org.mule.transport.polling.watermark
Class Watermark

java.lang.Object
  org.mule.transport.polling.MessageProcessorPollingOverride
      org.mule.transport.polling.watermark.Watermark

Direct Known Subclasses:

SelectorWatermark, UpdateExpressionWatermark

public abstract class Watermark
extends MessageProcessorPollingOverride

Poll override that provides watermarking functionality: It enriches the event passed to the polling message processor to have a flow variable fetched from the object store defined, ensures the variable is carried over to the flow event if it is going to be executed, and saves the value of the variable back to the object store at the end of the flow.

A limitation of this implementation is that the poll must be embedded into a synchronous flow. An exception will be thrown if this is not the case.

Since:

3.5.0

Field Summary

protected Map<QName,Object>

annotations The watermark annotations added to the definition

Constructor Summary

Watermark(ObjectStore<Serializable> objectStore, String variable, String defaultExpression)

Method Summary

protected abstract Object	getUpdatedValue(MuleEvent event) This method is executed once the flow containing the poll has been executed.
void	putInto(MuleEvent event) Retrieves the watermark value from the underlying peristent store and enriches the event.If there is no value stored, a default expression will be used to create a new one.
protected String	resolveVariable(MuleEvent event)
void	updateFrom(MuleEvent event) Updates the watermark in persistent storage based on the flow variable defined in the event
void	updateWith(MuleEvent event, Serializable newValue)

Methods inherited from class org.mule.transport.polling.MessageProcessorPollingOverride

interceptor

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

annotations

protected Map<QName,Object> annotations

The watermark annotations added to the definition

Constructor Detail

Watermark

public Watermark(ObjectStore<Serializable> objectStore,
                 String variable,
                 String defaultExpression)

Method Detail

resolveVariable

protected String resolveVariable(MuleEvent event)

putInto

public void putInto(MuleEvent event)
             throws ObjectStoreException

Retrieves the watermark value from the underlying peristent store and enriches the event.If there is no value stored, a default expression will be used to create a new one.

Throws:

ObjectStoreException

updateWith

public final void updateWith(MuleEvent event,
                             Serializable newValue)
                      throws ObjectStoreException

Throws:

ObjectStoreException

updateFrom

public final void updateFrom(MuleEvent event)
                      throws ObjectStoreException

Updates the watermark in persistent storage based on the flow variable defined in the event

Parameters:

event - The event containing the watermark as a flow variable

Throws:

ObjectStoreException

getUpdatedValue

protected abstract Object getUpdatedValue(MuleEvent event)

This method is executed once the flow containing the poll has been executed. This method must return the watermark's new value

Parameters:

event - the MuleEvent that was returned by the owning flow

Returns:

the new watermark value