Package org.apache.storm.kafka.spout

Class KafkaSpout<K,V>

java.lang.Object
org.apache.storm.topology.base.BaseComponent
org.apache.storm.topology.base.BaseRichSpout
org.apache.storm.kafka.spout.KafkaSpout<K,V>
All Implemented Interfaces:
Serializable, ISpout, IComponent, IRichSpout
public class KafkaSpout<K,V> extends BaseRichSpout
See Also:

  • Field Details

  • Constructor Details

  • Method Details

    • open

      public void open(Map<String,Object> conf, TopologyContext context, SpoutOutputCollector collector)
      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:
      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.

    • 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.

    • ack

      public void ack(Object messageId)
      Description copied from interface: ISpout
      Storm 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.
      Specified by:
      ack in interface ISpout
      Overrides:
      ack in class BaseRichSpout

    • fail

      public void fail(Object messageId)
      Description copied from interface: ISpout
      The 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.
      Specified by:
      fail in interface ISpout
      Overrides:
      fail in class BaseRichSpout

    • activate

      public void activate()
      Description copied from interface: ISpout
      Called 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.
      Specified by:
      activate in interface ISpout
      Overrides:
      activate in class BaseRichSpout

    • deactivate

      public void deactivate()
      Description copied from interface: ISpout
      Called 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.
      Specified by:
      deactivate in interface ISpout
      Overrides:
      deactivate in class BaseRichSpout

    • close

      public void close()
      Description copied from interface: ISpout
      Called 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.

      Specified by:
      close in interface ISpout
      Overrides:
      close in class BaseRichSpout

    • declareOutputFields

      public void declareOutputFields(OutputFieldsDeclarer declarer)
      Description copied from interface: IComponent
      Declare the output schema for all the streams of this topology.
      Parameters:
      declarer - this is used to declare output stream ids, output fields, and whether or not each output stream is a direct stream

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • getComponentConfiguration

      public Map<String,Object> getComponentConfiguration()
      Description copied from interface: IComponent
      Declare 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
      Specified by:
      getComponentConfiguration in interface IComponent
      Overrides:
      getComponentConfiguration in class BaseComponent