企业级分布式MCP方案

无聊的郭涛2025-05-02 22:22

飞书原文档链接地址：https://ik3te1knhq.feishu.cn/wiki/D8kSwC9tFi61CMkRdd8cMxNTnpg

企业级分布式 MCP 方案

背景：现阶段 MCP Client 和 MCP Server 是一对一的连接方式，若当前 MCP Server 挂掉了，那么 MCP Client 便不能使用 MCP Server 提供的工具能力。工具稳定性的提供得不到保证

解决：做了一些分布式 Client 连接的探索，一个 MCP Client 端可以连接多个 MCP Server（分布式部署），目前采用的方案如下：

  1. 新建一个包含服务名和对应连接的类

  2. 另外实现监听机制，可以动态的应对 MCP Server 节点上下线，去动态调整 mcpAsyncClientList

  3. （读操作）获取 MCP Server 相关信息的，采用从 mcpAsyncClientList 列表中随机中获取一个去发起请求，比如获取工具列表信息

  4. （写操作）对应 MCP Server 需要更改的信息，由 MCP Client 端发起，需要修改所有的 MCP Server

public class LoadbalancedAsyncClient implements EventListener { private String serviceName; private List<McpAsyncClient> mcpAsyncClientList;

} 给社区贡献代码：https://github.com/alibaba/spring-ai-alibaba/pull/755

模块代码解析

yaml 文件

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spring:
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  ai:
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    mcp:
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      client:
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        enabled: true
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        name: mcp-client-webflux
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        version: 1.0.0
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        type: SYNC
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        nacos-enabled: true # 开启nacos-client配置，启动分布式
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    alibaba:
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      mcp:
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        nacos: ## nacos的基础配置信息
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          enabled: true
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          server-addr: <nacos-sever-addr>
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          service-namespace: <nacos-namespace>
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          service-group: <nacos-group>
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​
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        client:
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          sse:
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            connections: // 注册在nacos的MCP Server服务，这里mcp-server1代表多节点
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              nacos-server1: mcp-server1
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              nacos-server2: mcp-server2

自动注入部分

NacosMcpSseClientProperties（配置类）

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@ConfigurationProperties("spring.ai.alibaba.mcp.client.sse")
public class NacosMcpSseClientProperties {

    public static final String _CONFIG_PREFIX _= "spring.ai.alibaba.mcp.client.sse";

    private final Map<String, String> connections = new HashMap<>();

    public Map<String, String> getConnections() {
       return connections;
    }

}

NacosMcpSseClientAutoConfiguration

提供 Map<String, List<NamedClientMcpTransport>> 的 bean

  • 键代表服务名

  • 值为对应的后续连接的 WebFluxSseClientTransport 列表

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@AutoConfiguration
@EnableConfigurationProperties({ NacosMcpSseClientProperties.class, NacosMcpRegistryProperties.class })
public class NacosMcpSseClientAutoConfiguration {

    private static final Logger _logger _= LoggerFactory._getLogger_(NacosMcpSseClientAutoConfiguration.class);

    public NacosMcpSseClientAutoConfiguration() {
    }

    @Bean
    public NamingService nacosNamingService(NacosMcpRegistryProperties nacosMcpRegistryProperties) {
       Properties nacosProperties = nacosMcpRegistryProperties.getNacosProperties();
       try {
          return NamingFactory._createNamingService_(nacosProperties);
       }
       catch (NacosException e) {
          throw new RuntimeException(e);
       }
    }

    @Bean(name = "server2NamedTransport")
    public Map<String, List<NamedClientMcpTransport>> server2NamedTransport(
          NacosMcpSseClientProperties nacosMcpSseClientProperties, NamingService namingService,
          ObjectProvider<WebClient.Builder> webClientBuilderProvider,
          ObjectProvider<ObjectMapper> objectMapperProvider) {
       Map<String, List<NamedClientMcpTransport>> server2NamedTransport = new HashMap<>();
       WebClient.Builder webClientBuilderTemplate = (WebClient.Builder) webClientBuilderProvider
          .getIfAvailable(WebClient::_builder_);
       ObjectMapper objectMapper = (ObjectMapper) objectMapperProvider.getIfAvailable(ObjectMapper::new);

       Map<String, String> connections = nacosMcpSseClientProperties.getConnections();
       connections.forEach((serviceKey, serviceName) -> {
          try {
             List<Instance> instances = namingService.selectInstances(serviceName, true);
             List<NamedClientMcpTransport> namedTransports = new ArrayList<>();
             for (Instance instance : instances) {
                String url = instance.getMetadata().getOrDefault("scheme", "http") + "://" + instance.getIp() + ":"
                      + instance.getPort();

