[ISSUE #4856]support mcp over xds

NOTICE

@@ -30,3 +30,31 @@ under the License.
 Also, please refer to each LICENSE.<component>.txt file, which is located in
 the 'license' directory of the distribution file, for the license terms of the
 components that this product depends on.
+
+------
+This product has a bundle Protocol Buffers��
+                      Protocol Buffers
+                   =======================
+Protocol Buffers for Go with Gadgets
+
+Copyright (c) 2013, The GoGo Authors. All rights reserved.
+http://github.com/gogo/protobuf
+
+------
+This product has a bundle Istio��
+                          Istio
+                   =======================
+
+   Copyright 2018 Istio Authors
+
+   Licensed 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.

istio/pom.xml

@@ -89,9 +89,23 @@
             <groupId>io.netty</groupId>
             <artifactId>netty-all</artifactId>
         </dependency>
+        <!-- https://mvnrepository.com/artifact/io.envoyproxy.controlplane/api -->
+        <dependency>
+            <groupId>io.envoyproxy.controlplane</groupId>
+            <artifactId>api</artifactId>
+            <version>0.1.27</version>
+        </dependency>
     </dependencies>
 
+
     <build>
+        <extensions>
+            <extension>
+                <groupId>kr.motd.maven</groupId>
+                <artifactId>os-maven-plugin</artifactId>
+                <version>1.5.0.Final</version>
+            </extension>
+        </extensions>
         <plugins>
             <plugin>
                 <artifactId>maven-source-plugin</artifactId>
@@ -118,6 +132,28 @@
                     </descriptorRefs>
                 </configuration>
             </plugin>
+            <plugin>
+                <groupId>org.xolstice.maven.plugins</groupId>
+                <artifactId>protobuf-maven-plugin</artifactId>
+                <version>0.6.1</version>
+                <configuration>
+                    <protocArtifact>com.google.protobuf:protoc:${protobuf-java.version}:exe:${os.detected.classifier}</protocArtifact>
+                    <pluginId>grpc-java</pluginId>
+                    <pluginArtifact>io.grpc:protoc-gen-grpc-java:${protoc-gen-grpc-java.version}:exe:${os.detected.classifier}</pluginArtifact>
+
+                    <useArgumentFile>true</useArgumentFile>
+                    <checkStaleness>true</checkStaleness>
+                    <staleMillis>10000</staleMillis>
+                </configuration>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>compile</goal>
+                            <goal>compile-custom</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
         </plugins>
         <resources>
             <resource>

istio/src/main/java/com/alibaba/nacos/istio/mcp/CollectionTypes.java

@@ -23,6 +23,5 @@
  * @since 1.1.4
  */
 public class CollectionTypes {
-
     public static final String SERVICE_ENTRY = "istio/networking/v1alpha3/serviceentries";
 }

