[#1228] added DittoHeaderDefinition "live-channel-condition-matched" …

…which will also be written to external headers to find out whether the live channel condition matched

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

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

@@ -278,6 +278,11 @@ public Optional<String> getLiveChannelCondition() {
         return getStringForDefinition(DittoHeaderDefinition.LIVE_CHANNEL_CONDITION);
     }
 
+    @Override
+    public boolean didLiveChannelConditionMatch() {
+        return isExpectedBoolean(DittoHeaderDefinition.LIVE_CHANNEL_CONDITION_MATCHED, Boolean.TRUE);
+    }
+
     @Override
     public Optional<String> getOrigin() {
         return getStringForDefinition(DittoHeaderDefinition.ORIGIN);

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

@@ -395,18 +395,36 @@ public enum DittoHeaderDefinition implements HeaderDefinition {
             HeaderValueValidators.getNoOpValidator()),
 
     /**
-     * Header definition to identify a request with a conditional channel.
-     * The condition is defined via a RQL expressions, which is evaluated in the things service. If the condition is
+     * Header definition containing a condition which, when evaluating to {@code true}, shall switch the
+     * {@link #CHANNEL} to use to the {@code "live"} channel.
+     * The condition is defined via a RQL expressions, which is evaluated in the things persistence. If the condition is
      * evaluated to 'true', then the live-channel is used instead of the regular twin-channel.
      *
      * <p>
      * Key {@code "live-channel-condition"}, Java type: {@link String}.
      * </p>
      *
-     * @since 2.2.0
+     * @since 2.3.0
      */
     LIVE_CHANNEL_CONDITION("live-channel-condition", String.class, true, false,
-            HeaderValueValidators.getNoOpValidator());
+            HeaderValueValidators.getNoOpValidator()),
+
+    /**
+     * Header containing the result of the {@link #LIVE_CHANNEL_CONDITION} evaluated in the things persistence.
+     * If this contains {@code true}, the {@code "live"} channel shall be used in order to handle a processed command.
+     * If this header is missing or contains value {@code false}, the live channel shall not be used and the twin
+     * response this header is transported with shall be returned instead.
+     *
+     * <p>
+     * Key {@code "live-channel-condition-matched"}, Java type: {@link Boolean}.
+     * </p>
+     *
+     * @since 2.3.0
+     */
+    LIVE_CHANNEL_CONDITION_MATCHED("live-channel-condition-matched", Boolean.class,
+            false, true, HeaderValueValidators.getBooleanValidator())
+
+    ;
 
     /**
      * Map to speed up lookup of header definition by key.

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

@@ -216,10 +216,19 @@ static DittoHeadersBuilder newBuilder(final JsonObject jsonObject) {
      * Returns the channel condition, if the live-channel shall be used for the request.
      *
      * @return the condition contained in the Condition header.
-     * @since 2.2.0
+     * @since 2.3.0
      */
     Optional<String> getLiveChannelCondition();
 
+    /**
+     * Returns whether the live channel condition passed to the things persistence via the
+     * {@link #getLiveChannelCondition()} header did match the persisted state of a thing or not.
+     *
+     * @return whether the live channel condition passed to the things persistence matched or not.
+     * @since 2.3.0
+     */
+    boolean didLiveChannelConditionMatch();
+
     /**
      * Returns the id of the originating session (e.g. WebSocket, AMQP, ...)
      *

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

@@ -110,6 +110,7 @@ public final class ImmutableDittoHeadersTest {
     private static final boolean KNOWN_IS_SUDO = true;
     private static final String KNOWN_CONDITION = "eq(attributes/value)";
     private static final String KNOWN_LIVE_CHANNEL_CONDITION = "eq(attributes/value,\"livePolling\")";
+    private static final boolean KNOWN_LIVE_CHANNEL_CONDITION_MATCHED = true;
     private static final String KNOWN_TRACEPARENT = "00-dfca0d990402884d22e909a87ac677ec-94fc4da95e842f96-01";
     private static final String KNOWN_TRACESTATE = "eclipse=ditto";
     private static final boolean KNOWN_DITTO_RETRIEVE_DELETED = true;
@@ -178,6 +179,8 @@ public void settingAllKnownHeadersWorksAsExpected() {
                 .putHeader(DittoHeaderDefinition.W3C_TRACESTATE.getKey(), KNOWN_TRACESTATE)
                 .condition(KNOWN_CONDITION)
                 .liveChannelCondition(KNOWN_LIVE_CHANNEL_CONDITION)
+                .putHeader(DittoHeaderDefinition.LIVE_CHANNEL_CONDITION_MATCHED.getKey(),
+                        String.valueOf(KNOWN_LIVE_CHANNEL_CONDITION_MATCHED))
                 .build();
 
         assertThat(underTest).isEqualTo(expectedHeaderMap);
@@ -334,6 +337,31 @@ public void isSudoIsTrueWhenTrue() {
         assertThat(underTest.isSudo()).isTrue();
     }
 
+    @Test
+    public void didLiveChannelConditionMatchIsFalseOnMissingHeader() {
+        final DittoHeaders underTest = DittoHeaders.empty();
+
+        assertThat(underTest.didLiveChannelConditionMatch()).isFalse();
+    }
+
+    @Test
+    public void didLiveChannelConditionMatchIsFalseWhenFalse() {
+        final DittoHeaders underTest = DittoHeaders.newBuilder()
+                .putHeader(DittoHeaderDefinition.LIVE_CHANNEL_CONDITION_MATCHED.getKey(), "false")
+                .build();
+
+        assertThat(underTest.didLiveChannelConditionMatch()).isFalse();
+    }
+
+    @Test
+    public void didLiveChannelConditionMatchIsTrueWhenTrue() {
+        final DittoHeaders underTest = DittoHeaders.newBuilder()
+                .putHeader(DittoHeaderDefinition.LIVE_CHANNEL_CONDITION_MATCHED.getKey(), "true")
+                .build();
+
+        assertThat(underTest.didLiveChannelConditionMatch()).isTrue();
+    }
+
     @Test
     public void liveChannelConditionNotEmptyWhenSet() {
         final String testValue = "some-condition";
@@ -453,6 +481,8 @@ public void toJsonReturnsExpected() {
                 .set(DittoHeaderDefinition.W3C_TRACESTATE.getKey(), KNOWN_TRACESTATE)
                 .set(DittoHeaderDefinition.CONDITION.getKey(), KNOWN_CONDITION)
                 .set(DittoHeaderDefinition.LIVE_CHANNEL_CONDITION.getKey(), KNOWN_LIVE_CHANNEL_CONDITION)
+                .set(DittoHeaderDefinition.LIVE_CHANNEL_CONDITION_MATCHED.getKey(),
+                        KNOWN_LIVE_CHANNEL_CONDITION_MATCHED)
                 .build();
 
         final Map<String, String> allKnownHeaders = createMapContainingAllKnownHeaders();
@@ -684,6 +714,8 @@ private static Map<String, String> createMapContainingAllKnownHeaders() {
         result.put(DittoHeaderDefinition.W3C_TRACESTATE.getKey(), KNOWN_TRACESTATE);
         result.put(DittoHeaderDefinition.CONDITION.getKey(), KNOWN_CONDITION);
         result.put(DittoHeaderDefinition.LIVE_CHANNEL_CONDITION.getKey(), KNOWN_LIVE_CHANNEL_CONDITION);
+        result.put(DittoHeaderDefinition.LIVE_CHANNEL_CONDITION_MATCHED.getKey(),
+                String.valueOf(KNOWN_LIVE_CHANNEL_CONDITION_MATCHED));
 
         return result;
     }