                WebClient.Builder webClientBuilder = webClientBuilderTemplate.clone().baseUrl(url);
                WebFluxSseClientTransport transport = new WebFluxSseClientTransport(webClientBuilder, objectMapper);
                namedTransports
                   .add(new NamedClientMcpTransport(serviceName + "-" + instance.getInstanceId(), transport));
             }

             server2NamedTransport.put(serviceName, namedTransports);
          }
          catch (NacosException e) {
             _logger_.error("nacos naming service: {} error", serviceName, e);
          }
       });
       return server2NamedTransport;
    }

}

NacosMcpClientAutoConfiguration

提供和 MCP Server 进行交互的客户端

  • List<LoadbalancedMcpAsyncClient>

  • List<LoadbalancedMcpSyncClient>

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@AutoConfiguration(after = { NacosMcpSseClientAutoConfiguration.class, McpClientAutoConfiguration.class })
@ConditionalOnClass({ McpSchema.class })
@EnableConfigurationProperties({ McpClientCommonProperties.class })
@ConditionalOnProperty(prefix = "spring.ai.mcp.client", name = { "nacos-enabled" }, havingValue = "true",
       matchIfMissing = false)
public class NacosMcpClientAutoConfiguration {

    public NacosMcpClientAutoConfiguration() {
    }

    private String connectedClientName(String clientName, String serverConnectionName) {
       return clientName + " - " + serverConnectionName;
    }

    @Bean
    @ConditionalOnProperty(prefix = "spring.ai.mcp.client", name = { "type" }, havingValue = "SYNC",
          matchIfMissing = true)
    public List<LoadbalancedMcpSyncClient> loadbalancedMcpSyncClientList(
          ObjectProvider<McpSyncClientConfigurer> mcpSyncClientConfigurerProvider,
          McpClientCommonProperties commonProperties,
          @Qualifier("server2NamedTransport") ObjectProvider<Map<String, List<NamedClientMcpTransport>>> server2NamedTransportProvider,
          ObjectProvider<NamingService> namingServiceProvider) {
       NamingService namingService = namingServiceProvider.getObject();
       McpSyncClientConfigurer mcpSyncClientConfigurer = mcpSyncClientConfigurerProvider.getObject();

       List<LoadbalancedMcpSyncClient> loadbalancedMcpSyncClients = new ArrayList<>();
       Map<String, List<NamedClientMcpTransport>> server2NamedTransport = server2NamedTransportProvider.getObject();
       for (Map.Entry<String, List<NamedClientMcpTransport>> entry : server2NamedTransport.entrySet()) {
          String serviceName = entry.getKey();
          List<NamedClientMcpTransport> namedTransports = entry.getValue();
          List<McpSyncClient> mcpSyncClients = new ArrayList<>();

          McpSyncClient syncClient;
          for (NamedClientMcpTransport namedTransport : namedTransports) {
             McpSchema.Implementation clientInfo = new McpSchema.Implementation(
                   this.connectedClientName(commonProperties.getName(), namedTransport.name()),
                   commonProperties.getVersion());
             McpClient.SyncSpec syncSpec = McpClient._sync_(namedTransport.transport())
                .clientInfo(clientInfo)
                .requestTimeout(commonProperties.getRequestTimeout());
             syncSpec = mcpSyncClientConfigurer.configure(namedTransport.name(), syncSpec);
             syncClient = syncSpec.build();
             if (commonProperties.isInitialized()) {
                syncClient.initialize();
             }
             mcpSyncClients.add(syncClient);
          }

          LoadbalancedMcpSyncClient loadbalancedMcpSyncClient = LoadbalancedMcpSyncClient._builder_()
             .serviceName(serviceName)
             .mcpSyncClientList(mcpSyncClients)
             .namingService(namingService)
             .build();
          loadbalancedMcpSyncClient.subscribe();

          loadbalancedMcpSyncClients.add(loadbalancedMcpSyncClient);
       }

       return loadbalancedMcpSyncClients;

