backtype.storm.drpc
Class ReturnResults

java.lang.Object
  extended by backtype.storm.topology.base.BaseComponent
      extended by backtype.storm.topology.base.BaseRichBolt
          extended by backtype.storm.drpc.ReturnResults
All Implemented Interfaces:
IBolt, IComponent, IRichBolt, java.io.Serializable

public class ReturnResults
extends BaseRichBolt

See Also:
Serialized Form

Field Summary
static Logger LOG
           
 
Constructor Summary
ReturnResults()
           
 
Method Summary
 void cleanup()
          Called when an IBolt is going to be shutdown.
 void declareOutputFields(OutputFieldsDeclarer declarer)
          Declare the output schema for all the streams of this topology.
 void execute(Tuple input)
          Process a single tuple of input.
 void prepare(java.util.Map stormConf, TopologyContext context, OutputCollector collector)
          Called when a task for this component is initialized within a worker on the cluster.
 
Methods inherited from class backtype.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 backtype.storm.topology.IComponent
getComponentConfiguration
 

Field Detail

LOG

public static final Logger LOG
Constructor Detail

ReturnResults

public ReturnResults()
Method Detail

prepare

public void prepare(java.util.Map stormConf,
                    TopologyContext context,
                    OutputCollector collector)
Description copied from interface: IBolt
Called when a task for this component is initialized within a worker on the cluster. It provides the bolt with the environment in which the bolt executes.

This includes the:

Parameters:
stormConf - The Storm configuration for this bolt. 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 bolt. Tuples can be emitted at any time, including the prepare and cleanup methods. The collector is not thread-safe and should be saved as an instance variable of this bolt object.

execute

public void execute(Tuple input)
Description copied from interface: IBolt
Process a single tuple of input. The Tuple object contains metadata on it about which component/stream/task it came from. The values of the Tuple can be accessed using Tuple#getValue. The IBolt does not have to process the Tuple immediately. It is perfectly fine to hang onto a tuple and process it later (for instance, to do an aggregation or join).

Tuples should be emitted using the OutputCollector provided through the prepare method. It is required that all input tuples are acked or failed at some point using the OutputCollector. Otherwise, Storm will be unable to determine when tuples coming off the spouts have been completed.

For the common case of acking an input tuple at the end of the execute method, see IBasicBolt which automates this.

Parameters:
input - The input tuple to be processed.

cleanup

public void cleanup()
Description copied from interface: IBolt
Called when an IBolt is going to be shutdown. There is no guarentee that cleanup will be called, because the supervisor kill -9's worker processes on the cluster.

The one context where cleanup is guaranteed to be called is when a topology is killed when running Storm in local mode.

Specified by:
cleanup in interface IBolt
Overrides:
cleanup in class BaseRichBolt

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