Package org.projectbarbel.histo.event

Enum EventType

java.lang.Object

java.lang.Enum<EventType>

org.projectbarbel.histo.event.EventType

All Implemented Interfaces:

Serializable, Comparable<EventType>, PostableEvent

public enum EventType
extends Enum<EventType>
implements PostableEvent

Enum that contains all events thrown by BarbelHisto.

Lifecycle when calling BarbelHisto.save(Object, java.time.ZonedDateTime, java.time.ZonedDateTime) as follows:

 1. BARBELINITIALIZED when BarbelHisto instance is created, only once per BarbelHisto session, both way
 2. INITIALIZEJOURNAL when journal is created, on every update, both way
 3. ACQUIRELOCK, when BarbelHisto starts updating a document journal, synchronous post
 4. INACTIVATION, when versions are inactivated, both way
 5. INSERTBITEMPORAL, when new versions are inserted, both way
 6. UPDATEFINISHED, when the update operation for journal was completed, once per save operation, both way
 7. RELEASELOCK, when BarbelHisto finishes the updating cycle, synchronous post
 

The RETRIEVEDATA event is posted each time when clients retrieve data from BarbelHisto. The ONLOADOPERATION and UNONLOADOPERATION events is posted when the client performs a bulk load and unload with BarbelHisto.load(java.util.Collection) and BarbelHisto.unload(Object...) respectively, both posted both way.

"Both way" means that the event is published synchronously and asynchronously, i.e. clients can register listeners in asynchronous and synchronous bus to catch these events.

Different uses of HistoEvents are possible. For instance clients may want to:

• synchronize data in external data stores with INACTIVATION and INSERTBITEMPORAL
• lock journals stored in a database in complex distributed scenarios using ACQUIRELOCK and RELEASELOCK
• lazy load the backbone from external source depending on the data requested by clients using the RETRIEVEDATA event

To make use of EventType create listener classed like so;

 public class MyListener {
    @Subscribe
    public void handleEvent(AquireLockEvent event) {
       // handle the event
    }
 }
 

Then register the listeners with BarbelHistoBuilder.withSynchronousEventListener(Object) or BarbelHistoBuilder.withAsynchronousEventListener(Object).

If you perform synchronous events, you can control the behavior if the event processing fails. If the handler fails to handle the received synchronous event, then call HistoEvent.failed(Throwable). This will stop execution and an HistoEventFailedException will be thrown without continuing processing. This could be useful in many situations, e.g. in situations where clients want to avoid any inconsistency between the backbone collection and an external data source targeted by an event.

Author:

Niklas Schlimm

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	EventType.AbstractBarbelEvent
static class	EventType.AcquireLockEvent
class	EventType.BarbelInitializedEvent
static class	EventType.DefaultSubscriberExceptionHandler
static class	EventType.InactivationEvent
static class	EventType.InitializeJournalEvent
static class	EventType.InsertBitemporalEvent
class	EventType.OnLoadOperationEvent
static class	EventType.ReleaseLockEvent
static class	EventType.RetrieveDataEvent
class	EventType.UnLoadOperationEvent
static class	EventType.UpdateFinishedEvent

Enum Constant Summary

Enum Constants

Enum Constant	Description
ACQUIRELOCK	Event fired when BarbelHisto acquires the lock for a journal update.
BARBELINITIALIZED	Event fired when BarbelHisto is ready for execution.
INACTIVATION	Event fired when BarbelHisto inactivates versions.
INITIALIZEJOURNAL	Event fired when a journal updated is started on a BarbelHisto.save(Object, java.time.ZonedDateTime, java.time.ZonedDateTime) operation.
INSERTBITEMPORAL	Event fired when BarbelHisto inserts new version data to a document journal for a given document ID.
ONLOADOPERATION	Event fired when client performs load operation with BarbelHisto.load(java.util.Collection).
RELEASELOCK	Event fired when BarbelHisto released a lock on a document journal for a given document ID in the operation.
RETRIEVEDATA	Event fired when BarbelHisto performs a query on request of the client, e.g.
UNONLOADOPERATION	Event fired when client performs unload operation with BarbelHisto.unload(Object...).
UPDATEFINISHED	Event fired when BarbelHisto finished updating the document journal of a given document id.

Method Summary

Modifier and Type	Method	Description
static EventType	valueOf(String name)	Returns the enum constant of this type with the specified name.
static EventType[]	values()	Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.projectbarbel.histo.event.PostableEvent

create

Enum Constant Detail

BARBELINITIALIZED

public static final EventType BARBELINITIALIZED

Event fired when BarbelHisto is ready for execution.

INITIALIZEJOURNAL

public static final EventType INITIALIZEJOURNAL

Event fired when a journal updated is started on a BarbelHisto.save(Object, java.time.ZonedDateTime, java.time.ZonedDateTime) operation.

ACQUIRELOCK

public static final EventType ACQUIRELOCK

Event fired when BarbelHisto acquires the lock for a journal update. Posted once for each save-operation at the beginning of the update-operation.

INSERTBITEMPORAL

public static final EventType INSERTBITEMPORAL

Event fired when BarbelHisto inserts new version data to a document journal for a given document ID. Posted once for each save-operation.

INACTIVATION

public static final EventType INACTIVATION

Event fired when BarbelHisto inactivates versions. Posted once for each save-operation.

UPDATEFINISHED

public static final EventType UPDATEFINISHED

Event fired when BarbelHisto finished updating the document journal of a given document id. Posted once for each save-operation.

RELEASELOCK

public static final EventType RELEASELOCK

Event fired when BarbelHisto released a lock on a document journal for a given document ID in the operation. Posted once for each save-operation at the end of the update-operation

RETRIEVEDATA

public static final EventType RETRIEVEDATA

Event fired when BarbelHisto performs a query on request of the client, e.g. in BarbelHisto.retrieve(Query). Posted once for each retrieve-operation, both way.

ONLOADOPERATION

public static final EventType ONLOADOPERATION

Event fired when client performs load operation with BarbelHisto.load(java.util.Collection). Posted both way.

UNONLOADOPERATION

public static final EventType UNONLOADOPERATION

Event fired when client performs unload operation with BarbelHisto.unload(Object...). Posted both way.

Method Detail

values

public static EventType[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (EventType c : EventType.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static EventType valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null