org.omg.dds.core.policy.History Interface Reference

Specifies the behavior of the Service in the case where the value of a sample changes (one or more times) before it can be successfully communicated to one or more existing subscribers. More...

Inheritance diagram for org.omg.dds.core.policy.History:

Collaboration diagram for org.omg.dds.core.policy.History:

Classes
enum	Kind

Public Member Functions
int	getDepth ()
ServiceEnvironment	getEnvironment ()
Kind	getKind ()
History	withDepth (int depth)
	Copy this policy and override the value of the property. More...
History	withKeepAll ()
History	withKeepLast (int depth)
History	withKind (Kind kind)
	Copy this policy and override the value of the property. More...

Detailed Description

Specifies the behavior of the Service in the case where the value of a sample changes (one or more times) before it can be successfully communicated to one or more existing subscribers.

This QoS policy controls whether the Service should deliver only the most recent value, attempt to deliver all intermediate values, or do something in between. On the publishing side this policy controls the samples that should be maintained by the DataWriter on behalf of existing DataReader entities. The behavior with regards to a DataReader entities discovered after a sample is written is controlled by the org.omg.dds.core.policy.Durability. On the subscribing side it controls the samples that should be maintained until the application "takes" them from the Service via org.omg.dds.sub.DataReader#take().

Concerns: org.omg.dds.topic.Topic, org.omg.dds.sub.DataReader, org.omg.dds.pub.DataWriter

RxO: No

Changeable: No

1. This policy controls the behavior of the Service when the value of an instance changes before it is finally communicated to some of its existing DataReader entities.

2. If the kind is set to Kind#KEEP_LAST, then the Service will only attempt to keep the latest values of the instance and discard the older ones. In this case, the value of depth regulates the maximum number of values (up to and including the most current one) the Service will maintain and deliver. The default (and most common setting) for depth is one, indicating that only the most recent value should be delivered.

3. If the kind is set to Kind#KEEP_ALL, then the Service will attempt to maintain and deliver all the values of the instance to existing subscribers. The resources that the Service can use to keep this history are limited by the settings of the org.omg.dds.core.policy.ResourceLimits. If the limit is reached, then the behavior of the Service will depend on the org.omg.dds.core.policy.Reliability. If the reliability kind is Reliability.Kind#BEST_EFFORT, then the old values will be discarded. If reliability is Reliability.Kind#RELIABLE, then the Service will block the DataWriter until it can deliver the necessary old values to all subscribers.

The setting of HISTORY depth must be consistent with the RESOURCE_LIMITS maxSamplesPerInstance. For these two QoS to be consistent, they must verify that depth <= maxSamplesPerInstance.

See also

Reliability

ResourceLimits

Definition at line 76 of file History.java.

Member Function Documentation

getDepth()

int org.omg.dds.core.policy.History.getDepth

(

)

Returns

the depth

Implemented in org.opensplice.dds.core.policy.HistoryImpl.

getEnvironment()

ServiceEnvironment org.omg.dds.core.DDSObject.getEnvironment ( )

inherited

Returns

the org.omg.dds.core.ServiceEnvironment object that directly or indirectly was used to create this object.

