public class WordSpout extends Object implements IRichSpout
| Constructor and Description |
|---|
WordSpout() |
WordSpout(boolean isDistributed) |
| Modifier and Type | Method and Description |
|---|---|
void |
ack(Object msgId)
Storm has determined that the tuple emitted by this spout with the msgId identifier has been fully processed.
|
void |
activate()
Called when a spout has been activated out of a deactivated mode.
|
void |
close()
Called when an ISpout is going to be shutdown.
|
void |
deactivate()
Called when a spout has been deactivated.
|
void |
declareOutputFields(OutputFieldsDeclarer declarer)
Declare the output schema for all the streams of this topology.
|
void |
fail(Object msgId)
The tuple emitted by this spout with the msgId identifier has failed to be fully processed.
|
Map<String,Object> |
getComponentConfiguration()
Declare configuration specific to this component.
|
boolean |
isDistributed() |
void |
nextTuple()
When this method is called, Storm is requesting that the Spout emit tuples to the output collector.
|
void |
open(Map conf,
TopologyContext context,
SpoutOutputCollector collector)
Called when a task for this component is initialized within a worker on the cluster.
|
public static final String[] words
public boolean isDistributed()
public void open(Map 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:
open in interface ISpoutconf - 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 close()
ISpoutCalled when an ISpout is going to be shutdown. There is no guarentee that close will be called, because the supervisor kill -9’s worker processes on the cluster.
The one context where close is guaranteed to be called is a topology is killed when running Storm in local mode.
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 ack(Object msgId)
ISpoutStorm has determined that the tuple emitted by this spout with the msgId identifier has been fully processed. Typically, an implementation of this method will take that message off the queue and prevent it from being replayed.
public void fail(Object msgId)
ISpoutThe tuple emitted by this spout with the msgId identifier has failed to be fully processed. Typically, an implementation of this method will put that message back on the queue to be replayed at a later time.
public void declareOutputFields(OutputFieldsDeclarer declarer)
IComponentDeclare the output schema for all the streams of this topology.
declareOutputFields in interface IComponentdeclarer - this is used to declare output stream ids, output fields, and whether or not each output stream is a direct streampublic void activate()
ISpoutCalled when a spout has been activated out of a deactivated mode. nextTuple will be called on this spout soon. A spout can become activated after having been deactivated when the topology is manipulated using the storm client.
public void deactivate()
ISpoutCalled when a spout has been deactivated. nextTuple will not be called while a spout is deactivated. The spout may or may not be reactivated in the future.
deactivate in interface ISpoutpublic Map<String,Object> getComponentConfiguration()
IComponentDeclare configuration specific to this component. Only a subset of the “topology.*” configs can be overridden. The component configuration can be further overridden when constructing the topology using TopologyBuilder
getComponentConfiguration in interface IComponentCopyright © 2019 The Apache Software Foundation. All Rights Reserved.