Package org.oddjob.events

Class When<T>

java.lang.Object

org.oddjob.framework.extend.BaseComponent

org.oddjob.framework.extend.BasePrimary

org.oddjob.framework.extend.StructuralJob<Object>

org.oddjob.events.EventJobBase<T>

org.oddjob.events.When<T>

All Implemented Interfaces:

Serializable, Runnable, Consumer<T>, ArooaContextAware, ArooaSessionAware, Outbound<T>, Forceable, PropertyChangeNotifier, Iconic, LogEnabled, Resettable, Stateful, Stoppable, Structural

public class When<T>
extends EventJobBase<T>

Author:

Rob Gordon.

See Also:

• Serialized Form

Description

Runs a job when triggered by the arrival of an event. The job will be re-run every time the event arrives. If the job is still running when a new event arrives, the job will attempt to be stopped and rerun. A typical use case would be processing a file when it arrives, but which may be re-sent with more up-to-date information.

Example

Evaluating greengrocer portfolios of fruit when data arrives.

<oddjob id="oddjob">

    <job>

        <sequential>

            <jobs>

                <properties name="Properties">

                    <values>

                        <file file="${oddjob.dir}/data" key="data.dir"/>

                    </values>

                </properties>

                <bean class="org.oddjob.events.example.FileFactStore" id="factStore" rootDir="${data.dir}"/>

                <events:when id="whenBookList" name="When BookList Available" xmlns:events="oddjob:events">

                    <jobs>

                        <bean class="org.oddjob.events.example.FactSubscriber" factStore="${factStore}" name="Subscribe to BookList" query="BookList:GREENGROCERS"/>

                        <foreach id="forEachBook" name="For Each Book">

                            <values>

                                <value value="${whenBookList.trigger.of.books}"/>

                            </values>

                            <configuration>

                                <inline>

                                    <foreach id="bookName">

                                        <job>

                                            <events:when id="whenBook" name="When ${bookName.current}">

                                                <jobs>

                                                    <bean class="org.oddjob.events.example.FactSubscriber" factStore="${factStore}" name="Subscribe to Book ${bookName.current}" query="Book:${bookName.current}"/>

                                                    <events:when id="priceMatch" name="When Prices for ${bookName.current}">

                                                        <jobs>

                                                            <events:for name="For Each Trade">

                                                                <configuration>

                                                                    <inline>

                                                                        <events id="trade">

                                                                            <job>

                                                                                <bean class="org.oddjob.events.example.FactSubscriber" factStore="${factStore}" name="Subscribe to Price for ${trade.current.product}" query="Price:${trade.current.product}"/>

                                                                            </job>

                                                                        </events>

                                                                    </inline>

                                                                </configuration>

                                                                <values>

                                                                    <value value="${whenBook.trigger.of.trades}"/>

                                                                </values>

                                                            </events:for>

                                                            <sequential name="Run Calculation">

                                                                <jobs>

                                                                    <bean class="org.oddjob.events.example.ValueCalculator" id="calculate">

                                                                        <trades>

                                                                            <value value="${whenBook.trigger.of.trades}"/>

                                                                        </trades>

                                                                        <prices>

                                                                            <value value="${priceMatch.trigger.ofs}"/>

                                                                        </prices>

                                                                    </bean>

                                                                    <echo>Value of ${bookName.current} is ${calculate.value}</echo>

                                                                </jobs>

                                                            </sequential>

                                                        </jobs>

                                                    </events:when>

                                                </jobs>

                                            </events:when>

                                        </job>

                                    </foreach>

                                </inline>

                            </configuration>

                        </foreach>

                    </jobs>

                </events:when>

            </jobs>

        </sequential>

    </job>

</oddjob>

Being a destination in a pipeline.

