NotificationListener (Hive 0.12.0 API)

java.lang.Object
- org.apache.hadoop.hive.metastore.MetaStoreEventListener
- - org.apache.hive.hcatalog.listener.NotificationListener

```
public class NotificationListener
extends MetaStoreEventListener
```
Implementation of MetaStoreEventListener It sends message on two type of topics. One has name of form dbName.tblName On this topic, two kind of messages are sent: add/drop partition and finalize_partition message. Second topic has name "HCAT" and messages sent on it are: add/drop database and add/drop table. All messages also has a property named "HCAT_EVENT" set on them whose value can be used to configure message selector on subscriber side.

Field Summary

Fields
Modifier and Type Field and Description

protected javax.jms.Connection conn

static int NUM_RETRIES

protected java.lang.ThreadLocal<javax.jms.Session> session

Fields
Modifier and Type	Field and Description
`protected javax.jms.Connection`	`conn`
`static int`	`NUM_RETRIES`
`protected java.lang.ThreadLocal<javax.jms.Session>`	`session`

Constructor Summary

Constructors
Constructor and Description

NotificationListener(Configuration conf)
Create message bus connection and session in constructor.

Constructors
Constructor and Description
`NotificationListener(Configuration conf)` Create message bus connection and session in constructor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`protected javax.jms.Connection`	`createConnection()` Create the JMS connection
`protected javax.jms.MessageProducer`	`createProducer(javax.jms.Destination topic)` Create a JMS producer
`protected javax.jms.Session`	`createSession()` Creates a JMS session
`protected javax.jms.Topic`	`createTopic(java.lang.String topicName)` Get the topic object for the topicName
`protected void`	`finalize()`
`protected boolean`	`isConnectionHealthy()` Send a dummy message to probe if the JMS connection is healthy
`void`	`onAddPartition(AddPartitionEvent partitionEvent)`
`void`	`onAlterPartition(AlterPartitionEvent ape)`
`void`	`onAlterTable(AlterTableEvent ate)`
`void`	`onCreateDatabase(CreateDatabaseEvent dbEvent)`
`void`	`onCreateTable(CreateTableEvent tableEvent)`
`void`	`onDropDatabase(DropDatabaseEvent dbEvent)`
`void`	`onDropPartition(DropPartitionEvent partitionEvent)` Send dropped partition notifications.
`void`	`onDropTable(DropTableEvent tableEvent)` Send dropped table notifications.
`void`	`onLoadPartitionDone(LoadPartitionDoneEvent lpde)`
`protected void`	`send(HCatEventMessage hCatEventMessage, java.lang.String topicName)`
`protected void`	`send(HCatEventMessage hCatEventMessage, java.lang.String topicName, int retries)`
`protected void`	`testAndCreateConnection()` Does a health check on the connection by sending a dummy message.

Methods inherited from class org.apache.hadoop.hive.metastore.MetaStoreEventListener
getConf, setConf

Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - conn
```
protected javax.jms.Connection conn
```
  - NUM_RETRIES
```
public static final int NUM_RETRIES
```
    See Also:
    
    Constant Field Values
  - session
```
protected final java.lang.ThreadLocal<javax.jms.Session> session
```
- Constructor Detail
  - NotificationListener
```
public NotificationListener(Configuration conf)
```
    Create message bus connection and session in constructor.
- Method Detail
  - onAddPartition
```
public void onAddPartition(AddPartitionEvent partitionEvent)
                    throws MetaException
```
    Overrides:
    
    onAddPartition in class MetaStoreEventListener
    
    Throws:
    
    MetaException
  - onDropPartition
```
public void onDropPartition(DropPartitionEvent partitionEvent)
                     throws MetaException
```
    Send dropped partition notifications. Subscribers can receive these notifications for a particular table by listening on a topic named "dbName.tableName" with message selector string "HCAT_EVENT" = "DROP_PARTITION".
    TODO: DataNucleus 2.0.3, currently used by the HiveMetaStore for persistence, has been found to throw NPE when serializing objects that contain null. For this reason we override some fields in the StorageDescriptor of this notification. This should be fixed after HIVE-2084 "Upgrade datanucleus from 2.0.3 to 3.0.1" is resolved.
    
    Overrides:
    
    onDropPartition in class MetaStoreEventListener
    
    Parameters:
    
    partitionEvent - partition event
    
    Throws:
    
    MetaException
  - onCreateDatabase
```
public void onCreateDatabase(CreateDatabaseEvent dbEvent)
                      throws MetaException
```
    Overrides:
    
    onCreateDatabase in class MetaStoreEventListener
    
    Parameters:
    
    dbEvent - database event
    
    Throws:
    
    MetaException
  - onDropDatabase
```
public void onDropDatabase(DropDatabaseEvent dbEvent)
                    throws MetaException
```
    Overrides:
    
    onDropDatabase in class MetaStoreEventListener
    
    Parameters:
    
    dbEvent - database event
    
    Throws:
    
    MetaException
  - onCreateTable
```
public void onCreateTable(CreateTableEvent tableEvent)
                   throws MetaException
```
    Overrides:
    
    onCreateTable in class MetaStoreEventListener
    
    Parameters:
    
    tableEvent - table event.
    