    }

    @Bean
    @ConditionalOnProperty(prefix = "spring.ai.mcp.client", name = { "type" }, havingValue = "ASYNC")
    public List<LoadbalancedMcpAsyncClient> loadbalancedMcpAsyncClientList(
          ObjectProvider<McpAsyncClientConfigurer> mcpAsyncClientConfigurerProvider,
          McpClientCommonProperties commonProperties,
          @Qualifier("server2NamedTransport") ObjectProvider<Map<String, List<NamedClientMcpTransport>>> server2NamedTransportProvider,
          ObjectProvider<NamingService> namingServiceProvider) {
       NamingService namingService = namingServiceProvider.getObject();
       McpAsyncClientConfigurer mcpAsyncClientConfigurer = mcpAsyncClientConfigurerProvider.getObject();

       List<LoadbalancedMcpAsyncClient> loadbalancedMcpAsyncClients = new ArrayList<>();
       Map<String, List<NamedClientMcpTransport>> server2NamedTransport = server2NamedTransportProvider.getObject();
       for (Map.Entry<String, List<NamedClientMcpTransport>> entry : server2NamedTransport.entrySet()) {
          String serviceName = entry.getKey();
          List<NamedClientMcpTransport> namedTransports = entry.getValue();
          List<McpAsyncClient> mcpAsyncClients = new ArrayList<>();

          McpAsyncClient asyncClient;
          for (NamedClientMcpTransport namedTransport : namedTransports) {
             McpSchema.Implementation clientInfo = new McpSchema.Implementation(
                   this.connectedClientName(commonProperties.getName(), namedTransport.name()),
                   commonProperties.getVersion());
             McpClient.AsyncSpec asyncSpec = McpClient._async_(namedTransport.transport())
                .clientInfo(clientInfo)
                .requestTimeout(commonProperties.getRequestTimeout());
             asyncSpec = mcpAsyncClientConfigurer.configure(namedTransport.name(), asyncSpec);
             asyncClient = asyncSpec.build();
             if (commonProperties.isInitialized()) {
                asyncClient.initialize().block();
             }

             mcpAsyncClients.add(asyncClient);
          }

          LoadbalancedMcpAsyncClient loadbalancedMcpAsyncClient = LoadbalancedMcpAsyncClient._builder_()
             .serviceName(serviceName)
             .mcpAsyncClientList(mcpAsyncClients)
             .namingService(namingService)
             .build();

          loadbalancedMcpAsyncClient.subscribe();

          loadbalancedMcpAsyncClients.add(loadbalancedMcpAsyncClient);
       }
       return loadbalancedMcpAsyncClients;
    }

}

Client 端部分

LoadbalancedMcpAsyncClient

各字段含义：

  • String serviceName：MCP Server 注册的服务名称

  • List<McpAsyncClient> mcpAsyncClientList：对应的多节点客户端

  • NamingService namingService：Nacos 服务

  • List<Instance> instances：Nacos 中 MCP Server 的实例列表

其余方法的使用和 McpAsyncClient 保持一致，已经全面封装好了

  1. 读操作：通过 getMcpAsyncClient()方法轮询得到 McpAsyncClient 列表

  2. 写操作：对所有 List<McpAsyncClient> 进行操作

通过实现 EventListener 接口，动态增加 or 减少 McpAsyncClient

复制代码 
public class LoadbalancedMcpAsyncClient implements EventListener {

    private static final Logger _logger _= LoggerFactory._getLogger_(LoadbalancedMcpAsyncClient.class);

    private final String serviceName;

    private final List<McpAsyncClient> mcpAsyncClientList;

    private final AtomicInteger currentIndex = new AtomicInteger(0);

    private final NamingService namingService;

    private List<Instance> instances;

    public LoadbalancedMcpAsyncClient(String serviceName, List<McpAsyncClient> mcpAsyncClientList,
          NamingService namingService) {
       Assert._notNull_(serviceName, "serviceName cannot be null");
       Assert._notNull_(mcpAsyncClientList, "mcpAsyncClientList cannot be null");
       Assert._notNull_(namingService, "namingService cannot be null");
       this.serviceName = serviceName;
       this.mcpAsyncClientList = mcpAsyncClientList;

       try {
          this.namingService = namingService;
          this.instances = namingService.selectInstances(serviceName, true);
       }
       catch (NacosException e) {
          throw new RuntimeException(String._format_("Failed to get instances for service: %s", serviceName));
       }
    }

    public void subscribe() {
       try {
          this.namingService.subscribe(this.serviceName, this);
       }
       catch (NacosException e) {
          throw new RuntimeException(String._format_("Failed to subscribe to service: %s", this.serviceName));
       }
    }

    public String getServiceName() {
       return serviceName;
    }

    public List<McpAsyncClient> getMcpAsyncClientList() {
       return mcpAsyncClientList;
    }

    public NamingService getNamingService() {
       return this.namingService;
    }

    public List<Instance> getInstances() {
       return this.instances;
    }

    private McpAsyncClient getMcpAsyncClient() {
       if (mcpAsyncClientList.isEmpty()) {
          throw new IllegalStateException("No McpAsyncClient available");
       }
       int index = currentIndex.getAndIncrement() % mcpAsyncClientList.size();
       return mcpAsyncClientList.get(index);
    }

