Require plain json object as metadata

docs/api/appending-events.md

@@ -256,18 +256,17 @@ This feature is only available in KurrentDB 25.1 and later.
 You can append events to multiple streams in a single atomic operation. Either all streams are updated, or the entire operation fails.
 
 ::: warning
-Currently, metadata must be valid JSON. Binary metadata will not be supported in
-this version. This limitation ensures compatibility with KurrentDB's metadata
-handling and will be removed in the next major release.
+Metadata must be a valid JSON object, using string keys and string values only.
+Binary metadata is not supported in this version to maintain compatibility with
+KurrentDB's metadata handling. This restriction will be lifted in the next major
+release.
 :::
 
 ```java
 JsonMapper mapper = new JsonMapper();
 
 Map<String, Object> metadata = new HashMap<>();
-metadata.put("timestamp", Instant.now().toString());
-        metadata.put("source", "OrderProcessingSystem");
-metadata.put("version", 1.0);
+metadata.put("source", "OrderProcessingSystem");
 
 byte[] metadataBytes = mapper.writeValueAsBytes(metadata);
 

src/main/java/io/kurrent/dbclient/DynamicValueMapper.java

@@ -2,14 +2,8 @@
 
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.json.JsonMapper;
-import com.google.protobuf.ByteString;
-import com.google.protobuf.Timestamp;
-import com.google.protobuf.Duration;
 import com.google.protobuf.Value;
 
-import java.time.Instant;
-import java.time.LocalDateTime;
-import java.time.ZonedDateTime;
 import java.util.Collections;
 import java.util.Map;
 import java.util.stream.Collectors;
@@ -25,6 +19,7 @@ public class DynamicValueMapper {
      *
      * @param jsonMetadata the source metadata as JSON bytes
      * @return a map with DynamicValue objects
+     * @throws IllegalArgumentException if any metadata value is not a string
      */
     public static Map<String, Value> mapJsonToValueMap(byte[] jsonMetadata) {
         if (jsonMetadata == null || jsonMetadata.length == 0)
@@ -35,7 +30,7 @@ public static Map<String, Value> mapJsonToValueMap(byte[] jsonMetadata) {
             });
             return mapToValueMap(metadata);
         } catch (Exception e) {
-            return Collections.emptyMap();
+            throw new IllegalArgumentException(e);
         }
     }
 
@@ -44,85 +39,26 @@ public static Map<String, Value> mapJsonToValueMap(byte[] jsonMetadata) {
      *
      * @param metadata the source metadata map
      * @return a map with DynamicValue objects
+     * @throws IllegalArgumentException if any metadata value is not a string
      */
-    public static Map<String, Value> mapToValueMap(Map<String, Object> metadata) {
+    public static Map<String, Value> mapToValueMap(Map<String, ?> metadata) {
         if (metadata == null) {
             return Collections.emptyMap();
         }
 
-        return metadata.entrySet().stream()
-                .collect(Collectors.toMap(
-                        Map.Entry::getKey,
-                        entry -> mapToValue(entry.getValue())
-                ));
-    }
-
-    /**
-     * Converts a Java object to a DynamicValue protobuf message.
