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QoS Cheatsheet

Quick reference for all 22 DDS QoS policies.

Data Distribution​

PolicyValuesDefaultCompatibility
ReliabilityBestEffort, ReliableBestEffortExact match
HistoryKeepLast(N), KeepAllKeepLast(100)N/A
DurabilityVolatile, TransientLocal, PersistentVolatileWriter >= Reader
DurabilityServiceCleanup delay, history depth, limits-N/A
ResourceLimitsmax_samples, max_instances, max_quota_bytesUnlimitedN/A

Timing​

PolicyValuesDefaultCompatibility
DeadlineDurationInfiniteWriter ≤ Reader
LatencyBudgetDuration0Hint only
LifespanDurationInfiniteWriter >= Reader
TimeBasedFilterDuration0Hint only

Ownership​

PolicyValuesDefaultCompatibility
OwnershipShared, ExclusiveSharedExact match
OwnershipStrengthInteger0N/A

Ordering​

PolicyValuesDefaultCompatibility
DestinationOrderByReception, BySourceByReceptionWriter >= Reader
PresentationInstance, Topic, GroupInstanceWriter >= Reader

Lifecycle​

PolicyValuesDefaultCompatibility
LivelinessAutomatic, ManualByParticipant, ManualByTopicAutomaticWriter >= Reader
WriterDataLifecycleautodispose_unregisteredtrueN/A
ReaderDataLifecycleautopurge delaysInfiniteN/A
EntityFactoryautoenabletrueN/A

Metadata​

PolicyValuesDefaultCompatibility
UserDataBytesEmptyHint only
TopicDataBytesEmptyHint only
GroupDataBytesEmptyHint only
PartitionString listEmpty (default)Intersection
TransportPriorityInteger0Hint only

Common Profiles​

Sensor Streaming (High Rate)​

let qos = DataWriterQos::default()
    .reliability(Reliability::BestEffort)
    .durability(Durability::Volatile)
    .history(History::KeepLast { depth: 1 });

State Synchronization​

let qos = DataWriterQos::default()
    .reliability(Reliability::Reliable {
        max_blocking_time: Duration::from_secs(1),
    })
    .durability(Durability::TransientLocal)
    .history(History::KeepLast { depth: 10 });

Command Queue​

let qos = DataWriterQos::default()
    .reliability(Reliability::Reliable {
        max_blocking_time: Duration::from_secs(30),
    })
    .durability(Durability::Volatile)
    .history(History::KeepAll);

Event Log​

let qos = DataWriterQos::default()
    .reliability(Reliability::Reliable {
        max_blocking_time: Duration::from_secs(5),
    })
    .durability(Durability::Persistent)
    .history(History::KeepAll);

Compatibility Matrix​

Reliability​

WriterReaderMatch
ReliableReliable✅
ReliableBestEffort✅
BestEffortBestEffort✅
BestEffortReliable❌

Durability​

WriterReaderMatch
PersistentAny✅
TransientLocalTransientLocal/Volatile✅
TransientLocalPersistent❌
VolatileVolatile✅
VolatileTransientLocal/Persistent❌

Liveliness​

WriterReaderMatch
ManualByTopicAny✅
ManualByParticipantManualByParticipant/Automatic✅
ManualByParticipantManualByTopic❌
AutomaticAutomatic✅
AutomaticManual*❌

Quick Reference​

Writer QoS​

DataWriterQos::default()
    .reliability(Reliability::Reliable { max_blocking_time })
    .durability(Durability::TransientLocal)
    .history(History::KeepLast { depth: 100 })
    .deadline(Deadline::new(Duration::from_millis(100)))
    .liveliness(Liveliness::Automatic { lease_duration })
    .ownership(Ownership::Shared)
    .resource_limits(ResourceLimits { ... })

Reader QoS​

DataReaderQos::default()
    .reliability(Reliability::Reliable)
    .durability(Durability::TransientLocal)
    .history(History::KeepLast { depth: 50 })
    .deadline(Deadline::new(Duration::from_millis(200)))
    .time_based_filter(TimeBasedFilter::from_millis(10))

Publisher/Subscriber QoS​

PublisherQos::default()
    .partition(Partition::single("sensor"))
    .presentation(Presentation::topic_coherent())

Participant QoS​

DomainParticipantQos::default()
    .user_data(UserData::new(b"version=1.0".to_vec()))

See Also​