Refs #21538: Specify new PERSISTENT behavior and TRANSIENT with no pe…

…rsistence guid

Signed-off-by: Mario Dominguez <[email protected]>

docs/fastdds/dds_layer/core/policy/standardQosPolicies.rst

@@ -211,8 +211,8 @@ There are four possible values (see |DurabilityQosPolicyKind-api|):
 * |TRANSIENT_LOCAL_DURABILITY_QOS-api|: When a new DataReader joins, its History is filled with past samples.
 * |TRANSIENT_DURABILITY_QOS-api|: When a new DataReader joins, its History is filled with past samples, which are stored
   on persistent storage (see :ref:`persistence_service`).
-* |PERSISTENT_DURABILITY_QOS-api|: (`Not Implemented`): All the samples are stored on a permanent storage, so that they
-  can outlive a system session.
+* |PERSISTENT_DURABILITY_QOS-api|: (`Not Implemented`, currently behaves as |TRANSIENT_DURABILITY_QOS-api|):
+  All the samples are stored on a permanent storage, so that they can outlive a system session.
 
 .. _durability_compatibilityrule:
 

docs/fastdds/persistence/persistence.rst

@@ -40,7 +40,7 @@ The configuration of the persistence service is accomplished by setting of the a
 or DataReader) |PropertyPolicyQos|.
 
 * For the :ref:`persistence_service` to have any effect, the |DurabilityQosPolicyKind-api| needs to be set to
-  |TRANSIENT_DURABILITY_QOS-api|.
+  |TRANSIENT_DURABILITY_QOS-api| or |PERSISTENT_DURABILITY_QOS-api| (which behaves as |TRANSIENT_DURABILITY_QOS-api|).
 
 * A persistence identifier (|Guid_t-api|) must be set for the entity using the property ``dds.persistence.guid``.
   This identifier is used to load the appropriate data from the database, and also to synchronize DataWriter and
@@ -56,9 +56,16 @@ or DataReader) |PropertyPolicyQos|.
   For selecting an appropriate GUID for the DataReader and DataWriter, please refer to
   `RTPS standard <https://www.omg.org/spec/DDSI-RTPS/2.2/PDF>`_ (section *9.3.1 The Globally Unique Identifier (GUID)*).
 
+  If no ``dds.persistence.guid`` is specified, the durability will fallback to |TRANSIENT_LOCAL_DURABILITY_QOS-api|.
+
 * A persistence plugin must be configured for managing the database using property ``dds.persistence.plugin`` (see
   :ref:`persistence_sqlite3_builtin_plugin`):
 
+.. note::
+
+    If the |DurabilityQosPolicyKind-api| is set to |TRANSIENT_DURABILITY_QOS-api| or |PERSISTENT_DURABILITY_QOS-api|
+    and no ``dds.persistence.guid`` is specified, |TRANSIENT_LOCAL_DURABILITY_QOS-api| will be used.
+
 
 .. _persistence_sqlite3_builtin_plugin: