[backport camel-4.18.x] CAMEL-25694: camel-milo - fix write/call service failures being reported as success

components/camel-milo/src/main/java/org/apache/camel/component/milo/client/internal/SubscriptionManager.java

@@ -957,13 +957,12 @@ public CompletableFuture<CallMethodResult> call(
                 return newNotConnectedResult();
             }
 
-            return this.connected.call(nodeId, methodId, inputArguments).handleAsync((status, e) -> {
+            return this.connected.call(nodeId, methodId, inputArguments).whenCompleteAsync((status, e) -> {
                 // handle outside the lock, running using
-                // handleAsync
+                // whenCompleteAsync (preserves the original exceptional completion)
                 if (e != null) {
                     handleConnectionFailure(e);
                 }
-                return null;
             }, this.executor);
         }
     }
@@ -974,13 +973,12 @@ public CompletableFuture<?> write(final ExpandedNodeId nodeId, final DataValue v
                 return newNotConnectedResult();
             }
 
-            return this.connected.write(nodeId, value).handleAsync((status, e) -> {
+            return this.connected.write(nodeId, value).whenCompleteAsync((status, e) -> {
                 // handle outside the lock, running using
-                // handleAsync
+                // whenCompleteAsync (preserves the original exceptional completion)
                 if (e != null) {
                     handleConnectionFailure(e);
                 }
-                return status;
             }, this.executor);
         }
     }
@@ -991,13 +989,12 @@ public CompletableFuture<?> readValues(final List<ExpandedNodeId> nodeIds) {
                 return newNotConnectedResult();
             }
 
-            return this.connected.readValues(nodeIds).handleAsync((nodes, e) -> {
+            return this.connected.readValues(nodeIds).whenCompleteAsync((nodes, e) -> {
                 // handle outside the lock, running using
-                // handleAsync
+                // whenCompleteAsync (preserves the original exceptional completion)
                 if (e != null) {
                     handleConnectionFailure(e);
                 }
-                return nodes;
             }, this.executor);
         }
     }
@@ -1012,13 +1009,12 @@ public CompletableFuture<Map<ExpandedNodeId, BrowseResult>> browse(
 
             return this.connected.browse(expandedNodeIds, direction, nodeClasses, 1, maxDepth,
                     null != filter ? Pattern.compile(filter) : null, includeSubTypes, maxNodesPerRequest)
-                    .handleAsync((browseResult, e) -> {
+                    .whenCompleteAsync((browseResult, e) -> {
                         // handle outside the lock, running using
-                        // handleAsync
+                        // whenCompleteAsync (preserves the original exceptional completion)
                         if (e != null) {
                             handleConnectionFailure(e);
                         }
-                        return browseResult;
                     }, this.executor);
         }
     }

components/camel-milo/src/test/java/org/apache/camel/component/milo/call/CallClientTest.java

@@ -37,6 +37,7 @@
 import org.eclipse.milo.opcua.stack.core.transport.TransportProfile;
 import org.eclipse.milo.opcua.stack.core.types.builtin.LocalizedText;
 import org.eclipse.milo.opcua.stack.core.types.enumerated.MessageSecurityMode;
+import org.eclipse.milo.opcua.stack.core.types.structured.CallMethodResult;
 import org.eclipse.milo.opcua.stack.core.types.structured.UserTokenPolicy;
 import org.eclipse.milo.opcua.stack.transport.server.tcp.OpcTcpServerTransport;
 import org.eclipse.milo.opcua.stack.transport.server.tcp.OpcTcpServerTransportConfig;
@@ -48,7 +49,9 @@
 
 import static org.apache.camel.component.milo.NodeIds.nodeValue;
 import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * Unit tests for calling from the client side
@@ -194,6 +197,18 @@ private EndpointConfig buildTcpEndpoint(EndpointConfig.Builder base) {
                 .build();
     }
 
+    @Test
+    public void testAwaitedCallReturnsResult() {
+        // Before CAMEL-25694, the call() handleAsync unconditionally returned null even on success,
+        // so an awaited call always left the exchange body null. Now the body is the CallMethodResult.
+        final CallMethodResult result = this.producer1.requestBodyAndHeader(
+                DIRECT_START_1, "foo", "CamelMiloAwait", true, CallMethodResult.class);
+
+        assertNotNull(result);
+        assertTrue(result.getStatusCode().isGood());
+        assertEquals("out-foo", result.getOutputArguments()[0].getValue());
+    }
+
     @Test
     public void testCall1() {
         // call

components/camel-milo/src/test/java/org/apache/camel/component/milo/client/MiloClientProducerWriteFailureTest.java

