Polish apache#3946 : Dubbo Cloud Native : To Add Dubbo metadata service

dubbo-common/src/main/java/org/apache/dubbo/common/metadata/DubboMetadataServiceExporter.java

@@ -0,0 +1,45 @@
+/*
+ * 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.dubbo.common.metadata;
+
+import org.apache.dubbo.common.URL;
+
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * The exporter of {@link DubboMetadataService}
+ *
+ * @see DubboMetadataService
+ * @see #export()
+ * @see #unexport()
+ * @since 2.7.2
+ */
+public interface DubboMetadataServiceExporter {
+
+    /**
+     * Exports the {@link DubboMetadataService} as a Dubbo service
+     *
+     * @return the exported {@link URL URLs}
+     */
+    List<URL> export();
+
+    /**
+     * Unexports the {@link DubboMetadataService}
+     */
+    void unexport();
+}

dubbo-common/src/main/java/org/apache/dubbo/common/metadata/InMemoryMetadataService.java

@@ -32,7 +32,7 @@
 import static org.apache.dubbo.common.URL.buildKey;
 
 /**
- * The {@link DubboMetadataService} implementation stores the metadata of Dubbo services in memory when they exported, and
+ * The {@link DubboMetadataService} implementation stores the metadata of Dubbo services in memory when they exported
  *
  * @since 2.7.2
  */

dubbo-config/dubbo-config-api/src/main/java/org/apache/dubbo/config/metadata/ConfigurableDubboMetadataServiceExporter.java

@@ -0,0 +1,62 @@
+/*
+ * 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.dubbo.config.metadata;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.common.logger.Logger;
+import org.apache.dubbo.common.logger.LoggerFactory;
+import org.apache.dubbo.common.metadata.DubboMetadataService;
+import org.apache.dubbo.common.metadata.DubboMetadataServiceExporter;
+import org.apache.dubbo.config.ApplicationConfig;
+import org.apache.dubbo.config.ProtocolConfig;
+import org.apache.dubbo.config.RegistryConfig;
+import org.apache.dubbo.config.ServiceConfig;
+
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * @since 2.7.2
+ */
+public class ConfigurableDubboMetadataServiceExporter implements DubboMetadataServiceExporter {
+
+    private final Logger logger = LoggerFactory.getLogger(getClass());
+
+    private Optional<DubboMetadataService> dubboMetadataService;
+
+    private ApplicationConfig applicationConfig;
+
+    private List<ProtocolConfig> protocols;
+
+    private List<RegistryConfig> registries;
+
+    /**
+     * The ServiceConfig of DubboMetadataConfigService to be exported, can be nullable.
+     */
+    private ServiceConfig<DubboMetadataService> serviceConfig;
+
+
+    @Override
+    public List<URL> export() {
+        return null;
+    }
+
+    @Override
+    public void unexport() {
+
+    }
+}