backtype.storm.coordination
Class CoordinatedBolt

java.lang.Object
  extended by backtype.storm.coordination.CoordinatedBolt
All Implemented Interfaces:
IBolt, IComponent, IRichBolt, java.io.Serializable

public class CoordinatedBolt
extends java.lang.Object
implements IRichBolt

Coordination requires the request ids to be globally unique for awhile. This is so it doesn't get confused in the case of retries.

See Also:
Serialized Form

Nested Class Summary
 class CoordinatedBolt.CoordinatedOutputCollector
           
static interface CoordinatedBolt.FinishedCallback
           
static class CoordinatedBolt.IdStreamSpec
           
static class CoordinatedBolt.SourceArgs
           
static interface CoordinatedBolt.TimeoutCallback
           
static class CoordinatedBolt.TrackingInfo
           
 
Field Summary
static Logger LOG
           
 
Constructor Summary
CoordinatedBolt(IRichBolt delegate)
           
CoordinatedBolt(IRichBolt delegate, java.util.Map<java.lang.String,CoordinatedBolt.SourceArgs> sourceArgs, CoordinatedBolt.IdStreamSpec idStreamSpec)
           
CoordinatedBolt(IRichBolt delegate, java.lang.String sourceComponent, CoordinatedBolt.SourceArgs sourceArgs, CoordinatedBolt.IdStreamSpec idStreamSpec)
           
 
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 tuple)
          Process a single tuple of input.
 java.util.Map<java.lang.String,java.lang.Object> getComponentConfiguration()
          Declare configuration specific to this component.
 void prepare(java.util.Map config, TopologyContext context, OutputCollector collector)
          Called when a task for this component is initialized within a worker on the cluster.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

LOG

public static Logger LOG
Constructor Detail

CoordinatedBolt

public CoordinatedBolt(IRichBolt delegate)

CoordinatedBolt

public CoordinatedBolt(IRichBolt delegate,
                       java.lang.String sourceComponent,
                       CoordinatedBolt.SourceArgs sourceArgs,
                       CoordinatedBolt.IdStreamSpec idStreamSpec)

CoordinatedBolt

public CoordinatedBolt(IRichBolt delegate,
                       java.util.Map<java.lang.String,CoordinatedBolt.SourceArgs> sourceArgs,
                       CoordinatedBolt.IdStreamSpec idStreamSpec)
Method Detail

prepare

public void prepare(java.util.Map config,
                    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:

Specified by:
prepare in interface IBolt
Parameters:
config - 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 thread-safe and should be saved as an instance variable of this bolt object.

execute

public void execute(Tuple tuple)
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.

Specified by:
execute in interface IBolt
Parameters:
tuple - 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

declareOutputFields

public void declareOutputFields(OutputFieldsDeclarer declarer)
Description copied from interface: IComponent
Declare the output schema for all the streams of this topology.

Specified by:
declareOutputFields in interface IComponent
Parameters:
declarer - this is used to declare output stream ids, output fields, and whether or not each output stream is a direct stream

getComponentConfiguration

public java.util.Map<java.lang.String,java.lang.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