    // ------------------------------------------------------------------------------------------------------------------------------------------------

    public McpSchema.ServerCapabilities getServerCapabilities() {
       return getMcpAsyncClient().getServerCapabilities();
    }

    public McpSchema.Implementation getServerInfo() {
       return getMcpAsyncClient().getServerInfo();
    }

    public boolean isInitialized() {
       return getMcpAsyncClient().isInitialized();
    }

    public McpSchema.ClientCapabilities getClientCapabilities() {
       return getMcpAsyncClient().getClientCapabilities();
    }

    public McpSchema.Implementation getClientInfo() {
       return getMcpAsyncClient().getClientInfo();
    }

    public void close() {
       Iterator<McpAsyncClient> iterator = mcpAsyncClientList.iterator();
       while (iterator.hasNext()) {
          McpAsyncClient mcpAsyncClient = iterator.next();
          mcpAsyncClient.close();
          iterator.remove();
          _logger_.info("Closed and removed McpSyncClient: {}", mcpAsyncClient.getClientInfo().name());
       }
    }

    public Mono<Void> closeGracefully() {
       Iterator<McpAsyncClient> iterator = mcpAsyncClientList.iterator();
       List<Mono<Void>> closeMonos = new ArrayList<>();
       while (iterator.hasNext()) {
          McpAsyncClient mcpAsyncClient = iterator.next();
          Mono<Void> voidMono = mcpAsyncClient.closeGracefully().doOnSuccess(v -> {
             iterator.remove();
             _logger_.info("Closed and removed McpAsyncClient: {}", mcpAsyncClient.getClientInfo().name());
          });
          closeMonos.add(voidMono);
       }
       return Mono._when_(closeMonos);
    }

    public Mono<Object> ping() {
       return getMcpAsyncClient().ping();
    }

    public Mono<Void> addRoot(McpSchema.Root root) {
       return Mono._when_(mcpAsyncClientList.stream()
          .map(mcpAsyncClient -> mcpAsyncClient.addRoot(root))
          .collect(Collectors._toList_()));
    }

    public Mono<Void> removeRoot(String rootUri) {
       return Mono._when_(mcpAsyncClientList.stream()
          .map(mcpAsyncClient -> mcpAsyncClient.removeRoot(rootUri))
          .collect(Collectors._toList_()));
    }

    public Mono<Void> rootsListChangedNotification() {
       return Mono._when_(mcpAsyncClientList.stream()
          .map(McpAsyncClient::rootsListChangedNotification)
          .collect(Collectors._toList_()));
    }

    public Mono<McpSchema.CallToolResult> callTool(McpSchema.CallToolRequest callToolRequest) {
       return getMcpAsyncClient().callTool(callToolRequest);
    }

    public Mono<McpSchema.ListToolsResult> listTools() {
       return getMcpAsyncClient().listTools();
    }

    public Mono<McpSchema.ListToolsResult> listTools(String cursor) {
       return getMcpAsyncClient().listTools(cursor);
    }

    public Mono<McpSchema.ListResourcesResult> listResources() {
       return getMcpAsyncClient().listResources();
    }

    public Mono<McpSchema.ListResourcesResult> listResources(String cursor) {
       return getMcpAsyncClient().listResources(cursor);
    }

    public Mono<McpSchema.ReadResourceResult> readResource(McpSchema.Resource resource) {
       return getMcpAsyncClient().readResource(resource);
    }

    public Mono<McpSchema.ReadResourceResult> readResource(McpSchema.ReadResourceRequest readResourceRequest) {
       return getMcpAsyncClient().readResource(readResourceRequest);
    }

    public Mono<McpSchema.ListResourceTemplatesResult> listResourceTemplates() {
       return getMcpAsyncClient().listResourceTemplates();
    }

