backtype.storm.spout
Class ShellSpout

java.lang.Object
  backtype.storm.spout.ShellSpout

All Implemented Interfaces:

ISpout, Serializable

Direct Known Subclasses:

RichShellSpout

public class ShellSpout
extends Object
implements ISpout

See Also:

Serialized Form

Field Summary

static org.slf4j.Logger

LOG

Constructor Summary

ShellSpout(ShellComponent component)

ShellSpout(String... command)

Method Summary

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	fail(Object msgId) The tuple emitted by this spout with the msgId identifier has failed to be fully processed.
void	nextTuple() When this method is called, Storm is requesting that the Spout emit tuples to the output collector.
void	open(Map stormConf, TopologyContext context, SpoutOutputCollector 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 org.slf4j.Logger LOG

Constructor Detail

ShellSpout

public ShellSpout(ShellComponent component)

ShellSpout

public ShellSpout(String... command)

Method Detail

open

public void open(Map stormConf,
                 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:

Specified by:

open in interface ISpout

Parameters:

stormConf - 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.

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

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.

Specified by:

nextTuple in interface ISpout

ack

public void ack(Object msgId)

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

fail

public void fail(Object msgId)

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

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

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