@@ -0,0 +1,221 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.camel.component.milo.client;
+
+import java.lang.reflect.Field;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.apache.camel.Exchange;
+import org.apache.camel.component.milo.MiloConstants;
+import org.apache.camel.impl.DefaultCamelContext;
+import org.apache.camel.support.DefaultExchange;
+import org.eclipse.milo.opcua.stack.core.types.builtin.ExpandedNodeId;
+import org.eclipse.milo.opcua.stack.core.types.builtin.StatusCode;
+import org.eclipse.milo.opcua.stack.core.types.enumerated.BrowseDirection;
+import org.eclipse.milo.opcua.stack.core.types.structured.BrowseResult;
+import org.eclipse.milo.opcua.stack.core.types.structured.CallMethodResult;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Unit tests verifying that OPC-UA service failures from awaited write and call operations are propagated as exchange
+ * exceptions rather than being silently swallowed and reported as success.
+ *
+ * <p>
+ * Regression test for CAMEL-25694: when {@code SubscriptionManager.write()} or {@code call()} received an exceptional
+ * completion from the underlying future (e.g. a Bad_Timeout service fault) and used {@code handleAsync()}, it converted
+ * the failure into a normal completion with a null value. {@code MiloClientProducer} then reported success with a null
+ * body. The fix replaces {@code handleAsync()} with {@code whenCompleteAsync()} to preserve the original exceptional
+ * completion while still triggering the reconnection side-effect.
+ */
+class MiloClientProducerWriteFailureTest {
+
+    /**
+     * Stub connection that returns a pre-arranged future from {@code writeValue()} and {@code call()}, allowing tests
+     * to simulate service failures without a real OPC UA server.
+     */
+    static class StubMiloClientConnection extends MiloClientConnection {
+
+        private final CompletableFuture<?> writeResult;
+        private final CompletableFuture<CallMethodResult> callResult;
+
+        StubMiloClientConnection(CompletableFuture<?> writeResult, CompletableFuture<CallMethodResult> callResult) {
+            super(new MiloClientConfiguration());
+            this.writeResult = writeResult;
+            this.callResult = callResult;
+        }
+
+        @Override
+        public CompletableFuture<?> writeValue(ExpandedNodeId nodeId, Object value) {
+            return writeResult;
+        }
+
+        @Override
+        public CompletableFuture<CallMethodResult> call(ExpandedNodeId nodeId, ExpandedNodeId methodId, Object value) {
+            return callResult;
+        }
+
+        @Override
+        public CompletableFuture<?> readValues(List<ExpandedNodeId> nodeIds) {
+            return CompletableFuture.completedFuture(null);
+        }
+
+        @Override
+        public CompletableFuture<Map<ExpandedNodeId, BrowseResult>> browse(
+                List<ExpandedNodeId> expandedNodeIds, BrowseDirection direction, int nodeClasses, int maxDepth,
+                String filter, boolean includeSubTypes, int maxNodesPerRequest) {
+            return CompletableFuture.completedFuture(null);
+        }
+    }
+
+    private DefaultCamelContext camelContext;
+
+    @BeforeEach
+    void setUp() throws Exception {
+        camelContext = new DefaultCamelContext();
+        camelContext.start();
+    }
+
+    @AfterEach
+    void tearDown() throws Exception {
+        camelContext.stop();
+    }
+
+    /**
+     * Verifies that when the awaited write future completes exceptionally, the exchange receives the exception rather
+     * than reporting success with a null body.
+     */
+    @Test
+    void testAwaitedWriteServiceFailurePropagatesAsException() throws Exception {
+        RuntimeException serviceError = new RuntimeException("Bad_Timeout OPC-UA service fault");
+        CompletableFuture<StatusCode> failingWrite = new CompletableFuture<>();
+        failingWrite.completeExceptionally(serviceError);
+
+        Exchange exchange = runProducerWithStubConnection(
+                new StubMiloClientConnection(failingWrite, CompletableFuture.completedFuture(null)),
+                null, true);
+
+        assertNotNull(exchange.getException(), "Exchange must carry the service exception on failed awaited write");
+        assertInstanceOf(RuntimeException.class, exchange.getException());
+    }
+
+    /**
