Configuring QoS Profiles with XML

APIs related to XML QoS Profiles.

APIs related to XML QoS Profiles.

Loading QoS Profiles from XML Resources

A 'QoS profile' is a group of QoS settings, specified in XML format. By using QoS profiles, you can change QoS settings without recompiling the application.

The Qos profiles are loaded the first time any of the following operations are called:

• DDSDomainParticipantFactory::create_participant
• DDSDomainParticipantFactory::create_participant_with_profile
• DDSDomainParticipantFactory::set_default_participant_qos_with_profile
• DDSDomainParticipantFactory::get_default_participant_qos
• DDSDomainParticipantFactory::set_default_library
• DDSDomainParticipantFactory::set_default_profile
• DDSDomainParticipantFactory::get_participant_qos_from_profile
• DDSDomainParticipantFactory::get_topic_qos_from_profile
• DDSDomainParticipantFactory::get_topic_qos_from_profile_w_topic_name
• DDSDomainParticipantFactory::get_publisher_qos_from_profile
• DDSDomainParticipantFactory::get_subscriber_qos_from_profile
• DDSDomainParticipantFactory::get_datawriter_qos_from_profile
• DDSDomainParticipantFactory::get_datawriter_qos_from_profile_w_topic_name
• DDSDomainParticipantFactory::get_datareader_qos_from_profile
• DDSDomainParticipantFactory::get_datareader_qos_from_profile_w_topic_name
• DDSDomainParticipantFactory::get_qos_profile_libraries
• DDSDomainParticipantFactory::get_qos_profiles
• DDSDomainParticipantFactory::load_profiles

The QoS profiles are reloaded replacing previously loaded profiles when the following operations are called:

• DDSDomainParticipantFactory::set_qos
• DDSDomainParticipantFactory::reload_profiles

The DDSDomainParticipantFactory::unload_profiles operation will free the resources associated with the XML QoS profiles.

There are five ways to configure the XML resources (listed by load order):

• The file NDDS_QOS_PROFILES.xml in $NDDSHOME/resource/xml is loaded if it exists and DDS_ProfileQosPolicy::ignore_resource_profile in DDS_ProfileQosPolicy is set to DDS_BOOLEAN_FALSE (first to be loaded). An example file, NDDS_QOS_PROFILES.example.xml, is available for reference.

• The URL groups separated by semicolons referenced by the enviroment variable NDDS_QOS_PROFILES are loaded if they exist and DDS_ProfileQosPolicy::ignore_environment_profile in DDS_ProfileQosPolicy is set to DDS_BOOLEAN_FALSE.

• The file USER_QOS_PROFILES.xml in the working directory will be loaded if it exists and DDS_ProfileQosPolicy::ignore_user_profile in DDS_ProfileQosPolicy is set to DDS_BOOLEAN_FALSE.

• The URL groups referenced by DDS_ProfileQosPolicy::url_profile in DDS_ProfileQosPolicy will be loaded if specified.

• The sequence of XML strings referenced by DDS_ProfileQosPolicy::string_profile will be loaded if specified (last to be loaded).

The above methods can be combined together.

URL

The location of the XML resources (only files and strings are supported) is specified using a URL (Uniform Resource Locator) format. For example:

File Specification: file:///usr/local/default_dds.xml

String Specification: str://"<dds><qos_library> . . . lt;/qos_library>&lt/dds>"

If the URL schema name is omitted, RTI Connext will assume a file name. For example:

File Specification: /usr/local/default_dds.xml

URL groups

To provide redundancy and fault tolerance, you can specify multiple locations for a single XML document via URL groups. The syntax of a URL group is as follows:

[URL1 | URL2 | URL2 | . . .| URLn]

For example:

[file:///usr/local/default_dds.xml | file:///usr/local/alternative_default_dds.xml]

Only one of the elements in the group will be loaded by RTI Connext, starting from the left.

Brackets are not required for groups with a single URL.

NDDS_QOS_PROFILES environment variable

The environment variable NDDS_QOS_PROFILES contains a list of URL groups separated by ';'

The URL groups referenced by the environment variable are loaded if they exist and DDS_ProfileQosPolicy::ignore_environment_profile is set to DDS_BOOLEAN_FALSE

Built-In QoS Profiles

There are also a number of built-in QoS profiles that can be used without having to load any configurations from outside XML resources. For more information on these built-in profiles see Built-in Qos Profiles.

For more information on XML Configuration, refer to the User's Manual.