guarana.toolkit.task.transformers
Class Aggregator

java.lang.Object
  extended by guarana.util.observer.smart.SmartObservable
      extended by guarana.framework.task.Task
          extended by guarana.toolkit.task.transformers.Transformer
              extended by guarana.toolkit.task.transformers.Aggregator
All Implemented Interfaces:
ISource, guarana.util.observer.smart.ISmartObserver

public abstract class Aggregator
extends Transformer

Constructs a new outbound message from two or more inbound messages produced by an Splitter The header from the first inbound message in the sequence is kept to the outbound message. The outbound message has a new MESSAGE_ID and the inbound messages as parents.

Graphical notation:


This is an Integration Pattern implementation

Problem: How do we combine the results of individual, but related messages so that they can be processed as a whole?

Solution: Use a stateful filter, an Aggregator, to collect and store individual messages until a complete set of related messages has been received. Then, the Aggregator publishes a single message distilled from the individual messages.

Details:

Since:
Guaranį SDK 1.0.0
Author:
Rafael Z. Frantz
See Also:
Aggregator pattern by Gregor Hohpe and Bobby Woolf for more details.

Field Summary
 
Fields inherited from class guarana.framework.task.Task
input, output
 
Constructor Summary
Aggregator(String name)
          Constructs a new aggregator task.
Aggregator(String name, int numberOfInputs, int numberOfOutputs)
          Constructs a new aggregator task.
 
Method Summary
abstract  void doWork(Exchange exchange)
          This method implements the business logic of this task.
 void execute()
          This method executes the business logic of this task.
 void update(guarana.util.observer.smart.SmartObservable slot, Object arg)
          This method is automatically called by the observable slot to notify the slot has received a message.
 
Methods inherited from class guarana.framework.task.Task
getName, getTriggerInterval, isTriggerTask, setName, setTriggerInterval
 
Methods inherited from class guarana.util.observer.smart.SmartObservable
addSmartObserver, containsSmartObserver, containsSmartObserver, countSmartObservers, deleteSmartObserver, deleteSmartObservers, hasChanged, notifySmartObservers, notifySmartObservers
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Aggregator

public Aggregator(String name)
Constructs a new aggregator task.

Parameters:
name - The name of this task.

Aggregator

public Aggregator(String name,
                  int numberOfInputs,
                  int numberOfOutputs)
Constructs a new aggregator task.

Parameters:
name - The name of this task.
numberOfInputs - The number of input gateways this task must have.
numberOfOutputs - The number of output gateways this task must have.
Method Detail

execute

public void execute()
             throws TaskExecutionException
This method executes the business logic of this task. It is automatically invoked by workers.

Overrides:
execute in class Task
Throws:
TaskExecutionException - to report any exception that has occurred during the execution of this method.
See Also:
TaskExecutionException

doWork

public abstract void doWork(Exchange exchange)
                     throws TaskExecutionException
This method implements the business logic of this task.
Aggregates a set of messages into just one message.

Overrides:
doWork in class Task
Parameters:
exchange - An exchange object that holds the inbound messages of this task.
Throws:
TaskExecutionException - to report any exception that has occurred during the execution of this method.

update

public void update(guarana.util.observer.smart.SmartObservable slot,
                   Object arg)
This method is automatically called by the observable slot to notify the slot has received a message. For all those tasks that can execute with one or more messages in its input slots, this method will add the task to the executable task reporter, so it can be executed. In this case the task execution will consume messages from all input slots.
Please, do not call this method by yourself. Overrides the implementation at Task for performance reasons.

Specified by:
update in interface guarana.util.observer.smart.ISmartObserver
Overrides:
update in class Task
Parameters:
slot - The Slot associated with this task.
arg - THIS PARAMETHER IS NOT USED.


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