded means the message will not be replayed when the subscription resumes which helps in preventing redundant processing of messages. For optimum performance, it is critical to discard every message once its processing is complete. If a message is never discarded, it remains in the bookmark store.

Parameters:

message - Message to be marked as discarded.

Throws:

AMPSException - Thrown when the specified message cannot be discarded.

getMostRecent

Field getMostRecent(Field subID)
             throws AMPSException

You can call this when you want to return the correct recovery point for resubscription of the provided subID from the BookmarkStore. This is a single bookmark or (more often) a comma-delimited list of bookmarks.

Parameters:

subID - The subscription ID of the most recent bookmark.

Returns:

A Field containing the correct recovery point to use for resubscriptions.

Throws:

AMPSException - Thrown when the store cannot produce a recovery point for the specified subID.

getMostRecent

Field getMostRecent(Field subID,
                    boolean useList)
             throws AMPSException

You can call this when you want to return the correct recovery point for resubscription of the provided subID from the BookmarkStore. This is a single bookmark or (more often) a comma-delimited list of bookmarks. The useList parameter is a boolean flag. When set to true (which is the default), it affects how the recovery point is determined when the store hasn't received any persisted acknowledgments (acks). Specifically, if set to true, the method will build a list of bookmarks based on the last discarded message for each publisher. If set to false, it won't consider this additional information. This option can be useful when persisted acks are not available, allowing you to make more informed decisions about where to resume message processing.

Parameters:

subID - The subscription ID of the most recent bookmark.

useList - In the case where the store has not received any persisted acks, it will build a list of bookmarks based on the last discarded for each publisher if true (default).

Returns:

A Field containing the correct recovery point to use for resubscriptions.

Throws:

AMPSException - Thrown when the store cannot produce a recovery point for the specified subID.

isDiscarded

boolean isDiscarded(Message message)
             throws AMPSException

Called internally by the AMPS Client. This method is called for each arriving message to determine if the application has already processed and discarded this message. This step is crucial to avoid processing the same message multiple times. Returns 'true' if the bookmark is in the log and marked as discarded and should therefore not be reprocessed. Otherwise, returns 'false' indicating that the message is new or hasn't been marked as discarded yet. Generally, isDiscarded is called by the AMPS Client however, there might be situations where the application needs to manually check if a message has been discarded. In such cases, the application can call this method to make that determination.

Parameters:

message - Incoming message used to determine if the application has already processed and discarded the message.

Returns:

Whether the message is already in the store and marked as discarded.

Throws:

AMPSException - Thrown when the store cannot determine if the message is discarded.

purge

void purge()
    throws AMPSException

You can call this when you want to purge the contents of this store. Removes any tracking history associated with publishers and received messages, and may delete or truncate on-disk representations as well. NOTE: This should only be called when there are no ongoing or active subscriptions (i.e. before any subscribe or after all subscriptions are unsubscribed). Purging while subscriptions are active can disrupt those processes.

Throws:

AMPSException - Thrown if the store is unable to remove the contents.

purge

void purge(Field subId)
    throws AMPSException

You can call this when you want to purge the contents of this store for a given subscription ID. Removes any tracking history associated with publishers and received messages, and may delete or truncate on-disk representations as well. NOTE: This should only be called when the specified subscription isn't active (i.e. before it's subscribed or after it's unsubscribed). This method is more specific as compared to 'purge' method and clears data for a particular subscription identified by subId.

Parameters:

subId - The identifier of the subscription to purge. This tells the method which subscription's data to clear.

Throws:

AMPSException - Thrown if the store is unable to remove information for the subscription.

setResizeHandler

void setResizeHandler(BookmarkStoreResizeHandler handler)

You can call this when you want to set a resize handler that is invoked when the store needs to resize. This method allows you to set a custom function that gets called when a bookmark store needs to resize, giving you control and flexibility over how your application responds to this event.

Parameters:

handler - The handler to invoke for the resize.

getOldestBookmarkSeq

long getOldestBookmarkSeq(Field subId)
                   throws AMPSException

You can call this when you want to retrieve the sequence number of the oldest bookmark in the store.

Parameters:

subId - The subscription ID for the oldest bookmark in the store.

Returns:

The internal sequence number of the oldest bookmark in the store.

Throws:

AMPSException - Thrown if the operation of retrieving the oldest bookmark sequence number encounters an issue or fails.

persisted

void persisted(Field subId,
               BookmarkField bookmark)
        throws AMPSException

Called internally by the AMPS Client to record the last persisted message in the transaction log of the connected AMPS server to all of its sync replication destinations.

Parameters:

subId - The subscription ID for the message.

bookmark - The bookmark containing the message.

Throws:

AMPSException - Thrown if the store is unable to record information in the store.

persisted

@Deprecated
void persisted(Field subId,
                           long bookmarkSeqNo)
                    throws AMPSException

Deprecated. use persisted(Field, BookmarkField) instead.

Old style of setting a persisted bookmark no longer used.

Parameters:

subId - The subscription ID for the message.

bookmarkSeqNo - The bookmark sequence number.

Throws:

AMPSException - Thrown if the store is unable to record information in the store.

setServerVersion

void setServerVersion(int version_)

Called internally by the AMPS Client when connected to an AMPS server to indicate what version the server is. A bookmark store can modify behavior based on the version of the server.

Parameters:

version_ - The version of the AMPS server.