backtype.storm.grouping
Interface CustomStreamGrouping

All Superinterfaces:

java.io.Serializable

All Known Implementing Classes:

GlobalGrouping, IdentityGrouping, IndexHashGrouping, NGrouping

public interface CustomStreamGrouping
extends java.io.Serializable

Method Summary

java.util.List<java.lang.Integer>	chooseTasks(int taskId, java.util.List<java.lang.Object> values) This function implements a custom stream grouping.
void	prepare(WorkerTopologyContext context, GlobalStreamId stream, java.util.List<java.lang.Integer> targetTasks) Tells the stream grouping at runtime the tasks in the target bolt.

Method Detail

prepare

void prepare(WorkerTopologyContext context,
             GlobalStreamId stream,
             java.util.List<java.lang.Integer> targetTasks)

Tells the stream grouping at runtime the tasks in the target bolt. This information should be used in chooseTasks to determine the target tasks. It also tells the grouping the metadata on the stream this grouping will be used on.

chooseTasks

java.util.List<java.lang.Integer> chooseTasks(int taskId,
                                              java.util.List<java.lang.Object> values)

This function implements a custom stream grouping. It takes in as input the number of tasks in the target bolt in prepare and returns the tasks to send the tuples to.

Parameters:

values - the values to group on