DDS_GroupDataQosPolicy Struct Reference
[GROUP_DATA]

Attaches a buffer of opaque data that is distributed by means of Built-in Topics during discovery. More...

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Public Attributes
struct DDS_OctetSeq	value
	a sequence of octets

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Detailed Description

Attaches a buffer of opaque data that is distributed by means of Built-in Topics during discovery.

Entity:

DDSPublisher, DDSSubscriber

Properties:

RxO = NO
Changeable = YES

See also:

DDSDomainParticipant::get_builtin_subscriber

Usage

The additional information is attached to a DDSPublisher or DDSSubscriber. This extra data is not used by RTI Data Distribution Service itself. When a remote application discovers the DDSPublisher or DDSSubscriber, it can access that information and use it for its own purposes.

Use cases for this QoS policy, as well as the DDS_TopicDataQosPolicy and DDS_UserDataQosPolicy, are often application-to-application identification, authentication, authorization, and encryption purposes. For example, applications can use Group or User Data to send security certificates to each other for RSA-type security.

In combination with DDSDataReaderListener, DDSDataWriterListener and operations such as DDSDomainParticipant::ignore_publication and DDSDomainParticipant::ignore_subscription, this QoS policy can help an application to define and enforce its own security policies. For example, an application can implement matching policies similar to those of the DDS_PartitionQosPolicy, except the decision can be made based on an application-defined policy.

The use of this QoS is not limited to security; it offers a simple, yet flexible extensibility mechanism.

Important: RTI Data Distribution Service stores the data placed in this policy in pre-allocated pools. It is therefore necessary to configure RTI Data Distribution Service with the maximum size of the data that will be stored in policies of this type. This size is configured with DDS_DomainParticipantResourceLimitsQosPolicy::publisher_group_data_max_length and DDS_DomainParticipantResourceLimitsQosPolicy::subscriber_group_data_max_length.

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Member Data Documentation

struct DDS_OctetSeq DDS_GroupDataQosPolicy::value [read]

a sequence of octets

[default] Empty (zero-sized)

[range] Octet sequence of length [0,max_length]