edu.iu.dsc.tws.examples.compatibility.storm

Class WordCountTopology.WordSpout

java.lang.Object

org.apache.storm.topology.base.BaseComponent

org.apache.storm.topology.base.BaseRichSpout

edu.iu.dsc.tws.examples.compatibility.storm.WordCountTopology.WordSpout

All Implemented Interfaces:

java.io.Serializable, ISpout, IComponent, IRichSpout

Enclosing class:

WordCountTopology

public static class WordCountTopology.WordSpout
extends BaseRichSpout

A spout that emits a random word

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
WordSpout()

Method Summary

Modifier and Type	Method and Description
void	declareOutputFields(OutputFieldsDeclarer outputFieldsDeclarer) Declare the output schema for all the streams of this topology.
void	nextTuple() When this method is called, Storm is requesting that the Spout emit tuples to the output collector.
void	open(java.util.Map map, TopologyContext topologyContext, SpoutOutputCollector spoutOutputCollector) Called when a task for this component is initialized within a worker on the cluster.

Methods inherited from class org.apache.storm.topology.base.BaseRichSpout

ack, activate, close, deactivate, fail

Methods inherited from class org.apache.storm.topology.base.BaseComponent

getComponentConfiguration

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.storm.topology.IComponent

getComponentConfiguration

Constructor Detail

WordSpout

public WordSpout()

Method Detail

declareOutputFields

public void declareOutputFields(OutputFieldsDeclarer outputFieldsDeclarer)

Description copied from interface: IComponent

Declare the output schema for all the streams of this topology.

Parameters:

outputFieldsDeclarer - this is used to declare output stream ids, output fields, and whether or not each output stream is a direct stream

open

public void open(java.util.Map map,
                 TopologyContext topologyContext,
                 SpoutOutputCollector spoutOutputCollector)

Description copied from interface: ISpout

Called when a task for this component is initialized within a worker on the cluster. It provides the spout with the environment in which the spout executes.

This includes the:

Parameters:

map - The Storm configuration for this spout. This is the configuration provided to the topology merged in with cluster configuration on this machine.

topologyContext - This object can be used to get information about this task's place within the topology, including the task id and component id of this task, input and output information, etc.

spoutOutputCollector - The collector is used to emit tuples from this spout. Tuples can be emitted at any time, including the open and close methods. The collector is thread-safe and should be saved as an instance variable of this spout object.

nextTuple

public void nextTuple()

Description copied from interface: ISpout

When this method is called, Storm is requesting that the Spout emit tuples to the output collector. This method should be non-blocking, so if the Spout has no tuples to emit, this method should return. nextTuple, ack, and fail are all called in a tight loop in a single thread in the spout task. When there are no tuples to emit, it is courteous to have nextTuple sleep for a short amount of time (like a single millisecond) so as not to waste too much CPU.