31. Configuring Persistence Service

To use Persistence Service:

1. Modify your Connext DDS applications.
• The 7.5.9 DURABILITY QosPolicy controls whether or not, and how, published DDS samples are stored by Persistence Service for delivery to late-joining DataReaders. See 13.5 Data Durability.
• For each DataWriter whose data must be stored, set the Durability QosPolicy’s kind to DDS_PERSISTENT_DURABILITY_QOS or DDS_TRANSIENT_DURABILITY_QOS.
• For each DataReader that needs to receive stored data, set the Durability QosPolicy’s kind to DDS_PERSISTENT_DURABILITY_QOS or DDS_TRANSIENT_DURABILITY_QOS.
• Optionally, modify the 7.5.10 DURABILITY SERVICE QosPolicy, which can be used to configure Persistence Service.

By default, the History and ResourceLimits QosPolicies for a Persistence Service DataReader (PRSTDataReader) and Persistence Service DataWriter (PRSTDataWriter) with topic 'A' will be configured using the values specified in the XML file (unless you use the tag <use_durability_service> in the persistence group definition, see 31.8 Creating Persistence Groups). Setting the <use_durability_service> tag to true will cause the History and ResourceLimits QosPolicies for a PRSTDataReader and PRSTDataWriter to be configured using the 7.5.10 DURABILITY SERVICE QosPolicy of the first-discovered DataWriter publishing 'A'. (For more information on the PRSTDataReader and PRSTDataWriter, see 13.5.1 RTI Persistence Service.)

2. Create a configuration file or edit an existing file, as described in 31.2 XML Configuration File.
3. Start Persistence Service with your configuration file, as described in 32.1 Starting Persistence Service. You can start it on either application’s node, or even an entirely different node (provided that node is included in one of the applications’ NDDS_DISCOVERY_PEERS lists).

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