    public Mono<McpSchema.ListResourceTemplatesResult> listResourceTemplates(String cursor) {
       return getMcpAsyncClient().listResourceTemplates(cursor);
    }

    public Mono<Void> subscribeResource(McpSchema.SubscribeRequest subscribeRequest) {
       return Mono._when_(mcpAsyncClientList.stream()
          .map(mcpAsyncClient -> mcpAsyncClient.subscribeResource(subscribeRequest))
          .collect(Collectors._toList_()));
    }

    public Mono<Void> unsubscribeResource(McpSchema.UnsubscribeRequest unsubscribeRequest) {
       return Mono._when_(mcpAsyncClientList.stream()
          .map(mcpAsyncClient -> mcpAsyncClient.unsubscribeResource(unsubscribeRequest))
          .collect(Collectors._toList_()));
    }

    public Mono<McpSchema.ListPromptsResult> listPrompts() {
       return getMcpAsyncClient().listPrompts();
    }

    public Mono<McpSchema.ListPromptsResult> listPrompts(String cursor) {
       return getMcpAsyncClient().listPrompts(cursor);
    }

    public Mono<McpSchema.GetPromptResult> getPrompt(McpSchema.GetPromptRequest getPromptRequest) {
       return getMcpAsyncClient().getPrompt(getPromptRequest);
    }

    public Mono<Void> setLoggingLevel(McpSchema.LoggingLevel loggingLevel) {
       return Mono._when_(mcpAsyncClientList.stream()
          .map(mcpAsyncClient -> mcpAsyncClient.setLoggingLevel(loggingLevel))
          .collect(Collectors._toList_()));
    }

    // ------------------------------------------------------------------------------------------------------------------------------------------------

    @Override
    public void onEvent(Event event) {
       if (event instanceof NamingEvent namingEvent) {
          if (this.serviceName.equals(namingEvent.getServiceName())) {
             _logger_.info("Received service instance change event for service: {}", namingEvent.getServiceName());
             List<Instance> instances = namingEvent.getInstances();
             _logger_.info("Updated instances count: {}", instances.size());
             // 打印每个实例的详细信息
             instances.forEach(instance -> {
                _logger_.info("Instance: {}:{} (Healthy: {}, Enabled: {}, Metadata: {})", instance.getIp(),
                      instance.getPort(), instance.isHealthy(), instance.isEnabled(),
                      JacksonUtils._toJson_(instance.getMetadata()));
             });
             updateClientList(instances);
          }
       }
    }

    private void updateClientList(List<Instance> currentInstances) {
       McpClientCommonProperties commonProperties = ApplicationContextHolder._getBean_(McpClientCommonProperties.class);
       McpAsyncClientConfigurer mcpSyncClientConfigurer = ApplicationContextHolder
          ._getBean_(McpAsyncClientConfigurer.class);
       ObjectMapper objectMapper = ApplicationContextHolder._getBean_(ObjectMapper.class);
       WebClient.Builder webClientBuilderTemplate = ApplicationContextHolder._getBean_(WebClient.Builder.class);

       // 移除的实例列表
       List<Instance> removeInstances = instances.stream()
          .filter(instance -> !currentInstances.contains(instance))
          .collect(Collectors._toList_());

       // 新增的实例列表
       List<Instance> addInstances = currentInstances.stream()
          .filter(instance -> !instances.contains(instance))
          .collect(Collectors._toList_());

       // 删除McpAsyncClient实例
       List<String> clientInfoNames = removeInstances.stream()
          .map(instance -> connectedClientName(commonProperties.getName(),
                this.serviceName + "-" + instance.getInstanceId()))
          .toList();
       Iterator<McpAsyncClient> iterator = mcpAsyncClientList.iterator();
        while (iterator.hasNext()) {
            McpAsyncClient mcpAsyncClient = iterator.next();
            McpSchema.Implementation clientInfo = mcpAsyncClient.getClientInfo();
            if (clientInfoNames.contains(clientInfo.name())) {
               _logger_.info("Removing McpAsyncClient: {}", clientInfo.name());
               mcpAsyncClient.closeGracefully().subscribe(v -> {
                  iterator.remove();
               }, e -> _logger_.error("Failed to remove McpAsyncClient: {}", clientInfo.name(), e));
            }
        }