+     * Verifies that when the awaited call future completes exceptionally, the exchange receives the exception rather
+     * than reporting success with a null body.
+     */
+    @Test
+    void testAwaitedCallServiceFailurePropagatesAsException() throws Exception {
+        RuntimeException serviceError = new RuntimeException("Bad_Timeout OPC-UA service fault");
+        CompletableFuture<CallMethodResult> failingCall = new CompletableFuture<>();
+        failingCall.completeExceptionally(serviceError);
+
+        Exchange exchange = runProducerWithStubConnection(
+                new StubMiloClientConnection(CompletableFuture.completedFuture(null), failingCall),
+                "ns=1;s=myMethod", true);
+
+        assertNotNull(exchange.getException(), "Exchange must carry the service exception on failed awaited call");
+        assertInstanceOf(RuntimeException.class, exchange.getException());
+    }
+
+    /**
+     * Verifies that a successful awaited write does not set an exception on the exchange.
+     */
+    @Test
+    void testAwaitedWriteSuccessDoesNotSetException() throws Exception {
+        CompletableFuture<StatusCode> successWrite = CompletableFuture.completedFuture(StatusCode.GOOD);
+
+        Exchange exchange = runProducerWithStubConnection(
+                new StubMiloClientConnection(successWrite, CompletableFuture.completedFuture(null)),
+                null, true);
+
+        assertNull(exchange.getException(), "Exchange must not carry an exception on successful awaited write");
+    }
+
+    /**
+     * Verifies that non-awaited writes (fire-and-forget mode) do not propagate the exception to the exchange.
+     */
+    @Test
+    void testNonAwaitedWriteServiceFailureDoesNotSetException() throws Exception {
+        RuntimeException serviceError = new RuntimeException("Bad_Timeout OPC-UA service fault");
+        CompletableFuture<StatusCode> failingWrite = new CompletableFuture<>();
+        failingWrite.completeExceptionally(serviceError);
+
+        Exchange exchange = runProducerWithStubConnection(
+                new StubMiloClientConnection(failingWrite, CompletableFuture.completedFuture(null)),
+                null, false);
+
+        assertNull(exchange.getException(), "Non-awaited write must not propagate exceptions to the exchange");
+    }
+
+    /**
+     * Creates a {@link MiloClientProducer} backed by the given stub connection, runs process() synchronously, and
+     * returns the resulting exchange.
+     *
+     * @param stubConnection the stub connection returning pre-arranged futures
+     * @param methodIdStr    if non-null, treated as a method-call producer; otherwise a write producer
+     * @param await          whether to set {@code CamelMiloAwait=true} on the exchange
+     */
+    private Exchange runProducerWithStubConnection(
+            StubMiloClientConnection stubConnection,
+            String methodIdStr,
+            boolean await)
+            throws Exception {
+
+        MiloClientEndpoint endpoint = new MiloClientEndpoint(
+                "milo-client:opc.tcp://localhost:4840", new MiloClientComponent(), "opc.tcp://localhost:4840",
+                new MiloClientCachingConnectionManager());
+        endpoint.setCamelContext(camelContext);
+        endpoint.setNode("ns=1;s=myNode");
+        if (methodIdStr != null) {
+            endpoint.setMethod(methodIdStr);
+        }
+
+        MiloClientProducer producer = new MiloClientProducer(endpoint, await);
+
+        // Inject the stub connection via reflection to bypass doStart() which requires a real server
+        Field connectionField = MiloClientProducer.class.getDeclaredField("connection");
+        connectionField.setAccessible(true);
+        connectionField.set(producer, stubConnection);
+
+        DefaultExchange exchange = new DefaultExchange(camelContext);
+        exchange.getIn().setBody("testValue");
+        exchange.getIn().setHeader(MiloConstants.HEADER_AWAIT, await);
+
+        CountDownLatch latch = new CountDownLatch(1);
+        AtomicReference<Exchange> resultRef = new AtomicReference<>();
+
+        producer.process(exchange, done -> {
+            resultRef.set(exchange);
+            latch.countDown();
+        });
+
+        latch.await(5, TimeUnit.SECONDS);
+        assertTrue(latch.getCount() == 0, "Producer callback must complete within 5 seconds");
+        return resultRef.get();
+    }
+}