Connection (Apache HBase 1.4.11 API)

All Superinterfaces:

Abortable, AutoCloseable, Closeable

All Known Subinterfaces:

ClusterConnection, HConnection

All Known Implementing Classes:

CoprocessorHConnection
```
@InterfaceAudience.Public
@InterfaceStability.Evolving
public interface Connection
extends Abortable, Closeable
```
A cluster connection encapsulating lower level individual connections to actual servers and a connection to zookeeper. Connections are instantiated through the ConnectionFactory class. The lifecycle of the connection is managed by the caller, who has to close() the connection to release the resources.
The connection object contains logic to find the master, locate regions out on the cluster, keeps a cache of locations and then knows how to re-calibrate after they move. The individual connections to servers, meta cache, zookeeper connection, etc are all shared by the Table and Admin instances obtained from this connection.
Connection creation is a heavy-weight operation. Connection implementations are thread-safe, so that the client can create a connection once, and share it with different threads. Table and Admin instances, on the other hand, are light-weight and are not thread-safe. Typically, a single connection per client application is instantiated and every thread will obtain its own Table instance. Caching or pooling of Table and Admin is not recommended.
This class replaces HConnection, which is now deprecated.

Since:

0.99.0

See Also:
ConnectionFactory

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`close()`
`Admin`	`getAdmin()` Retrieve an Admin implementation to administer an HBase cluster.
`BufferedMutator`	`getBufferedMutator(BufferedMutatorParams params)` Retrieve a `BufferedMutator` for performing client-side buffering of writes.
`BufferedMutator`	`getBufferedMutator(TableName tableName)` Retrieve a `BufferedMutator` for performing client-side buffering of writes.
`org.apache.hadoop.conf.Configuration`	`getConfiguration()`
`RegionLocator`	`getRegionLocator(TableName tableName)` Retrieve a RegionLocator implementation to inspect region information on a table.
`Table`	`getTable(TableName tableName)` Retrieve a Table implementation for accessing a table.
`Table`	`getTable(TableName tableName, ExecutorService pool)` Retrieve a Table implementation for accessing a table.
`boolean`	`isClosed()` Returns whether the connection is closed or not.

Methods inherited from interface org.apache.hadoop.hbase.Abortable
abort, isAborted

- Method Detail
  - getConfiguration
```
org.apache.hadoop.conf.Configuration getConfiguration()
```
    Returns:
    Configuration instance being used by this Connection instance.
  - getTable
```
Table getTable(TableName tableName)
               throws IOException
```
    Retrieve a Table implementation for accessing a table. The returned Table is not thread safe, a new instance should be created for each using thread. This is a lightweight operation, pooling or caching of the returned Table is neither required nor desired.
    The caller is responsible for calling Table.close() on the returned table instance.
    Since 0.98.1 this method no longer checks table existence. An exception will be thrown if the table does not exist only when the first operation is attempted.
    
    Parameters:
    tableName - the name of the table
    
    Returns:
    a Table to use for interactions with this table
    
    Throws:
    
    IOException
  - getTable
```
Table getTable(TableName tableName,
             ExecutorService pool)
               throws IOException
```
    Retrieve a Table implementation for accessing a table. The returned Table is not thread safe, a new instance should be created for each using thread. This is a lightweight operation, pooling or caching of the returned Table is neither required nor desired.
    The caller is responsible for calling Table.close() on the returned table instance.
    Since 0.98.1 this method no longer checks table existence. An exception will be thrown if the table does not exist only when the first operation is attempted.
    
    Parameters:
    tableName - the name of the table
    pool - The thread pool to use for batch operations, null to use a default pool.
    
    Returns:
    a Table to use for interactions with this table
    
    Throws:
    
    IOException
  - getBufferedMutator
```
BufferedMutator getBufferedMutator(TableName tableName)
                                   throws IOException
```
    Retrieve a BufferedMutator for performing client-side buffering of writes. The BufferedMutator returned by this method is thread-safe. This BufferedMutator will use the Connection's ExecutorService. This object can be used for long lived operations.
    
    The caller is responsible for calling BufferedMutator.close() on the returned BufferedMutator instance.
    
    This accessor will use the connection's ExecutorService and will throw an exception in the main thread when an asynchronous exception occurs.
    
    Parameters:
    tableName - the name of the table
    
    Returns:
    a BufferedMutator for the supplied tableName.
    
    Throws:
    
    IOException
  - getBufferedMutator
```
BufferedMutator getBufferedMutator(BufferedMutatorParams params)
                                   throws IOException
```
    Retrieve a BufferedMutator for performing client-side buffering of writes. The BufferedMutator returned by this method is thread-safe. This object can be used for long lived table operations. The caller is responsible for calling BufferedMutator.close() on the returned BufferedMutator instance.
    
    Parameters:
    params - details on how to instantiate the BufferedMutator.
    
    Returns:
    a BufferedMutator for the supplied tableName.
    
    Throws:
    
    IOException
  - getRegionLocator
```
RegionLocator getRegionLocator(TableName tableName)
                               throws IOException
```
    Retrieve a RegionLocator implementation to inspect region information on a table. The returned RegionLocator is not thread-safe, so a new instance should be created for each using thread. This is a lightweight operation. Pooling or caching of the returned RegionLocator is neither required nor desired.
    The caller is responsible for calling Closeable.close() on the returned RegionLocator instance. RegionLocator needs to be unmanaged
    
    Parameters:
    tableName - Name of the table who's region is to be examined
    
    Returns:
    A RegionLocator instance
    
    Throws:
    
    IOException
  - getAdmin
```
Admin getAdmin()
               throws IOException
```
    Retrieve an Admin implementation to administer an HBase cluster. The returned Admin is not guaranteed to be thread-safe. A new instance should be created for each using thread. This is a lightweight operation. Pooling or caching of the returned Admin is not recommended.
    The caller is responsible for calling Admin.close() on the returned Admin instance.
    
    Returns:
    an Admin instance for cluster administration
    
    Throws:
    
    IOException
  - close
```
void close()
           throws IOException
```
    Specified by:
    
    close in interface AutoCloseable
    
    Specified by:
    
    close in interface Closeable
    
    Throws:
    
    IOException
  - isClosed
```
boolean isClosed()
```
    Returns whether the connection is closed or not.
    
    Returns:
    true if this connection is closed

Interface Connection

Method Summary

Methods inherited from interface org.apache.hadoop.hbase.Abortable

Method Detail

getConfiguration

getTable

getTable

getBufferedMutator

getBufferedMutator

getRegionLocator

getAdmin

close

isClosed