guarana.toolkit.task.routers
Class Filter

java.lang.Object
  extended by guarana.util.observer.smart.SmartObservable
      extended by guarana.framework.task.Task
          extended by guarana.toolkit.task.routers.Router
              extended by guarana.toolkit.task.routers.Filter
All Implemented Interfaces:
ISource, guarana.util.observer.smart.ISmartObserver

public abstract class Filter
extends Router

Removes from the message flow unwanted messages. The filter task may or may not publish an outbound message to the output slot. If log INFO level is activated, a filtered messages causes its MESSAGE_ID to be written to the log. A filter does not change the state of inbound messages. It means the MESSAGE_ID is kept the same!

Graphical notation:


This is an Integration Pattern implementation

Problem: How can a component avoid receiving uninteresting messages?

Solution: Use a special kind of Message Router, a Message Filter, to eliminate undesired messages from a channel based on a set of criteria.

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

Details:

Field Summary
 
Fields inherited from class guarana.framework.task.Task
input, output
 
Constructor Summary
Filter(String name)
          Constructs a new filter task.
Filter(String name, int numberOfInputs, int numberOfOutputs)
          Constructs a new filter task.
 
Method Summary
abstract  void doWork(Exchange exchange)
          This method implements 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
execute, 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

Filter

public Filter(String name)
Constructs a new filter task.

Parameters:
name - The name of the filter task.

Filter

public Filter(String name,
              int numberOfInputs,
              int numberOfOutputs)
Constructs a new filter 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

doWork

public abstract void doWork(Exchange exchange)
                     throws TaskExecutionException
This method implements the business logic of this task.
Filters an inbound message. The filtering policy must be provided by the end user as the implementation of this method.

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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