oracle.toplink.dataservices.livedata.qcn

Class QCNSubscription

java.lang.Object

oracle.toplink.dataservices.livedata.Subscription

oracle.toplink.dataservices.livedata.QuerySubscription

oracle.toplink.dataservices.livedata.qcn.QCNSubscription

public class QCNSubscription
extends QuerySubscription

QCNSubscription uses the Oracle DB QCN feature to facilitate Live Data notifications The QCN feature will give us a call back if an update on an underlying Oracle database affects the result of a particular query. We respond the the callback by retrieving the corresponding object and pushing the call to our notifier. We will make the following notifier calls: newObject(object) - for any insert we are informed of updatedObject(object) - for an update that either adds an object to the result set or does not affect the object's presence in the result set. removedObject(primaryKey) - for a delete or for an update that removes an object from the result set. Note: The primary key will only be provided if the deleted object is available in the TopLink cache. Else this callback will be called with null as the argument. This subscription is limited to queries that Oracle QCN can handle. An exception will be thrown at initialization time for queries that do not comply.

Author:

tware

Constructor Summary

Constructors

Constructor and Description
QCNSubscription(DataServicePersistenceContext context, ObjectLevelReadQuery query, java.util.Map<java.lang.String,java.lang.String> parameters)

Method Summary

Methods

Modifier and Type	Method and Description
DataServiceChangeNotificationListener	getDatabaseEventListener()
boolean	isIgnoreOwnTransactions()
void	newObject(java.lang.String queryName, java.lang.String entityName, java.lang.String transactionId, java.lang.String rowId) Retrieve the changed object based on its ROWID.
void	removedObject(java.lang.String queryName, java.lang.String entityName, java.lang.String transactionId, java.lang.String rowId) Attempt to retrieve the removedObject from the cache.
java.lang.Object	retrieveChangedObject(java.lang.String entityName, java.lang.String transactionId, java.lang.String rowId) Search for the object that was changed based on it's rowId
void	setDatabaseEventListener(DataServiceChangeNotificationListener databaseEventListener)
void	setIgnoreOwnTransactions(boolean ignoreOwnTransactions)
void	unsubscribe()
void	updatedObject(java.lang.String queryName, java.lang.String entityName, java.lang.String transactionId, java.lang.String rowId) Retrieve the changed object based on its ROWID.

Methods inherited from class oracle.toplink.dataservices.livedata.QuerySubscription

getParameters, getSubscriptionId

Methods inherited from class oracle.toplink.dataservices.livedata.Subscription

addClientNotifier, getClientNotifiers, getContext, newObject, notifierClosed, removeClientNotifier, removedObject, updatedObject

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

QCNSubscription

public QCNSubscription(DataServicePersistenceContext context,
               ObjectLevelReadQuery query,
               java.util.Map<java.lang.String,java.lang.String> parameters)

Method Detail

getDatabaseEventListener

public DataServiceChangeNotificationListener getDatabaseEventListener()

isIgnoreOwnTransactions

public boolean isIgnoreOwnTransactions()

setDatabaseEventListener

public void setDatabaseEventListener(DataServiceChangeNotificationListener databaseEventListener)

setIgnoreOwnTransactions

public void setIgnoreOwnTransactions(boolean ignoreOwnTransactions)

newObject

public void newObject(java.lang.String queryName,
             java.lang.String entityName,
             java.lang.String transactionId,
             java.lang.String rowId)

Retrieve the changed object based on its ROWID. If a retrieved object is returned, send it through the callback mechanism as a newObject else it is not of interest, ignore it

Parameters:

queryName -

entityName -

transactionId -

rowId -

removedObject

public void removedObject(java.lang.String queryName,
                 java.lang.String entityName,
                 java.lang.String transactionId,
                 java.lang.String rowId)

Attempt to retrieve the removedObject from the cache. If the primary key is available provide it in the callback call, else provide null

Parameters:

queryName -

entityName -

transactionId -

rowId -

updatedObject

public void updatedObject(java.lang.String queryName,
                 java.lang.String entityName,
                 java.lang.String transactionId,
                 java.lang.String rowId)

Retrieve the changed object based on its ROWID. If a retrieved object is returned check whether it conforms to the query before sending it through the callback mechanism. If it conforms send it as an updatedObject else send it as a removedObject. If the object cannot be retrieved, assume the downstream code determined it did not conform.

Parameters:

queryName -

entityName -

transactionId -

rowId -

retrieveChangedObject

public java.lang.Object retrieveChangedObject(java.lang.String entityName,
                                     java.lang.String transactionId,
                                     java.lang.String rowId)

Search for the object that was changed based on it's rowId. - if the object exits in the cache and cacheOnly is true, return it - if it is not in the cache or does not have a transaction id set on it that is equal to the current transaction id, query for it and return it - return null otherwise indicating this object is not one we are interested in

Parameters:

entityName -

transactionId -

rowId -

cacheOnly -

Returns:

unsubscribe

public void unsubscribe()

Specified by:

unsubscribe in class Subscription