-     *
-     * @param source the source object
-     * @return the corresponding DynamicValue
-     */
-    public static Value mapToValue(Object source) {
-        if (source == null) {
-            return Value.newBuilder()
-                    .setNullValue(com.google.protobuf.NullValue.NULL_VALUE)
-                    .build();
+        for (Map.Entry<String, ?> entry : metadata.entrySet()) {
+            if (entry.getValue() != null && !(entry.getValue() instanceof String)) {
+                throw new IllegalArgumentException(
+                        String.format("Metadata value for key '%s' must be a string, but was %s",
+                                entry.getKey(),
+                                entry.getValue().getClass().getSimpleName())
+                );
+            }
         }
 
         Value.Builder builder = Value.newBuilder();
 
-        if (source instanceof String) {
-            return builder.setStringValue((String) source).build();
-        } else if (source instanceof Boolean) {
-            return builder.setBoolValue((Boolean) source).build();
-        } else if (source instanceof Integer) {
-            return builder.setNumberValue((Integer) source).build();
-        } else if (source instanceof Long) {
-            return builder.setNumberValue((Long) source).build();
-        } else if (source instanceof Float) {
-            return builder.setNumberValue((Float) source).build();
-        } else if (source instanceof Double) {
-            return builder.setNumberValue((Double) source).build();
-        } else if (source instanceof Instant) {
-            Instant instant = (Instant) source;
-            return builder.setStringValue(
-                    Timestamp.newBuilder()
-                            .setSeconds(instant.getEpochSecond())
-                            .setNanos(instant.getNano())
-                            .build().toString()
-            ).build();
-        } else if (source instanceof LocalDateTime) {
-            LocalDateTime localDateTime = (LocalDateTime) source;
-            Instant instant = localDateTime.atZone(java.time.ZoneOffset.UTC).toInstant();
-            return builder.setStringValue(
-                    Timestamp.newBuilder()
-                            .setSeconds(instant.getEpochSecond())
-                            .setNanos(instant.getNano())
-                            .build().toString()
-            ).build();
-        } else if (source instanceof ZonedDateTime) {
-            ZonedDateTime zonedDateTime = (ZonedDateTime) source;
-            Instant instant = zonedDateTime.toInstant();
-            return builder.setStringValue(
-                    Timestamp.newBuilder()
-                            .setSeconds(instant.getEpochSecond())
-                            .setNanos(instant.getNano())
-                            .build().toString()
-            ).build();
-        } else if (source instanceof java.time.Duration) {
-            java.time.Duration duration = (java.time.Duration) source;
-            return builder.setStringValue(
-                    Duration.newBuilder()
-                            .setSeconds(duration.getSeconds())
-                            .setNanos(duration.getNano())
-                            .build().toString()
-            ).build();
-        } else if (source instanceof byte[]) {
-            return builder.setStringValue(ByteString.copyFrom((byte[]) source).toStringUtf8()).build();
-        } else {
-            // For any other type, convert to string
-            return builder.setStringValue(source.toString()).build();
-        }
+        return metadata.entrySet().stream()
+                .collect(Collectors.toMap(Map.Entry::getKey, entry -> builder.setStringValue((String) entry.getValue()).build()));
     }
 }

src/main/java/io/kurrent/dbclient/MultiStreamAppend.java

@@ -2,7 +2,6 @@
 
 import com.google.protobuf.ByteString;
 import com.google.protobuf.Value;
-import com.google.rpc.ErrorInfo;
 import io.grpc.StatusRuntimeException;
 import io.grpc.stub.StreamObserver;
 import io.grpc.stub.ClientResponseObserver;

src/test/java/io/kurrent/dbclient/MultiStreamAppendTests.java

@@ -5,7 +5,6 @@
 import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
-import java.time.Instant;
 import java.util.*;
 import java.util.concurrent.ExecutionException;
 
@@ -36,7 +35,7 @@ public static void cleanup() {
     }
 
     @Test
-    public void testMultiStreamAppend() throws ExecutionException, InterruptedException, IOException {
+    public void testBadEventMetadata() throws ExecutionException, InterruptedException, IOException {
         KurrentDBClient client = getDefaultClient();
 
         Optional<ServerVersion> version = client.getServerVersion().get();
@@ -48,16 +47,50 @@ public void testMultiStreamAppend() throws ExecutionException, InterruptedExcept
 
         // Arrange
         String streamName1 = generateName();
-        String streamName2 = generateName();
 
         Map<String, Object> metadata = new HashMap<>();
         metadata.put("stringProperty", "hello world");
