- Enclosing class:
public static class ExclamationTopology.FixedOrderWordSpout extends BaseRichSpout
- See Also:
Method SummaryModifier and TypeMethodDescription
voidDeclare the output schema for all the streams of this topology.
voidWhen this method is called, Storm is requesting that the Spout emit tuples to the output collector.
voidCalled 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 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
declareOutputFieldspublic void declareOutputFields
(OutputFieldsDeclarer declarer)Description copied from interface:
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 stream
openDescription copied from interface:
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.
nextTuplepublic void nextTuple()Description copied from interface:
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.