istio/src/main/java/com/alibaba/nacos/istio/mcp/NacosMcpOverXdsService.java

@@ -0,0 +1,136 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * Licensed 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 com.alibaba.nacos.istio.mcp;
+
+import com.alibaba.nacos.istio.misc.Loggers;
+import com.google.protobuf.Any;
+import io.envoyproxy.envoy.service.discovery.v3.AggregatedDiscoveryServiceGrpc;
+import io.envoyproxy.envoy.service.discovery.v3.DiscoveryRequest;
+import io.envoyproxy.envoy.service.discovery.v3.DiscoveryResponse;
+import io.grpc.stub.StreamObserver;
+import istio.mcp.v1alpha1.ResourceOuterClass;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * Nacos MCP server.
+ *
+ * <p>This MCP serves as a ResourceSource defined by Istio.
+ *
+ * @author huaicheng.lzp
+ * @since 1.2.1
+ */
+@org.springframework.stereotype.Service
+public class NacosMcpOverXdsService extends AggregatedDiscoveryServiceGrpc.AggregatedDiscoveryServiceImplBase {
+
+    private final AtomicInteger connectIdGenerator = new AtomicInteger(0);
+
+    private final Map<Integer, StreamObserver<DiscoveryResponse>> connnections = new ConcurrentHashMap<>(16);
+
+    private final ConcurrentHashMap<Integer, Boolean> connectionInited = new ConcurrentHashMap<>();
+
+    private static final String MCP_RESOURCES_URL = "type.googleapis.com/istio.mcp.v1alpha1.Resource";
+
+    private static final String SERVICEENTY_TYPE = "networking.istio.io/v1alpha3/ServiceEntry";
+
+    private Map<String, ResourceOuterClass.Resource> resourceMapCache;
+
+    /**
+     * Send resources to connections.
+     *
+     * @param resourceMap all mcp resource
+     */
+    public void sendResources(Map<String, ResourceOuterClass.Resource> resourceMap) {
+        resourceMapCache = resourceMap;
+        Loggers.MAIN.info("send resources for mcpOverXds,count : {}", resourceMap.size());
+        DiscoveryResponse discoveryResponse = generateResponse(resourceMap);
+        if (Loggers.MAIN.isDebugEnabled()) {
+            Loggers.MAIN.debug("discoveryResponse:{}", discoveryResponse.toString());
+        }
+        for (StreamObserver<DiscoveryResponse> observer : connnections.values()) {
+            Loggers.MAIN.info("mcpOverXds send to:{}", observer.toString());
+            observer.onNext(discoveryResponse);
+        }
+    }
+
+    /**
+     * generate response by resource.
+     *
+     * @param resourceMap all mcp resource
+     * @return
+     */
+    private DiscoveryResponse generateResponse(Map<String, ResourceOuterClass.Resource> resourceMap) {
+        List<Any> anies = new ArrayList<>();
+        for (ResourceOuterClass.Resource resource : resourceMap.values()) {
+            Any any = Any.newBuilder().setValue(resource.toByteString()).setTypeUrl(MCP_RESOURCES_URL).build();
+            anies.add(any);
+        }
+        return DiscoveryResponse.newBuilder().addAllResources(anies)
+                .setNonce(String.valueOf(System.currentTimeMillis())).setTypeUrl(SERVICEENTY_TYPE).build();
+    }
+
+    @Override
+    public StreamObserver<DiscoveryRequest> streamAggregatedResources(
+            StreamObserver<DiscoveryResponse> responseObserver) {
+
+        int id = connectIdGenerator.incrementAndGet();
+        connnections.put(id, responseObserver);
+
+        return new StreamObserver<DiscoveryRequest>() {
+            private final int connectionId = id;
+
+            @Override
+            public void onNext(DiscoveryRequest discoveryRequest) {
+                Loggers.MAIN.info("receiving request,  {}", discoveryRequest.toString());
+
+                if (discoveryRequest.getErrorDetail() != null && discoveryRequest.getErrorDetail().getCode() != 0) {
+
+                    Loggers.MAIN.error("NACK error code: {}, message: {}", discoveryRequest.getErrorDetail().getCode(),
+                            discoveryRequest.getErrorDetail().getMessage());
+                    return;
+                }
+                if (SERVICEENTY_TYPE.equals(discoveryRequest.getTypeUrl())) {
+                    Boolean inited = connectionInited.get(id);
+                    if (inited == null || !inited) {
+                        connectionInited.put(id, true);
+                        if (resourceMapCache != null) {
+                            DiscoveryResponse discoveryResponse = generateResponse(resourceMapCache);
+                            Loggers.MAIN.info("ACK for serviceEntry discoveryRequest {}", discoveryRequest.toString());
+                            responseObserver.onNext(discoveryResponse);
+                        }
+                    }
+                }
+            }
+
+            @Override
+            public void onError(Throwable throwable) {
+                Loggers.MAIN.error("stream error.", throwable);
+                connnections.remove(connectionId);
+            }
+
+            @Override
+            public void onCompleted() {
+                responseObserver.onCompleted();
+            }
+        };
+
+    }
+}

istio/src/main/java/com/alibaba/nacos/istio/mcp/NacosMcpServer.java

@@ -27,7 +27,6 @@
 import javax.annotation.PostConstruct;
 import java.io.IOException;
 
-
 /**
  * Nacos MCP server.
  *
@@ -52,6 +51,12 @@ public class NacosMcpServer {
     @Autowired
     private NacosMcpService nacosMcpService;
 
+    @Autowired
+    private NacosMcpOverXdsService nacosMcpOverXdsService;
+
+    @Autowired
+    private NacosToMcpResources nacosToMcpResources;
+
     /**
      * Start.
      *
@@ -67,9 +72,9 @@ public void start() throws IOException {
         Loggers.MAIN.info("MCP server, starting Nacos MCP server...");
 
         server = ServerBuilder.forPort(port).addService(ServerInterceptors.intercept(nacosMcpService, intercepter))
-                .build();
+                .addService(ServerInterceptors.intercept(nacosMcpOverXdsService, intercepter)).build();
         server.start();
-
+        nacosToMcpResources.start();
         Runtime.getRuntime().addShutdownHook(new Thread() {
             @Override
             public void run() {