DDS_DomainParticipantResourceLimitsQosPolicy Struct Reference

<<cert>> Resource limits that apply only to DDSDomainParticipant instances. More...

List of all members.

Public Attributes
DDS_Long	local_writer_allocation
	The maximum number of local Writers that can be created.
DDS_Long	local_reader_allocation
	The maximum number of local Readers that can be created.
DDS_Long	local_publisher_allocation
	The maximum number of local Publishers that can be created.
DDS_Long	local_subscriber_allocation
	The maximum number of local Subscribers that can be created.
DDS_Long	local_topic_allocation
	The maximum number of topics that can be created.
DDS_Long	local_type_allocation
	The maximum number of local types that can be registered with this DomainParticipant.
DDS_Long	remote_participant_allocation
	The maximum number of remote participants that can be discovered by this DomainParticipant.
DDS_Long	remote_writer_allocation
	The maximum number of remote writers that can be discovered by this DomainParticipant.
DDS_Long	remote_reader_allocation
	The maximum number of remote readers that can be discovered by this DomainParticipant.
DDS_Long	matching_writer_reader_pair_allocation
	The maximum number of matching local writer and remote/local reader pairs.
DDS_Long	max_receive_ports
	Maximum number of addresses that can be listened on.
DDS_Long	max_destination_ports
	Maximum number of unique destination addresses that a participant can reach.

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Detailed Description

<<cert>> Resource limits that apply only to DDSDomainParticipant instances.

This QoS policy is an extension to the DDS standard.

Entity:

DDSDomainParticipant

Properties:

RxO = N/A
Changeable = NO

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Member Data Documentation

DDS_Long DDS_DomainParticipantResourceLimitsQosPolicy::local_writer_allocation

The maximum number of local Writers that can be created.

This resource-limit limits the maximum number of DDSDataWriter entities that can be created with the DDSPublisher::create_datawriter() API within a single DDSDomainParticipant across all DDSPublisher entities.

[default] 1

DDS_Long DDS_DomainParticipantResourceLimitsQosPolicy::local_reader_allocation

The maximum number of local Readers that can be created.

This resource-limit limits the maximum number of DDSDataReader entities that can be created with the DDSSubscriber::create_datareader() API within a single DDSDomainParticipant across all DDSSubscriber entities.

[default] 1

DDS_Long DDS_DomainParticipantResourceLimitsQosPolicy::local_publisher_allocation

The maximum number of local Publishers that can be created.

This resource-limit limits the maximum number of DDSPublisher entities that can be created within a DDSDomainParticipant with the DDSDomainParticipant::create_publisher() API.

[default] 1

DDS_Long DDS_DomainParticipantResourceLimitsQosPolicy::local_subscriber_allocation

The maximum number of local Subscribers that can be created.

This resource-limit limits the maximum number of DDSSubscriber entities that can be created within a DDSDomainParticipant with the DDSDomainParticipant::create_subscriber() API.

[default] 1

DDS_Long DDS_DomainParticipantResourceLimitsQosPolicy::local_topic_allocation

The maximum number of topics that can be created.

This resource-limit limits the maximum number of unique DDSTopic's that can be created within a single DDSDomainParticipant with the DDSDomainParticipant::create_topic() API.

[default] 1

DDS_Long DDS_DomainParticipantResourceLimitsQosPolicy::local_type_allocation

The maximum number of local types that can be registered with this DomainParticipant.

This resource-limit limits the maximum number of unique NDDS_Type_Plugin's that can be registered locally within a single DDSDomainParticipant with the FooTypeSupport::register_type() API.

[default] 1

DDS_Long DDS_DomainParticipantResourceLimitsQosPolicy::remote_participant_allocation

The maximum number of remote participants that can be discovered by this DomainParticipant.

This resource-limit limits the maximum number of DDSDomainParticipant's that can be discovered by a local DDSDomainParticipant.

The DPDE discovery plugin is a first discovered first served basis and the only way to limit discovery is careful use of peer addresses. The DPSE discovery plugin limits the discovery to those that have been asserted based on the DomainParticipant name using DPSEDiscoveryPlugin::RemoteParticipant_assert

[default] 1

DDS_Long DDS_DomainParticipantResourceLimitsQosPolicy::remote_writer_allocation

The maximum number of remote writers that can be discovered by this DomainParticipant.

