Add lazy-loading DataTypeTree implementation

milo-examples/client-examples/src/main/java/org/eclipse/milo/examples/client/LegacyDataTypeDictionaryExample.java

@@ -12,8 +12,8 @@
 
 import java.util.concurrent.CompletableFuture;
 import org.eclipse.milo.opcua.sdk.client.OpcUaClient;
-import org.eclipse.milo.opcua.sdk.client.OpcUaClient.DefaultDataTypeManagerInitializer;
 import org.eclipse.milo.opcua.sdk.client.dtd.LegacyDataTypeManagerInitializer;
+import org.eclipse.milo.opcua.sdk.client.typetree.DataTypeManagerFactory;
 import org.eclipse.milo.opcua.stack.core.security.SecurityPolicy;
 import org.eclipse.milo.opcua.stack.core.types.builtin.DataValue;
 import org.eclipse.milo.opcua.stack.core.types.builtin.ExtensionObject;
@@ -27,7 +27,8 @@
  * specification.
  *
  * <p>This was the default (and only supported mechanism) in Milo 0.6.x and earlier. Milo 1.x now
- * uses the DataTypeDefinition attribute instead via {@link DefaultDataTypeManagerInitializer}.
+ * uses the DataTypeDefinition attribute instead via {@link
+ * DataTypeManagerFactory.DefaultInitializer}.
  *
  * <p>Requires a server that still supports DataTypeDictionary, such as the Unified Automation C++
  * demo server, which this example is configured for by default.
@@ -42,7 +43,8 @@ public static void main(String[] args) throws Exception {
 
   @Override
   public void run(OpcUaClient client, CompletableFuture<OpcUaClient> future) throws Exception {
-    client.setDataTypeManagerInitializer(new LegacyDataTypeManagerInitializer(client));
+    client.setDynamicDataTypeManagerFactory(
+        DataTypeManagerFactory.eager(new LegacyDataTypeManagerInitializer(client)));
 
     client.connect();
 

opc-ua-sdk/dtd-reader/src/main/java/org/eclipse/milo/opcua/sdk/client/dtd/LegacyDataTypeManagerInitializer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2024 the Eclipse Milo Authors
+ * Copyright (c) 2025 the Eclipse Milo Authors
  *
  * This program and the accompanying materials are made
  * available under the terms of the Eclipse Public License 2.0
@@ -12,14 +12,23 @@
 
 import java.util.List;
 import org.eclipse.milo.opcua.sdk.client.OpcUaClient;
+import org.eclipse.milo.opcua.sdk.client.typetree.DataTypeManagerFactory;
 import org.eclipse.milo.opcua.sdk.core.dtd.generic.StructCodec;
 import org.eclipse.milo.opcua.sdk.core.typetree.DataTypeTree;
 import org.eclipse.milo.opcua.stack.core.NamespaceTable;
 import org.eclipse.milo.opcua.stack.core.UaException;
 import org.eclipse.milo.opcua.stack.core.types.DataTypeDictionary;
 import org.eclipse.milo.opcua.stack.core.types.DataTypeManager;
 
-public class LegacyDataTypeManagerInitializer implements OpcUaClient.DataTypeManagerInitializer {
+/**
+ * A {@link DataTypeManagerFactory.Initializer} that reads legacy DataTypeDictionary information
+ * from the server and registers codecs based on that.
+ *
+ * <p>This is for servers that support the legacy (OPC UA <= 1.03) DataTypeDictionary mechanism.
+ *
+ * @see DataTypeManagerFactory#eager(DataTypeManagerFactory.Initializer)
+ */
+public class LegacyDataTypeManagerInitializer implements DataTypeManagerFactory.Initializer {
 
   private final OpcUaClient client;
   private final BinaryCodecFactory codecFactory;

opc-ua-sdk/integration-tests/src/test/java/org/eclipse/milo/opcua/sdk/client/typetree/DataTypeTreeFactoryTest.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2025 the Eclipse Milo Authors
+ *
+ * This program and the accompanying materials are made
+ * available under the terms of the Eclipse Public License 2.0
+ * which is available at https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+
+package org.eclipse.milo.opcua.sdk.client.typetree;
+
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNotSame;
+
+import org.eclipse.milo.opcua.sdk.core.typetree.DataTypeTree;
+import org.eclipse.milo.opcua.sdk.test.AbstractClientServerTest;
+import org.eclipse.milo.opcua.stack.core.NodeIds;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInstance;
+
+@TestInstance(TestInstance.Lifecycle.PER_CLASS)
+public class DataTypeTreeFactoryTest extends AbstractClientServerTest {
+
+  @Test
+  void defaultFactoryCreatesEagerTree() throws Exception {
+    DataTypeTree tree = client.getDataTypeTree();
+
+    assertNotNull(tree);
+    assertNotNull(tree.getDataType(NodeIds.Int32));
+    assertNotNull(tree.getDataType(NodeIds.String));
+    assertNotNull(tree.getDataType(NodeIds.XVType));
+  }
+
+  @Test
+  void setDataTypeTreeFactoryToLazy() throws Exception {
+    client.setDataTypeTreeFactory(DataTypeTreeFactory.lazy());
+
+    DataTypeTree tree = client.getDataTypeTree();
+
+    assertNotNull(tree);
+    assertInstanceOf(LazyClientDataTypeTree.class, tree);
+    assertNotNull(tree.getDataType(NodeIds.Int32));
+    assertNotNull(tree.getDataType(NodeIds.String));
+    assertNotNull(tree.getDataType(NodeIds.XVType));
+  }
+
+  @Test
+  void setDataTypeTreeFactoryResetsCache() throws Exception {
+    client.setDataTypeTreeFactory(DataTypeTreeFactory.eager());
+
+    DataTypeTree tree1 = client.getDataTypeTree();
+    assertNotNull(tree1);
+
+    client.setDataTypeTreeFactory(DataTypeTreeFactory.lazy());
+
+    DataTypeTree tree2 = client.getDataTypeTree();
+    assertNotNull(tree2);
+
+    assertNotSame(tree1, tree2);
+    assertInstanceOf(LazyClientDataTypeTree.class, tree2);
+  }
+
+  @Test
+  void customFactoryIsUsed() throws Exception {
+    var customTree = new LazyClientDataTypeTree(client);
+
+    client.setDataTypeTreeFactory(c -> customTree);
+
+    DataTypeTree tree = client.getDataTypeTree();
+
+    assertNotNull(tree);
+    assertInstanceOf(LazyClientDataTypeTree.class, tree);
+  }
+}