core

class cyclonedds.core.Qos(*policies, base=None)

Bases: object

This class represents a collections of policies. It allows for easy inspection of this set. When you retrieve a Qos object from an entity modifying that object would actually does not change the Qos of the entity. To reflect this Qos objects are immutable.

x == y

Checks if two Qos objects contain the same policies. This is a full comparison, not a match.

x != y

Checks if two Qos objects do not contain the same policies.

p in qos

Check if a Policy p is contained in Qos object qos. You can use all levels of generalization, for example: Policy.History in qos, Policy.History.KeepLast in qos and Policy.History.KeepLast(1) in qos.

qos[p]

Obtain the Policy matched with p from the Qos object, for example: qos[Policy.History] -> Policy.History.KeepAll

iter(x)

The Qos object supports iteration over it’s contents.

len(x)

Return the number of Policies in the Qos object.

str(x)

Human-readable description of the contained Qos policies.

Parameters:

base (Optional[Qos]) –

policies

A sorted tuple of the Policies contained in this Qos object

Type:

Tuple[BasePolicy]

__init__(*policies, base=None)

Initialize a Qos object

Parameters:

• *policies (BasePolicy) – Pass in any number of constructed Policies.

• base (Qos, optional) – Optionally inherit policies from another Qos object. Inherited policies are overwritten by those newly set.

Raises:

• TypeError – If you pass something that is not a Policy or use a base that is not a Qos object this will be treated as a TypeError.

• ValueError – If you pass two overlapping Policies, for example Policy.History.KeepLast(10) and Policy.History.KeepAll this will be treated as a ValueError.

asdict()

Convert a Qos object to a python dictionary.

Returns:

Fully describe the Qos object using a python dictionary with only built-in types (dict, list, string, int, boolean). This format is not guaranteed to stay consistent between cyclonedds versions but can be useful for debugging or use within an application.

Return type:

dict

classmethod fromdict(data)

Convert a python dictionary as generated by asdict() to a Qos object.

Returns:

Note that the format of the python dictionary is not guaranteed between cyclonedds versions thus storing these dictionaries to disk and loading them again is not recommended.

Return type:

Qos

Parameters:

data (dict) –

class cyclonedds.core.Policy(**kwargs)

The Policy class is fully static and should never need to be instantiated.

See also

qoshowto

How to work with Qos and Policy, TODO.

class Reliability(**kwargs)

The Reliability Qos Policy

Examples

>>> Policy.Reliability.BestEffort
>>> Policy.Reliability.Reliable(max_blocking_time=duration(seconds=1))

Reliable

alias of Reliable

class Durability(**kwargs)

The Durability Qos Policy

Examples

>>> Policy.Durability.Volatile
>>> Policy.Durability.TransientLocal
>>> Policy.Durability.Transient
>>> Policy.Durability.Persistent

class History(**kwargs)

The History Qos Policy

Examples

>>> Policy.History.KeepAll
>>> Policy.History.KeepLast(depth=10)

KeepAll

The type of this entity is not publicly specified.

Type:

Tuple[PolicyType, Any]

KeepLast

alias of KeepLast

class ResourceLimits(max_samples=-1, max_instances=-1, max_samples_per_instance=-1)

The ResourceLimits Qos Policy

Examples

>>> Policy.ResourceLimits(
>>>     max_samples=10,
>>>     max_instances=10,
>>>     max_samples_per_instance=2
>>> )

Parameters:

• max_samples (int) –

• max_instances (int) –

• max_samples_per_instance (int) –

max_samples

Max number of samples total.

Type:

int

max_instances

Max number of instances total.

Type:

int

max_samples_per_instance

Max number of samples per instance.

Type:

int

class PresentationAccessScope(**kwargs)

The Presentation Access Scope Qos Policy

Examples

>>> Policy.PresentationAccessScope.Instance(coherent_access=True, ordered_access=False)
>>> Policy.PresentationAccessScope.Topic(coherent_access=True, ordered_access=False)
>>> Policy.PresentationAccessScope.Group(coherent_access=True, ordered_access=False)

Instance

alias of Instance

Topic

alias of Topic

Group

alias of Group

class Lifespan(lifespan)

The Lifespan Qos Policy

Examples

>>> Policy.Lifespan(duration(seconds=2))

Parameters:

lifespan (int) –

lifespan

Expiration time relative to the source timestamp of a sample in nanoseconds.

Type:

int

class Deadline(deadline)

The Deadline Qos Policy

Examples

>>> Policy.Deadline(deadline=duration(seconds=2))

Parameters:

deadline (int) –

deadline

Deadline of a sample in nanoseconds.

