Add yang-data-api API evolution guidance

[yangtools.git] / yang / yang-data-api / src / main / java / org / opendaylight / yangtools / yang / data / api / schema / NormalizedNode.java

diff --git a/yang/yang-data-api/src/main/java/org/opendaylight/yangtools/yang/data/api/schema/NormalizedNode.java b/yang/yang-data-api/src/main/java/org/opendaylight/yangtools/yang/data/api/schema/NormalizedNode.java
index 72688525ea028877f3539e592c99602bad7e7568..31a385ce4b5009d91810c09190d1f7da301ecf49 100644 (file)
--- a/yang/yang-data-api/src/main/java/org/opendaylight/yangtools/yang/data/api/schema/NormalizedNode.java
+++ b/yang/yang-data-api/src/main/java/org/opendaylight/yangtools/yang/data/api/schema/NormalizedNode.java
@@ -22,6 +22,28 @@ import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.PathArgum
  * @param <K> Local identifier of node
  * @param <V> Value of node
  */
+/*
+ * FIXME: 3.0.0: NormalizedNode represents the perfectly-compliant view of the data, as evaluated by an implementation,
+ *               which is currently singular, with respect of its interpretation of a SchemaContext. This includes
+ *               leaf values, which are required to hold normalized representation for a particular implementation,
+ *               which may be affected by its understanding of any YANG extensions present -- such as optional type
+ *               handling hints and bindings.
+ *
+ *               Implementations (i.e. the reference implementation and parsers) will need to start using
+ *               yang.common.Uint8 and friends and, if possible, express data validation in terms
+ *               of yang.common.CanonicalValue and yang.common.CanonicalValueValidator.
+ *
+ *               This notably means that to efficiently implement any sort of lenient parsing, we need a separate
+ *               concept which contains an unverified, potentially non-conformant data tree, which the consumer needs
+ *               to check/fixup if it wishes to use it as a NormalizedNode. Such a concept should be called
+ *               "UnverifiedData".
+ */
+/*
+ * FIXME: 4.0.0: Once we have UnverifiedData, we should really rename this to "NormalizedData" or similar to unload
+ *               some "Node" ambiguity. "Node" should be a generic term reserved for a particular domain -- hence 'node'
+ *               can be used to refer to either a 'schema node' in context of yang.model.api, or to
+ *               a 'normalized data node' in context of yang.data.api.
+ */
 public interface NormalizedNode<K extends PathArgument, V> extends Identifiable<K> {
     /**
      * QName of the node as defined in YANG schema.