#96 implement partial read acess events emitting

Author: hu-ahmed

base/model/src/main/java/org/eclipse/ditto/base/model/headers/DittoHeaderDefinition.java

@@ -623,6 +623,38 @@ public enum DittoHeaderDefinition implements HeaderDefinition {
             false,
             HeaderValueValidators.getJsonObjectValidator()),
 
+    /**
+     * Internal header containing partial access paths for subjects with partial READ permissions.
+     * Used to enable partial change notifications for subjects with restricted READ permissions.
+     * <p>
+     * Key: {@code "ditto-partial-access-paths"}, Java type: {@link JsonObject}.
+     * Format (indexed):
+     * </p>
+     * <pre>{@code
+     * {
+     *   "subjects": [
+     *     "foo-idp:groupA",
+     *     "foo-idp:user1"
+     *   ],
+     *   "paths": {
+     *     "attributes/location": [0],
+     *     "features/A/properties/status": [0, 1]
+     *   }
+     * }
+     * }</pre>
+     * <p>
+     * Each path maps to integer indices referring to entries in the {@code subjects} array.
+     * This indexed format reduces header size when multiple subjects share the same paths.
+     * </p>
+     *
+     * @since 3.9.0
+     */
+    PARTIAL_ACCESS_PATHS("ditto-partial-access-paths",
+            JsonObject.class,
+            false,
+            false,
+            HeaderValueValidators.getJsonObjectValidator()),
+
     /**
      * Internal header containing pre-defined {@code extraFields} as JSON object sent along for emitted thing event.
      *

base/model/src/test/java/org/eclipse/ditto/base/model/headers/ImmutableDittoHeadersTest.java

@@ -235,6 +235,8 @@ public void settingAllKnownHeadersWorksAsExpected() {
                         KNOWN_PRE_DEFINED_EXTRA_FIELDS_READ_GRANT_OBJECT.formatAsString())
                 .putHeader(DittoHeaderDefinition.PRE_DEFINED_EXTRA_FIELDS_OBJECT.getKey(),
                         KNOWN_PRE_DEFINED_EXTRA_FIELDS_OBJECT.formatAsString())
+                .putHeader(DittoHeaderDefinition.PARTIAL_ACCESS_PATHS.getKey(),
+                        "{\"subjects\":[\"test:subject\"],\"paths\":{\"attributes\":[0],\"features/fluxCompensator/properties/baz\":[0]}}")
                 .putHeader(DittoHeaderDefinition.EXTERNAL_DRY_RUN.getKey(), String.valueOf(KNOWN_DITTO_EXTERNAL_DRY_RUN))
                 .putHeader(DittoHeaderDefinition.DIVERT_RESPONSE_TO_CONNECTION.getKey(), KNOWN_DITTO_DIVERT_RESPONSE_TO)
                 .putHeader(DittoHeaderDefinition.DIVERTED_RESPONSE_FROM_CONNECTION.getKey(), KNOWN_DITTO_DIVERTED_RESPONSE_FROM)
@@ -574,6 +576,20 @@ public void toJsonReturnsExpected() {
                         KNOWN_PRE_DEFINED_EXTRA_FIELDS_READ_GRANT_OBJECT)
                 .set(DittoHeaderDefinition.PRE_DEFINED_EXTRA_FIELDS_OBJECT.getKey(),
                         KNOWN_PRE_DEFINED_EXTRA_FIELDS_OBJECT)
+                .set(DittoHeaderDefinition.PARTIAL_ACCESS_PATHS.getKey(),
+                        JsonObject.newBuilder()
+                                .set("subjects", JsonArray.newBuilder()
+                                        .add("test:subject")
+                                        .build())
+                                .set("paths", JsonObject.newBuilder()
+                                        .set("attributes", JsonArray.newBuilder()
+                                                .add(0)
+                                                .build())
+                                        .set("features/fluxCompensator/properties/baz", JsonArray.newBuilder()
+                                                .add(0)
+                                                .build())
+                                        .build())
+                                .build())
                 .set(DittoHeaderDefinition.EXTERNAL_DRY_RUN.getKey(), KNOWN_DITTO_EXTERNAL_DRY_RUN)
                 .set(DittoHeaderDefinition.PUT_METADATA.getKey(), KNOWN_METADATA_HEADERS.toJson())
                 .set(DittoHeaderDefinition.GET_METADATA.getKey(), KNOWN_DITTO_GET_METADATA)
@@ -829,6 +845,8 @@ private static Map<String, String> createMapContainingAllKnownHeaders() {
                 KNOWN_PRE_DEFINED_EXTRA_FIELDS_READ_GRANT_OBJECT.formatAsString());
         result.put(DittoHeaderDefinition.PRE_DEFINED_EXTRA_FIELDS_OBJECT.getKey(),
                 KNOWN_PRE_DEFINED_EXTRA_FIELDS_OBJECT.formatAsString());
+        result.put(DittoHeaderDefinition.PARTIAL_ACCESS_PATHS.getKey(),
+                "{\"subjects\":[\"test:subject\"],\"paths\":{\"attributes\":[0],\"features/fluxCompensator/properties/baz\":[0]}}");
         result.put(DittoHeaderDefinition.EXTERNAL_DRY_RUN.getKey(),
                 String.valueOf(KNOWN_DITTO_EXTERNAL_DRY_RUN));
         result.put(DittoHeaderDefinition.DIVERT_RESPONSE_TO_CONNECTION.getKey(), KNOWN_DITTO_DIVERT_RESPONSE_TO);