        // 新增McpAsyncClient实例
        McpAsyncClient asyncClient;
        for (Instance instance : addInstances) {
            String baseUrl = instance.getMetadata().getOrDefault("scheme", "http") + "://" + instance.getIp() + ":"
                  + instance.getPort();
            WebClient.Builder webClientBuilder = webClientBuilderTemplate.clone().baseUrl(baseUrl);
            WebFluxSseClientTransport transport = new WebFluxSseClientTransport(webClientBuilder, objectMapper);
            NamedClientMcpTransport namedTransport = new NamedClientMcpTransport(
                  serviceName + "-" + instance.getInstanceId(), transport);
        
            McpSchema.Implementation clientInfo = new McpSchema.Implementation(
                  this.connectedClientName(commonProperties.getName(), namedTransport.name()),
                  commonProperties.getVersion());
            McpClient.AsyncSpec asyncSpec = McpClient._async_(namedTransport.transport())
               .clientInfo(clientInfo)
               .requestTimeout(commonProperties.getRequestTimeout());
            asyncSpec = mcpSyncClientConfigurer.configure(namedTransport.name(), asyncSpec);
            asyncClient = asyncSpec.build();
            if (commonProperties.isInitialized()) {
               asyncClient.initialize().block();
            }
            _logger_.info("Added McpAsyncClient: {}", clientInfo.name());
            mcpAsyncClientList.add(asyncClient);
        }

    private String connectedClientName(String clientName, String serverConnectionName) {
       return clientName + " - " + serverConnectionName;
    }

    public static Builder builder() {
       return new Builder();
    }

    public static class Builder {

       private String serviceName;

       private List<McpAsyncClient> mcpAsyncClientList;

       private NamingService namingService;

       public Builder serviceName(String serviceName) {
          this.serviceName = serviceName;
          return this;
       }

       public Builder mcpAsyncClientList(List<McpAsyncClient> mcpAsyncClientList) {
          this.mcpAsyncClientList = mcpAsyncClientList;
          return this;
       }

       public Builder namingService(NamingService namingService) {
          this.namingService = namingService;
          return this;
       }

       public LoadbalancedMcpAsyncClient build() {
          return new LoadbalancedMcpAsyncClient(this.serviceName, this.mcpAsyncClientList, this.namingService);
       }

    }

}

LoadbalancedMcpSyncClient

同上

复制代码 
public class LoadbalancedMcpSyncClient implements EventListener {

    private static final Logger _logger _= LoggerFactory._getLogger_(LoadbalancedMcpAsyncClient.class);

    private final String serviceName;

    private final List<McpSyncClient> mcpSyncClientList;

    private final AtomicInteger currentIndex = new AtomicInteger(0);

    private final NamingService namingService;

    private List<Instance> instances;

    public LoadbalancedMcpSyncClient(String serviceName, List<McpSyncClient> mcpSyncClientList,
          NamingService namingService) {
       Assert._notNull_(serviceName, "Service name must not be null");
       Assert._notNull_(mcpSyncClientList, "McpSyncClient list must not be null");
       Assert._notNull_(namingService, "NamingService must not be null");

       this.serviceName = serviceName;
       this.mcpSyncClientList = mcpSyncClientList;

       try {
          this.namingService = namingService;
          this.instances = namingService.selectInstances(serviceName, true);
       }
       catch (NacosException e) {
          throw new RuntimeException(String._format_("Failed to get instances for service: %s", serviceName));
       }
    }

    public void subscribe() {
       try {
          this.namingService.subscribe(this.serviceName, this);
       }
       catch (NacosException e) {
          throw new RuntimeException(String._format_("Failed to subscribe to service: %s", this.serviceName));
       }
    }

    public String getServiceName() {
       return this.serviceName;
    }

    public List<McpSyncClient> getMcpSyncClientList() {
       return this.mcpSyncClientList;
    }

    public NamingService getNamingService() {
       return this.namingService;
    }

    public List<Instance> getInstances() {
       return this.instances;
    }

    private McpSyncClient getMcpSyncClient() {
       if (mcpSyncClientList.isEmpty()) {
          throw new IllegalStateException("No McpAsyncClient available");
       }
       int index = currentIndex.getAndIncrement() % mcpSyncClientList.size();
       return mcpSyncClientList.get(index);
    }