Implemented in org.omg.dds.core.ServiceEnvironment, org.opensplice.dds.sub.ReflectionDataReader< TYPE, OUT_TYPE >, org.opensplice.dds.core.ModifiableTimeImpl, org.opensplice.dds.pub.ReflectionDataWriter< TYPE >, org.opensplice.dds.core.DurationImpl, org.opensplice.dds.topic.ContentFilteredTopicImpl< TYPE >, org.opensplice.dds.sub.ReadConditionImpl< TYPE >, org.opensplice.dds.core.EntityQosImpl< T extends QosPolicy >, org.opensplice.dds.type.TypeSupportImpl< TYPE >, org.opensplice.dds.topic.PublicationBuiltinTopicDataImpl, org.opensplice.dds.topic.SubscriptionBuiltinTopicDataImpl, org.opensplice.dds.topic.TopicBuiltinTopicDataImpl, org.opensplice.dds.domain.DomainParticipantFactoryImpl, org.opensplice.dds.core.QosProviderImpl, org.opensplice.dds.core.status.OfferedIncompatibleQosStatusImpl, org.opensplice.dds.core.status.RequestedIncompatibleQosStatusImpl, org.opensplice.dds.core.InstanceHandleImpl, org.opensplice.dds.core.StatusConditionImpl< T extends Entity<?, ?>, org.opensplice.dds.core.status.LivelinessChangedStatusImpl, org.opensplice.dds.core.status.PublicationMatchedStatusImpl, org.opensplice.dds.core.status.SubscriptionMatchedStatusImpl, org.opensplice.dds.sub.SampleImpl< TYPE >, org.opensplice.dds.core.policy.ShareImpl, org.opensplice.dds.core.status.OfferedDeadlineMissedStatusImpl, org.opensplice.dds.core.status.SampleRejectedStatusImpl, org.opensplice.dds.core.WaitSetImpl, org.opensplice.dds.topic.ParticipantBuiltinTopicDataImpl, org.opensplice.dds.core.status.RequestedDeadlineMissedStatusImpl, org.opensplice.dds.topic.BuiltinTopicKeyImpl, org.opensplice.dds.core.GuardConditionImpl, org.opensplice.dds.core.event.AllDataDisposedEventImpl< TYPE >, org.opensplice.dds.core.policy.QosPolicyCountImpl, org.opensplice.dds.core.status.InconsistentTopicStatusImpl, org.opensplice.dds.core.status.LivelinessLostStatusImpl, org.opensplice.dds.core.status.SampleLostStatusImpl, org.opensplice.dds.core.policy.QosPolicyImpl, org.opensplice.dds.core.status.AllDataDisposedStatusImpl, org.opensplice.dds.core.IllegalArgumentExceptionImpl, org.opensplice.dds.core.InconsistentPolicyExceptionImpl, org.opensplice.dds.core.policy.PolicyFactoryImpl, org.opensplice.dds.core.policy.TypeConsistencyEnforcementImpl, org.opensplice.dds.core.PreconditionNotMetExceptionImpl, org.opensplice.dds.core.AlreadyClosedExceptionImpl, org.opensplice.dds.core.IllegalOperationExceptionImpl, org.opensplice.dds.core.ImmutablePolicyExceptionImpl, org.opensplice.dds.core.NotEnabledExceptionImpl, org.opensplice.dds.core.OutOfResourcesExceptionImpl, org.opensplice.dds.core.DDSExceptionImpl, org.opensplice.dds.core.status.DataAvailableStatusImpl, and org.opensplice.dds.core.status.DataOnReadersStatusImpl.

getKind()

Kind org.omg.dds.core.policy.History.getKind

(

)

Returns

the kind

Implemented in org.opensplice.dds.core.policy.HistoryImpl.

withDepth()

History org.omg.dds.core.policy.History.withDepth

(

int

depth

)

Copy this policy and override the value of the property.

Parameters

depth

Specifies the number of samples of each instance of data (identified by its key) managed by this Entity.

Returns

a new History policy

Implemented in org.opensplice.dds.core.policy.HistoryImpl.

withKeepAll()

History org.omg.dds.core.policy.History.withKeepAll

(

)

Returns

History with keep-all policy

Implemented in org.opensplice.dds.core.policy.HistoryImpl.

withKeepLast()

History org.omg.dds.core.policy.History.withKeepLast

(

int

depth

)

Returns

History with keep-last policy

Implemented in org.opensplice.dds.core.policy.HistoryImpl.

withKind()

History org.omg.dds.core.policy.History.withKind

(

Kind

kind

)

Copy this policy and override the value of the property.

Parameters

kind	Specifies the type of history, which may be KEEP_LAST or KEEP_ALL

Returns

a new History policy

---

The documentation for this interface was generated from the following file:

• java5/common/java/code/org/omg/dds/core/policy/History.java