         metadata.put("intProperty", 42);
-        metadata.put("longProperty", 9876543210L);
-        metadata.put("booleanProperty", true);
-        metadata.put("doubleProperty", 3.14159);
-        metadata.put("nullProperty", null);
-        metadata.put("timestampProperty", Instant.now().toString());
+
+        byte[] metadataBytes = mapper.writeValueAsBytes(metadata);
+
+        EventData event1 = EventData.builderAsJson("event-a", "{\"data\":\"test1\"}".getBytes())
+                .metadataAsBytes(metadataBytes)
+                .build();
+
+        List<EventData> events1 = Collections.singletonList(event1);
+
+        List<AppendStreamRequest> requests = Collections.singletonList(
+                new AppendStreamRequest(streamName1, events1.iterator(), StreamState.noStream())
+        );
+
+        // Act & Assert
+        Assertions.assertThrows(IllegalArgumentException.class, () -> {
+            try {
+                client.multiStreamAppend(requests.iterator()).get();
+            } catch (ExecutionException e) {
+                throw e.getCause();
+            }
+        });
+    }
+
+    @Test
+    public void testMultiStreamAppend() throws ExecutionException, InterruptedException, IOException {
+        KurrentDBClient client = getDefaultClient();
+
+        Optional<ServerVersion> version = client.getServerVersion().get();
+
+        Assumptions.assumeTrue(
+                version.isPresent() && version.get().isGreaterOrEqualThan(25, 0),
+                "Multi-stream append is not supported server versions below 25.0.0"
+        );
+
+        // Arrange
+        String streamName1 = generateName();
+        String streamName2 = generateName();
+
+        Map<String, String> metadata = new HashMap<>();
+        metadata.put("stringProperty", "hello world");
 
         byte[] metadataBytes = mapper.writeValueAsBytes(metadata);
 
@@ -94,12 +127,6 @@ public void testMultiStreamAppend() throws ExecutionException, InterruptedExcept
 
         Map deserializedMetadata = mapper.readValue(readMetadata, Map.class);
         Assertions.assertEquals(metadata.get("stringProperty"), deserializedMetadata.get("stringProperty"));
-        Assertions.assertEquals(metadata.get("intProperty"), deserializedMetadata.get("intProperty"));
-        Assertions.assertEquals(metadata.get("longProperty"), ((Number) deserializedMetadata.get("longProperty")).longValue());
-        Assertions.assertEquals(metadata.get("booleanProperty"), deserializedMetadata.get("booleanProperty"));
-        Assertions.assertEquals((Double) metadata.get("doubleProperty"), ((Number) deserializedMetadata.get("doubleProperty")).doubleValue(), 0.00001);
-        Assertions.assertEquals(metadata.get("timestampProperty"), deserializedMetadata.get("timestampProperty"));
-        Assertions.assertNull(deserializedMetadata.get("nullProperty"));
 
         List<ResolvedEvent> readEvents2 = client.readStream(streamName2, ReadStreamOptions.get()).get().getEvents();
         Assertions.assertEquals(1, readEvents2.size());

src/test/java/io/kurrent/dbclient/telemetry/StreamsTracingInstrumentationTests.java

@@ -344,7 +344,7 @@ default void testMultiStreamAppendIsInstrumentedWithTracingAsExpected() throws T
     }
 
     @Test
-    default void testMultiStreamAppendIsInstrumentedWithFailures() throws Throwable {
+    default void testMultiStreamAppendIsInstrumentedWithErrors() throws Throwable {
         KurrentDBClient client = getDefaultClient();
 
         Optional<ServerVersion> version = client.getServerVersion().get();
@@ -377,20 +377,22 @@ default void testMultiStreamAppendIsInstrumentedWithFailures() throws Throwable
                 StreamState.streamExists()
         );
 
-        MultiStreamAppendResponse result = client.multiStreamAppend(
-                Arrays.asList(request1, request2).iterator()
-        ).get();
+        WrongExpectedVersionException actualException = null;
+        try {
+            MultiStreamAppendResponse result = client.multiStreamAppend(
+                    Arrays.asList(request1, request2).iterator()
+            ).get();
+        } catch (ExecutionException e) {
+            if (e.getCause() instanceof WrongExpectedVersionException)
+                actualException = (WrongExpectedVersionException) e.getCause();
+        }
 
-        Assertions.assertNotNull(result);
-        Assertions.assertFalse(result.getResults().isEmpty());
-        Assertions.assertTrue(result.getPosition() > 0);
+        // Ensure WrongExpectedVersionException was thrown.
+        Assertions.assertNotNull(actualException);
 
         List<ReadableSpan> spans = getSpansForOperation(ClientTelemetryConstants.Operations.MULTI_APPEND);
         Assertions.assertEquals(1, spans.size());
 
-        ReadableSpan span = spans.get(0);
-
-        Assertions.assertEquals(StatusCode.ERROR, span.toSpanData().getStatus().getStatusCode());
-        Assertions.assertEquals(SpanKind.CLIENT, span.getKind());
+        assertErroneousSpanHasExpectedAttributes(spans.get(0), actualException);
     }
 }