    // ------------------------------------------------------------------------------------------------------------------------------------------------
    public McpSchema.ServerCapabilities getServerCapabilities() {
       return getMcpSyncClient().getServerCapabilities();
    }

    public McpSchema.Implementation getServerInfo() {
       return getMcpSyncClient().getServerInfo();
    }

    public McpSchema.ClientCapabilities getClientCapabilities() {
       return getMcpSyncClient().getClientCapabilities();
    }

    public McpSchema.Implementation getClientInfo() {
       return getMcpSyncClient().getClientInfo();
    }

    public void close() {
       Iterator<McpSyncClient> iterator = mcpSyncClientList.iterator();
       while (iterator.hasNext()) {
          McpSyncClient mcpSyncClient = iterator.next();
          mcpSyncClient.close();
          iterator.remove();
          _logger_.info("Closed and removed McpSyncClient: {}", mcpSyncClient.getClientInfo().name());
       }
    }

    public boolean closeGracefully() {
       List<Boolean> flagList = new ArrayList<>();
       Iterator<McpSyncClient> iterator = mcpSyncClientList.iterator();
       while (iterator.hasNext()) {
          McpSyncClient mcpSyncClient = iterator.next();
          boolean flag = mcpSyncClient.closeGracefully();
          flagList.add(flag);
          if (flag) {
             iterator.remove();
             _logger_.info("Closed and removed McpSyncClient: {}", mcpSyncClient.getClientInfo().name());
          }
       }
       return !flagList.stream().allMatch(flag -> flag);
    }

    public Object ping() {
       return getMcpSyncClient().ping();
    }

    public void addRoot(McpSchema.Root root) {
       for (McpSyncClient mcpSyncClient : mcpSyncClientList) {
          mcpSyncClient.addRoot(root);
       }
    }

    public void removeRoot(String rootUri) {
       for (McpSyncClient mcpSyncClient : mcpSyncClientList) {
          mcpSyncClient.removeRoot(rootUri);
       }
    }

    public McpSchema.CallToolResult callTool(McpSchema.CallToolRequest callToolRequest) {
       return getMcpSyncClient().callTool(callToolRequest);
    }

    public McpSchema.ListToolsResult listTools() {
       return getMcpSyncClient().listTools();
    }

    public McpSchema.ListToolsResult listTools(String cursor) {
       return getMcpSyncClient().listTools(cursor);
    }

    public McpSchema.ListResourcesResult listResources(String cursor) {
       return getMcpSyncClient().listResources(cursor);
    }

    public McpSchema.ListResourcesResult listResources() {
       return getMcpSyncClient().listResources();
    }

    public McpSchema.ReadResourceResult readResource(McpSchema.Resource resource) {
       return getMcpSyncClient().readResource(resource);
    }

    public McpSchema.ReadResourceResult readResource(McpSchema.ReadResourceRequest readResourceRequest) {
       return getMcpSyncClient().readResource(readResourceRequest);
    }

    public McpSchema.ListResourceTemplatesResult listResourceTemplates(String cursor) {
       return getMcpSyncClient().listResourceTemplates(cursor);
    }

    public McpSchema.ListResourceTemplatesResult listResourceTemplates() {
       return getMcpSyncClient().listResourceTemplates();
    }

    public void subscribeResource(McpSchema.SubscribeRequest subscribeRequest) {
       for (McpSyncClient mcpSyncClient : mcpSyncClientList) {
          mcpSyncClient.subscribeResource(subscribeRequest);
       }
    }

    public void unsubscribeResource(McpSchema.UnsubscribeRequest unsubscribeRequest) {
       for (McpSyncClient mcpSyncClient : mcpSyncClientList) {
          mcpSyncClient.unsubscribeResource(unsubscribeRequest);
       }
    }

    public McpSchema.ListPromptsResult listPrompts(String cursor) {
       return getMcpSyncClient().listPrompts(cursor);
    }

    public McpSchema.ListPromptsResult listPrompts() {
       return getMcpSyncClient().listPrompts();
    }

    public McpSchema.GetPromptResult getPrompt(McpSchema.GetPromptRequest getPromptRequest) {
       return getMcpSyncClient().getPrompt(getPromptRequest);
    }

    public void setLoggingLevel(McpSchema.LoggingLevel loggingLevel) {
       for (McpSyncClient mcpSyncClient : mcpSyncClientList) {
          mcpSyncClient.setLoggingLevel(loggingLevel);
       }
    }

    // ------------------------------------------------------------------------------------------------------------------------------------------------

