Event

public class Event

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

Constructors

Event

public Event(Scope scope, Class<?> type, 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(Class<?> type)

Creates a new event with the specified data type but data still being null.

Parameters

type – class object describing the data type

Event

public Event(Class<?> type, Object data)

Creates a new event with the specified data type and contents.

Parameters

• type – class object describing the data type

• data – the data this event shall containg. Must match the declared type

Event

public Event()

Construct empty event. Only metadata is initialized.

Methods

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

equals

public boolean equals(Object obj)

getCauses

public 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.

getData

public Object getData()

Returns

the data

getId

public EventId getId()

Returns the id of the event. This might not work in case the event has not been sent so far as the id is defined while sending.

Throws

IllegalStateException – no id available so far

Returns

event id

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 String getMethod()

Returns

the method

getScope

public Scope getScope()

Returns

the scope

getType

public Class<?> getType()

Returns

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

hashCode

public int hashCode()

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

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

setData

public void setData(Object data)

Parameters

data – the data to set

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

setMethod

public void setMethod(String method)

Parameters

method – the method to set

setScope

public void setScope(Scope scope)

Parameters

scope – the scope to set

setType

public void setType(Class<?> type)

Parameters

type – the Java type to set for the Event payload

toString

public String toString()