rsb

Class Event

java.lang.Object

rsb.Event

public class Event
extends java.lang.Object

Basic event structure exchanged between RSB ports. It is a combination of metadata and the actual data to publish / subscribe to as payload. Events are often caused by other events, which e.g. means that their contained payload was calculated on the payload of one or more other events. To express these relations each event contains a set of EventIds that express the direct causes of the event. This means, transitive event causes are not modeled. Cause handling is inspired by the ideas proposed in: David Luckham, The Power of Events, Addison-Wessley, 2007

Author:

swrede

Constructor Summary

Constructors

Constructor and Description
Event() Construct empty event.
Event(java.lang.Class<?> type)
Event(Scope scope, java.lang.Class<?> type, java.lang.Object data) Creates a new event that can be send to scope.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	addCause(EventId id) Adds the id of one event to the causes of this event.
boolean	equals(java.lang.Object obj)
java.util.Set<EventId>	getCauses() Returns all causing events marked so far.
java.lang.Object	getData()
EventId	getId()
MetaData	getMetaData() Returns a MetaData instance representing the meta data for this event.
java.lang.String	getMethod()
Scope	getScope()
ParticipantId	getSenderId() Deprecated. use getId() instead
long	getSequenceNumber() Deprecated. use getId() instead
java.lang.Class<?>	getType()
int	hashCode()
boolean	isCause(EventId id) Tells whether the id of one event is already marked as a cause of this event.
boolean	removeCause(EventId id) Removes a causing event from the set of causes for this event.
void	setData(java.lang.Object data)
void	setId(EventId id) Sets the id of this event.
void	setId(ParticipantId senderId, long sequenceNumber) Sets all information necessary to generate the EventId of this event.
void	setMethod(java.lang.String method)
void	setScope(Scope scope)
void	setType(java.lang.Class<?> type)
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Event

public Event(Scope scope,
     java.lang.Class<?> type,
     java.lang.Object data)

Creates a new event that can be send to scope.

Parameters:

scope - The scope to which the event will be sent.

type - A class object indicating the class of the data being sent in the event.

data - The actual data that should be sent in the event.

Event

public Event(java.lang.Class<?> type)

Event

public Event()

Construct empty event. Only metadata is initialized.

Method Detail

getType

public java.lang.Class<?> getType()

Returns:

the Java type of the payload, may be null to express a void type where no payload is carried at all.

setType

public void setType(java.lang.Class<?> type)

Parameters:

type - the Java type to set for the Event payload

getData

public java.lang.Object getData()

Returns:

the data

setData

public void setData(java.lang.Object data)

Parameters:

data - the data to set

getScope

public Scope getScope()

Returns:

the scope

setId

public void setId(ParticipantId senderId,
         long sequenceNumber)

Sets all information necessary to generate the EventId of this event. After this call getId() is able to return an id.

Parameters:

senderId - id of the sending participant for this event

sequenceNumber - sequence number within the specified participant

setId

public void setId(EventId id)

Sets the id of this event. Afterwards getId() can return an id.

Parameters:

id - new id to set

getSenderId

public ParticipantId getSenderId()

Deprecated. use getId() instead

Returns the id of the sending participant for this event.

Returns:

sending participant id

Throws:

java.lang.IllegalStateException - the id is not yet defined because the event was not sent by an Informer so far

setScope

public void setScope(Scope scope)

Parameters:

scope - the scope to set

getSequenceNumber

public long getSequenceNumber()

Deprecated. use getId() instead

Returns the sequence number of the informer that sent the event.

Returns:

unique number within one informer that sends an event

Throws:

java.lang.IllegalStateException - the id is not yet defined because the event was not sent by an Informer so far

getId

public EventId getId()

getMetaData

public MetaData getMetaData()

Returns a MetaData instance representing the meta data for this event.

Returns:

meta data of this event, not null

getMethod

public java.lang.String getMethod()

Returns:

the method

setMethod

public void setMethod(java.lang.String method)

Parameters:

method - the method to set

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

addCause

public boolean addCause(EventId id)

Adds the id of one event to the causes of this event. If the set of causing events already contained the given id, this call has no effect.

Parameters:

id - the id of a causing event

Returns:

true if the causes was added, false if it already existed

removeCause

public boolean removeCause(EventId id)

Removes a causing event from the set of causes for this event. If the id was not contained in this set, the call has no effect.

Parameters:

id - of the causing event

Returns:

true if an event with this id was removed from the causes, else false

isCause

public boolean isCause(EventId id)

Tells whether the id of one event is already marked as a cause of this event.

Parameters:

id - id of the event to test causality for

Returns:

true if id is marked as a cause for this event, else false

getCauses

public java.util.Set<EventId> getCauses()

Returns all causing events marked so far.

Returns:

set of causing event ids. Modifications to this set do not affect this event as it is a copy.