    Throws:
    
    MetaException
  - onDropTable
```
public void onDropTable(DropTableEvent tableEvent)
                 throws MetaException
```
    Send dropped table notifications. Subscribers can receive these notifications for dropped tables by listening on topic "HCAT" with message selector string "HCAT_EVENT" = "DROP_TABLE"
    TODO: DataNucleus 2.0.3, currently used by the HiveMetaStore for persistence, has been found to throw NPE when serializing objects that contain null. For this reason we override some fields in the StorageDescriptor of this notification. This should be fixed after HIVE-2084 "Upgrade datanucleus from 2.0.3 to 3.0.1" is resolved.
    
    Overrides:
    
    onDropTable in class MetaStoreEventListener
    
    Parameters:
    
    tableEvent - table event.
    
    Throws:
    
    MetaException
  - send
```
protected void send(HCatEventMessage hCatEventMessage,
                    java.lang.String topicName)
```
    Parameters:
    
    hCatEventMessage - The HCatEventMessage being sent over JMS.
    
    topicName - is the name on message broker on which message is sent.
  - send
```
protected void send(HCatEventMessage hCatEventMessage,
                    java.lang.String topicName,
                    int retries)
```
    Parameters:
    
    hCatEventMessage - The HCatEventMessage being sent over JMS, this method is threadsafe
    
    topicName - is the name on message broker on which message is sent.
    
    retries - the number of retry attempts
  - createTopic
```
protected javax.jms.Topic createTopic(java.lang.String topicName)
                               throws javax.jms.JMSException
```
    Get the topic object for the topicName
    
    Parameters:
    
    topicName - The String identifying the message-topic.
    
    Returns:
    
    A Topic object corresponding to the specified topicName.
    
    Throws:
    
    javax.jms.JMSException
  - testAndCreateConnection
```
protected void testAndCreateConnection()
```
    Does a health check on the connection by sending a dummy message. Create the connection if the connection is found to be bad Also recreates the session
  - createConnection
```
protected javax.jms.Connection createConnection()
```
    Create the JMS connection
    
    Returns:
    
    newly created JMS connection
  - isConnectionHealthy
```
protected boolean isConnectionHealthy()
```
    Send a dummy message to probe if the JMS connection is healthy
    
    Returns:
    
    true if connection is healthy, false otherwise
  - createSession
```
protected javax.jms.Session createSession()
                                   throws javax.jms.JMSException
```
    Creates a JMS session
    
    Returns:
    
    newly create JMS session
    
    Throws:
    
    javax.jms.JMSException
  - createProducer
```
protected javax.jms.MessageProducer createProducer(javax.jms.Destination topic)
                                            throws javax.jms.JMSException
```
    Create a JMS producer
    
    Parameters:
    
    topic -
    
    Returns:
    
    newly created message producer
    
    Throws:
    
    javax.jms.JMSException
  - finalize
```
protected void finalize()
                 throws java.lang.Throwable
```
    Overrides:
    
    finalize in class java.lang.Object
    
    Throws:
    
    java.lang.Throwable
  - onLoadPartitionDone
```
public void onLoadPartitionDone(LoadPartitionDoneEvent lpde)
                         throws MetaException
```
    Overrides:
    
    onLoadPartitionDone in class MetaStoreEventListener
    
    Throws:
    
    MetaException
  - onAlterPartition
```
public void onAlterPartition(AlterPartitionEvent ape)
                      throws MetaException
```
    Overrides:
    
    onAlterPartition in class MetaStoreEventListener
    
    Parameters:
    
    ape - partition event
    
    Throws:
    
    MetaException
  - onAlterTable
```
public void onAlterTable(AlterTableEvent ate)
                  throws MetaException
```
    Overrides:
    
    onAlterTable in class MetaStoreEventListener
    
    Parameters:
    
    ate - alter table event
    
    Throws:
    
    MetaException

Class NotificationListener

Field Summary

Constructor Summary

Method Summary

Methods inherited from class org.apache.hadoop.hive.metastore.MetaStoreEventListener

Methods inherited from class java.lang.Object

Field Detail

conn

NUM_RETRIES

session

Constructor Detail

NotificationListener

Method Detail

onAddPartition

onDropPartition

onCreateDatabase

onDropDatabase

onCreateTable

onDropTable

send

send

createTopic

testAndCreateConnection

createConnection

isConnectionHealthy

createSession

createProducer

finalize

onLoadPartitionDone

onAlterPartition

onAlterTable