This resource-limit limits the maximum number of remote DDSDataWriter entities that can be discovered by a local DDSDomainParticipant. Note that a remote DDSDataWriter cannot be discovered until its parent DDSDomainParticipant has been discovered.

[default] 1

DDS_Long DDS_DomainParticipantResourceLimitsQosPolicy::remote_reader_allocation

The maximum number of remote readers that can be discovered by this DomainParticipant.

This resource-limit limits the maximum number of remote DDSDataReader entities that can be discovered by a local DomainParticipant. Note that a remote DDSDataReader cannot be discovered until its parent DDSDomainParticipant has been discovered.

[default] 1

DDS_Long DDS_DomainParticipantResourceLimitsQosPolicy::matching_writer_reader_pair_allocation

The maximum number of matching local writer and remote/local reader pairs.

When RTI Connext Micro discovers DDS entities using a DDS discovery protocol, such as DPSE (Dynamic Participant Static Endpoint) or DPDE (Dynamic Participant Dynamic Endpoint), it matches the discovered entities with the locally created DataReaders and DataWriters. For each match, either a local DataWriter matching a remote DataReader or a local DataReader matching a remote DataWriter, internal state must be managed.

A match, in this context, is defined as being able to receive packets sent from a DDSDataReader to a DDSDataWriter, or from a DDSDataWriter to a DDSDataReader:

• A data-writer needs one resource for each DDSDataReader it matches.
• A data-reader needs one resource for each DDSDataWriter it matches.

This resource-limit limits the maximum number of matches that can be managed. When this resource limit is reached no further matching can occur, even if new DDSDataReader's and DDSDataWriter's are discovered.

A simple rule of thumb is to set this resource limit to:

• (local_reader_allocation + local_writer_allocation) * max_remote_participants.

This assumes that each DDSDataReader and DDSDataWriter matches one DDSDataWriter and DDSDataReader respectively for each discovered participant. However, this may over-allocate resources.

[default] 32

DDS_Long DDS_DomainParticipantResourceLimitsQosPolicy::max_receive_ports

Maximum number of addresses that can be listened on.

RTI Connext Micro listens for discovery data and user data on different transports as specified by the user. This resource-limit limits the maximum number of addresses that can be listened on. As a rule of thumb, this resource limit can be determined as follows: - A user-traffic unicast port counts as 1. - A meta-traffic unicast port counts as 1. - A user-traffic multicast address counts as 1. - A meta-traffic multicast address counts as 1.

Consider the typical case with the UDP transport, using unicast and multicast for discovery data and unicast for user data:

• Discovery data needs two ports.
• User data needs one port.

Thus, this requires 3 resources.

Consider a case with the UDP transport, using unicast and multicast for discovery data and user data: - Discovery data needs two ports. - User data needs two ports.

Thus, this requires 4 resources.

Consider a case with the UDP transport, using unicast and 2 multicast addresses each for discovery data and user data:

• Discovery data needs three ports.
• User data needs three ports.

Thus, this requires 6 resources.

The default value has been set to cover most cases. This resource-limit should only be changed if a lot of interfaces are supported (increase it) or if memory is extremely limited (decrease it).

[default] 8

DDS_Long DDS_DomainParticipantResourceLimitsQosPolicy::max_destination_ports

Maximum number of unique destination addresses that a participant can reach.

RTI Connext Micro maintains a table of destination addresses which it can send to based on information queried from the registered transports. This resource limit is difficult to give a precise rule for how to determine since it is transport dependent. However, as a rule of thumb the following is true: - Each network that can be reached directly by the transport requires 1 resource. - If multicast is supported it counts as 1 resource. - If the transport is the default transport (by default UDP is) it counts as one address

Consider a typical Linux computer with 2 network interfaces, eth0 and lo, with support for multicast:

• 1 for the eth0 network.
• 1 for the lo network.
• 1 for multicast.
• 1 for being the default transport.

This requires 4 resources.

Consider a typical embedded computer with 1 network interfaces, eth0, with no support for multicast:

• 1 for the eth0 network.
• 1 for multicast.
• 1 for being the default transport.

This requires 3 resources.

The default value has been set to cover most cases. This resource-limit should only be changed if a lot of interfaces are supported (increase it) or if memory is extremely limited (decrease it).

[default] 8