ds.granules.operation

Interface Map

All Superinterfaces:

ds.funnel.data.format.FormatMarshaller, MapReduce, Operation

All Known Implementing Classes:

MapReduceBase, StreamBase, StreamProcessor, StreamSource

public interface Map
extends MapReduce

This interface corresponds to the Map role in a Map-Reduce operation. It incorporates support for adding and removing Reduce functions.

Author:

Shrideep Pallickara

Nested Class Summary

Nested classes/interfaces inherited from interface ds.granules.operation.Operation

Operation.OperationType

Method Summary

Methods

Modifier and Type	Method and Description
int	addReduce(Reduce reduce) Adds a Reduce for this particular Map.
int	getNumberOfReducers() Retrieves the number of registered Reduce instances
Enumeration<String>	getReduceIdentifiers() Retrieves the set of Reduce identifiers
int	removeReduce(String reduceIdentifier) Removes a given reducer from the list of Reducers for a given Map function.

Methods inherited from interface ds.granules.operation.MapReduce

createResults, writeResults, writeResults, writeResults, writeResults

Methods inherited from interface ds.granules.operation.Operation

dispose, execute, getDatasetCollection, getDomain, getExecutionProfile, getInstanceIdentifier, getOperationIdentifier, getProcessingDirectives, getVersionInformation, hasDatasetCollection, hasExecutionProfile, hasProcessingDirectives, initialize, isInitialized, needsInitialization, terminationConditionReached, toString, unmarshall

Methods inherited from interface ds.funnel.data.format.FormatMarshaller

marshall

Method Detail

getNumberOfReducers

int getNumberOfReducers()

Retrieves the number of registered Reduce instances

Returns:

The number of reducers for this map.

getReduceIdentifiers

Enumeration<String> getReduceIdentifiers()

Retrieves the set of Reduce identifiers

Returns:

An enumeration of the list of registered identifiers

addReduce

int addReduce(Reduce reduce)
              throws MapReduceException

Adds a Reduce for this particular Map. Typically, a given Map instance will have only one Reduce. There are special instances when multiple Reducers would be needed for a given Map function.

Parameters:

reduce - The Reducer that will be added to this Map

Returns:

The number of reducers for this Map.

Throws:

MapReduceException - If there are problems in adding this Reduce

NullPointerException - If the specified Reduce is null

removeReduce

int removeReduce(String reduceIdentifier)
                 throws MapReduceException

Removes a given reducer from the list of Reducers for a given Map function.

Parameters:

reduceIdentifier - The identifier of the Reduce to be removed

Returns:

The number of reducers for this Map, after the successful removal

Throws:

MapReduceException - If there are problems during removal.

NullPointerException - If the specified Reduce is null