Type:

int

class LatencyBudget(budget)

The Latency Budget Qos Policy

Examples

>>> Policy.LatencyBudget(duration(seconds=2))

Parameters:

budget (int) – Latency budget in nanoseconds.

class Ownership(**kwargs)

The Ownership Qos Policy

Examples

>>> Policy.Ownership.Shared
>>> Policy.Ownership.Exclusive

Shared

Type:

Policy.Ownership.Shared

Exclusive

Type:

Policy.Ownership.Exclusive

class OwnershipStrength(strength)

The Ownership Strength Qos Policy

Examples

>>> Policy.OwnershipStrength(strength=2)

Parameters:

strength (int) – Ownership strength as integer.

class Liveliness(**kwargs)

The Liveliness Qos Policy

Examples

>>> Policy.Liveliness.Automatic(lease_duration=duration(seconds=10))
>>> Policy.Liveliness.ManualByParticipant(lease_duration=duration(seconds=10))
>>> Policy.Liveliness.ManualByTopic(lease_duration=duration(seconds=10))

Automatic

alias of Automatic

ManualByParticipant

alias of ManualByParticipant

ManualByTopic

alias of ManualByTopic

class TimeBasedFilter(filter_time)

The TimeBasedFilter Qos Policy

Examples

>>> Policy.TimeBasedFilter(filter_fn=duration(seconds=2))

Parameters:

filter_time (int) –

filter_time

Minimum time between samples in nanoseconds. Use the helper function duration to write the duration in a human readable format.

Type:

int

class Partition(partitions)

The Partition Qos Policy

Examples

>>> Policy.Partition(partitions=["partition_a", "partition_b", "partition_c"])
>>> Policy.Partition(partitions=[f"partition_{i}" for i in range(100)])

Parameters:

partitions (Sequence[str]) –

partitions

Type:

Sequence[str]

class TransportPriority(priority)

The TransportPriority Qos Policy

Examples

>>> Policy.TransportPriority(priority=10)

Parameters:

priority (int) –

priority

Type:

int

class DestinationOrder

The DestinationOrder Qos Policy

Examples

>>> Policy.DestinationOrder.ByReceptionTimestamp
>>> Policy.DestinationOrder.BySourceTimestamp

class WriterDataLifecycle(autodispose)

The WriterDataLifecycle Qos Policy

Examples

>>> Policy.WriterDataLifecycle(autodispose=False)

Parameters:

autodispose (bool) –

autodispose

Type:

bool

class ReaderDataLifecycle(autopurge_nowriter_samples_delay, autopurge_disposed_samples_delay)

The ReaderDataLifecycle Qos Policy

Examples

>>> Policy.ReaderDataLifecycle(
>>>     autopurge_nowriter_samples_delay=duration(minutes=2),
>>>     autopurge_disposed_samples_delay=duration(minutes=5)
>>> )

Parameters:

• autopurge_nowriter_samples_delay (int) –

• autopurge_disposed_samples_delay (int) –

autopurge_nowriter_samples_delay

Type:

bool

autopurge_disposed_samples_delay

Type:

bool

class DurabilityService(cleanup_delay, history, max_samples, max_instances, max_samples_per_instance)

The DurabilityService Qos Policy

Examples

>>> Policy.DurabilityService(
>>>     cleanup_delay=duration(minutes=2.5),
>>>     history=Policy.History.KeepLast(20),
>>>     max_samples=2000,
>>>     max_instances=200,
>>>     max_samples_per_instance=25
>>> )

Parameters:

• cleanup_delay (int) –

• history (Union[Policy.History.KeepAll, KeepLast]) –

• max_samples (int) –

• max_instances (int) –

• max_samples_per_instance (int) –

cleanup_delay

Type:

int

history

Type:

Policy.History.KeepAll, Policy.History.KeepLast

max_samples

Type:

int

max_instances

Type:

int

max_samples_per_instance

Type:

int

class IgnoreLocal(**kwargs)

The IgnoreLocal Qos Policy

Examples

>>> Policy.IgnoreLocal.Nothing
>>> Policy.IgnoreLocal.Participant
>>> Policy.IgnoreLocal.Process

class Userdata(data)

The Userdata Qos Policy

Examples

>>> Policy.Userdata(data=b"Hello, World!")

Parameters:

data (bytes) –

class Topicdata(data)

The Topicdata Qos Policy

Examples

>>> Policy.Topicdata(data=b"Hello, World!")

Parameters:

data (bytes) –

class Groupdata(data)

The Groupdata Qos Policy

Examples

>>> Policy.Groupdata(data=b"Hello, World!")

Parameters:

data (bytes) –

class Property(key, value)

The Property Qos Policy

Examples

>>> Policy.Property(key="host", value="central")

Parameters:

• key (str) –

• value (str) –

class BinaryProperty(key, value)

The BinaryProperty Qos Policy

Examples

>>> Policy.BinaryProperty(key="host", value=b"central")

Parameters:

• key (str) –

• value (bytes) –

class TypeConsistency(**kwargs)

The TypeConsistency Qos Policy

Examples

>>> Policy.TypeConsistency.DisallowTypeCoercion
>>> Policy.TypeConsistency.AllowTypeCoercion

DisallowTypeCoercion

alias of DisallowTypeCoercion

AllowTypeCoercion

alias of AllowTypeCoercion

class DataRepresentation(use_cdrv0_representation=False, use_xcdrv2_representation=False)

The DataRepresentation Qos Policy

Parameters:

• use_cdrv0_representation (bool) –

• use_xcdrv2_representation (bool) –

class EntityName(name)

The EntityName Qos Policy

Parameters:

name (str) –