cascading.tap
Class SinkTap

java.lang.Object
  extended by cascading.tap.Tap
      extended by cascading.tap.SinkTap
All Implemented Interfaces:
FlowElement, Serializable
Direct Known Subclasses:
MultiSinkTap, TemplateTap

public abstract class SinkTap
extends Tap

Class SinkTap is the base class for TemplateTap. Some Tap instances may only be sinks (as opposed to being a source). These types should subclass SinkTap for convenience.

See Also:
Serialized Form

Constructor Summary
protected SinkTap()
           
protected SinkTap(Scheme scheme)
           
protected SinkTap(Scheme scheme, SinkMode sinkMode)
           
 
Method Summary
 Fields getSourceFields()
          Method getSourceFields returns the sourceFields of this Tap object.
 boolean isSource()
          Method isSource returns true if this Tap instance can be used as a source.
 TupleEntryIterator openForRead(JobConf conf)
          Method openForRead opens the resource represented by this Tap instance.
 TupleEntryCollector openForWrite(JobConf conf)
          Method openForWrite opens the resource represented by this Tap instance.
 Tuple source(Object key, Object value)
          Method source returns the source value as an instance of Tuple
 void sourceInit(JobConf conf)
          Method sourceInit initializes this instance as a source.
 
Methods inherited from class cascading.tap.Tap
deletePath, equals, flowInit, getIdentifier, getPath, getPathModified, getQualifiedPath, getScheme, getSinkFields, getSinkMode, hashCode, isAppend, isEquivalentTo, isKeep, isReplace, isSink, isUpdate, isWriteDirect, makeDirs, outgoingScopeFor, pathExists, resolveFields, resolveIncomingOperationFields, setScheme, setWriteDirect, sink, sinkInit, taps
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

SinkTap

protected SinkTap()

SinkTap

protected SinkTap(Scheme scheme)

SinkTap

protected SinkTap(Scheme scheme,
                  SinkMode sinkMode)
Method Detail

getSourceFields

public Fields getSourceFields()
Description copied from class: Tap
Method getSourceFields returns the sourceFields of this Tap object.

Overrides:
getSourceFields in class Tap
Returns:
the sourceFields (type Fields) of this Tap object.

source

public Tuple source(Object key,
                    Object value)
Description copied from class: Tap
Method source returns the source value as an instance of Tuple

Overrides:
source in class Tap
Parameters:
key - of type WritableComparable
value - of type Writable
Returns:
Tuple

isSource

public boolean isSource()
Description copied from class: Tap
Method isSource returns true if this Tap instance can be used as a source.

Overrides:
isSource in class Tap
Returns:
boolean

openForRead

public TupleEntryIterator openForRead(JobConf conf)
                               throws IOException
Description copied from class: Tap
Method openForRead opens the resource represented by this Tap instance.

Specified by:
openForRead in class Tap
Parameters:
conf - of type JobConf
Returns:
TupleEntryIterator
Throws:
IOException - when the resource cannot be opened

openForWrite

public TupleEntryCollector openForWrite(JobConf conf)
                                 throws IOException
Description copied from class: Tap
Method openForWrite opens the resource represented by this Tap instance.

Specified by:
openForWrite in class Tap
Parameters:
conf - of type JobConf
Returns:
TupleEntryCollector
Throws:
IOException - when

sourceInit

public void sourceInit(JobConf conf)
                throws IOException
Description copied from class: Tap
Method sourceInit initializes this instance as a source.

This method maybe called more than once if this Tap instance is used outside the scope of a Flow instance or if it participates in multiple times in a given Flow or across different Flows in a Cascade.

In the context of a Flow, it will be called after FlowListener.onStarting(cascading.flow.Flow)

Overrides:
sourceInit in class Tap
Parameters:
conf - of type JobConf
Throws:
IOException - on resource initialization failure.


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