public class WordGenSpout extends BaseRichSpout
| Constructor and Description |
|---|
WordGenSpout(String file) |
| Modifier and Type | Method and Description |
|---|---|
void |
declareOutputFields(OutputFieldsDeclarer declarer)
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(Map<String,Object> conf,
TopologyContext context,
SpoutOutputCollector collector)
Called when a task for this component is initialized within a worker on the cluster.
|
static ArrayList<String> |
readWords(String file)
Reads text file and extracts words from each line.
|
ack, activate, close, deactivate, failgetComponentConfigurationclone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, waitgetComponentConfigurationpublic static final String FIELDS
public WordGenSpout(String file)
public static ArrayList<String> readWords(String file)
Reads text file and extracts words from each line.
public void open(Map<String,Object> conf, TopologyContext context, SpoutOutputCollector collector)
ISpoutCalled 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:
conf - The Storm configuration for this spout. This is the configuration provided to the topology merged in with cluster configuration on this machine.context - 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.collector - 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.public void nextTuple()
ISpoutWhen 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.
public void declareOutputFields(OutputFieldsDeclarer declarer)
IComponentDeclare the output schema for all the streams of this topology.
declarer - this is used to declare output stream ids, output fields, and whether or not each output stream is a direct streamCopyright © 2020 The Apache Software Foundation. All rights reserved.