<oddjob>

    <job>

        <sequential>

            <jobs>

                <bus:bus xmlns:bus="oddjob:beanbus">

                    <of>

                        <bean class="org.oddjob.events.WhenTest$PretendFileWatcher" id="fileWatcher"/>

                        <bus:filter id="filter">

                            <predicate>

                                <bean class="org.oddjob.events.WhenTest$OnlyTxtFiles"/>

                            </predicate>

                        </bus:filter>

                        <events:when beDestination="true" id="when" xmlns:events="oddjob:events">

                            <jobs>

                                <echo id="result">

                                    Result: ${when.trigger}

                                </echo>

                            </jobs>

                        </events:when>

                    </of>

                </bus:bus>

                <folder>

                    <jobs>

                        <set id="set1" name="Set File Name 1">

                            <values>

                                <value key="fileWatcher.someFileName" value="Fruit.txt"/>

                            </values>

                        </set>

                        <set id="set2" name="Set File Name 2">

                            <values>

                                <value key="fileWatcher.someFileName" value="Names.doc"/>

                            </values>

                        </set>

                        <set id="set3" name="Set File Name 3">

                            <values>

                                <value key="fileWatcher.someFileName" value="Prices.txt"/>

                            </values>

                        </set>

                    </jobs>

                </folder>

            </jobs>

        </sequential>

    </job>

</oddjob>

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	When.Conversions	The Conversion from String
static interface	When.TriggerContext<T>
static enum	When.TriggerStrategies
static interface	When.TriggerStrategy

Field Summary

Fields inherited from class org.oddjob.framework.extend.StructuralJob

childHelper, destroy, stop, structuralState

Constructor Summary

Constructors

Constructor	Description
When()

Method Summary

Modifier and Type	Method	Description
StateCondition	getHaltOn()
When.TriggerStrategy	getTriggerStrategy()
protected void	onImmediateEvent(T event)	Do something with an event received immediately before the subscribe method has returned.
protected void	onLaterEvent(T event, Object job, Executor executor)	Called when an event is received after subscription.
protected void	onSubscriptionStarted(Object job, Executor executor)	Called once the subscription has started.
void	setHaltOn(StateCondition haltOn)
void	setTriggerStrategy(When.TriggerStrategy triggerStrategy)
protected StateListener	stateOnChildComplete()	Used by subclasses to provide a state listener to be added to the child job.

Methods inherited from class org.oddjob.events.EventJobBase

accept, execute, getEventSource, getInitialStateOp, getTo, getTrigger, isBeDestination, onStop, postStop, setBeDestination, setEventSource, setExecutorService, setJobs, setTo, setTrigger, startChildStateReflector, switchToChildStateReflector, unsubscribe

Methods inherited from class org.oddjob.framework.extend.StructuralJob

addStructuralListener, fireDestroyedState, force, getStateChanger, hardReset, iconHelper, isStop, onDestroy, onHardReset, onReset, onSoftReset, removeStructuralListener, run, softReset, stateHandler, stop, stopChildStateReflector, waitForChildrenOnStop

Methods inherited from class org.oddjob.framework.extend.BasePrimary

configure, getName, logger, logger, loggerName, save, setName, toString

Methods inherited from class org.oddjob.framework.extend.BaseComponent

addIconListener, addPropertyChangeListener, addStateListener, configure, destroy, firePropertyChange, getArooaSession, iconForId, initialise, lastStateEvent, onConfigured, onInitialised, removeIconListener, removePropertyChangeListener, removeStateListener, save, setArooaContext, setArooaSession

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.function.Consumer

andThen

Methods inherited from interface org.oddjob.Stateful

addStateListener, lastStateEvent, removeStateListener

Constructor Details

When

public When()

Method Details

onImmediateEvent

protected void onImmediateEvent(T event)

Description copied from class: EventJobBase

Do something with an event received immediately before the subscribe method has returned.

Specified by:

onImmediateEvent in class EventJobBase<T>

Parameters:

event - The event.

onSubscriptionStarted

protected void onSubscriptionStarted(Object job,
 Executor executor)

Description copied from class: EventJobBase

Called once the subscription has started.

Specified by:

onSubscriptionStarted in class EventJobBase<T>

Parameters:

job - The job to execute if any.

executor - The executor to use to execute the job.

onLaterEvent

protected void onLaterEvent(T event,
 Object job,
 Executor executor)

Description copied from class: EventJobBase

Called when an event is received after subscription. There is no guarantee that this will be called after the EventJobBase.onSubscriptionStarted(Object, Executor) method, implementors are responsible for their own synchronisation if required.

Specified by:

onLaterEvent in class EventJobBase<T>

Parameters:

event - The event.

stateOnChildComplete

protected StateListener stateOnChildComplete()

Description copied from class: EventJobBase

Used by subclasses to provide a state listener to be added to the child job.

Specified by:

stateOnChildComplete in class EventJobBase<T>

Returns:

A State Listener. Must not be null.

getTriggerStrategy

public When.TriggerStrategy getTriggerStrategy()

setTriggerStrategy

public void setTriggerStrategy(When.TriggerStrategy triggerStrategy)

getHaltOn

public StateCondition getHaltOn()

setHaltOn

public void setHaltOn(StateCondition haltOn)