    @Override
    public void onEvent(Event event) {
       if (event instanceof NamingEvent namingEvent) {
          if (this.serviceName.equals(namingEvent.getServiceName())) {
             _logger_.info("Received service instance change event for service: {}", namingEvent.getServiceName());
             List<Instance> instances = namingEvent.getInstances();
             _logger_.info("Updated instances count: {}", instances.size());
             // 打印每个实例的详细信息
             instances.forEach(instance -> {
                _logger_.info("Instance: {}:{} (Healthy: {}, Enabled: {}, Metadata: {})", instance.getIp(),
                      instance.getPort(), instance.isHealthy(), instance.isEnabled(),
                      JacksonUtils._toJson_(instance.getMetadata()));
             });
             updateClientList(instances);
          }
       }
    }

    private void updateClientList(List<Instance> currentInstances) {
       McpClientCommonProperties commonProperties = ApplicationContextHolder._getBean_(McpClientCommonProperties.class);
       McpSyncClientConfigurer mcpSyncClientConfigurer = ApplicationContextHolder
          ._getBean_(McpSyncClientConfigurer.class);
       ObjectMapper objectMapper = ApplicationContextHolder._getBean_(ObjectMapper.class);
       WebClient.Builder webClientBuilderTemplate = ApplicationContextHolder._getBean_(WebClient.Builder.class);

       // 移除的实例列表
       List<Instance> removeInstances = instances.stream()
          .filter(instance -> !currentInstances.contains(instance))
          .collect(Collectors._toList_());

       // 新增的实例列表
       List<Instance> addInstances = currentInstances.stream()
          .filter(instance -> !instances.contains(instance))
          .collect(Collectors._toList_());

       // 删除McpSyncClient实例
       List<String> clientInfoNames = removeInstances.stream()
          .map(instance -> connectedClientName(commonProperties.getName(),
                this.serviceName + "-" + instance.getInstanceId()))
          .toList();
       Iterator<McpSyncClient> iterator = mcpSyncClientList.iterator();
       while (iterator.hasNext()) {
          McpSyncClient mcpSyncClient = iterator.next();
          McpSchema.Implementation clientInfo = mcpSyncClient.getClientInfo();
          if (clientInfoNames.contains(clientInfo.name())) {
             _logger_.info("Removing McpsyncClient: {}", clientInfo.name());
             if (mcpSyncClient.closeGracefully()) {
                iterator.remove();
             }
             else {
                _logger_.warn("Failed to remove mcpSyncClient: {}", clientInfo.name());
             }
          }
       }

       // 新增McpSyncClient实例
       McpSyncClient syncClient;
       for (Instance instance : addInstances) {
          String baseUrl = instance.getMetadata().getOrDefault("scheme", "http") + "://" + instance.getIp() + ":"
                + instance.getPort();
          WebClient.Builder webClientBuilder = webClientBuilderTemplate.clone().baseUrl(baseUrl);
          WebFluxSseClientTransport transport = new WebFluxSseClientTransport(webClientBuilder, objectMapper);
          NamedClientMcpTransport namedTransport = new NamedClientMcpTransport(
                serviceName + "-" + instance.getInstanceId(), transport);

          McpSchema.Implementation clientInfo = new McpSchema.Implementation(
                this.connectedClientName(commonProperties.getName(), namedTransport.name()),
                commonProperties.getVersion());
          McpClient.SyncSpec syncSpec = McpClient._sync_(namedTransport.transport())
             .clientInfo(clientInfo)
             .requestTimeout(commonProperties.getRequestTimeout());
          syncSpec = mcpSyncClientConfigurer.configure(namedTransport.name(), syncSpec);
          syncClient = syncSpec.build();
          if (commonProperties.isInitialized()) {
             syncClient.initialize();
          }

          _logger_.info("Added McpAsyncClient: {}", clientInfo.name());
          mcpSyncClientList.add(syncClient);
       }

       this.instances = currentInstances;
    }

    private String connectedClientName(String clientName, String serverConnectionName) {
       return clientName + " - " + serverConnectionName;
    }

    public static Builder builder() {
       return new Builder();
    }

    public static class Builder {

       private String serviceName;

       private List<McpSyncClient> mcpSyncClientList;

       private NamingService namingService;

       public Builder serviceName(String serviceName) {
          this.serviceName = serviceName;
          return this;
       }

       public Builder mcpSyncClientList(List<McpSyncClient> mcpSyncClientList) {
          this.mcpSyncClientList = mcpSyncClientList;
          return this;
       }

       public Builder namingService(NamingService namingService) {
          this.namingService = namingService;
          return this;
       }

       public LoadbalancedMcpSyncClient build() {
          return new LoadbalancedMcpSyncClient(this.serviceName, this.mcpSyncClientList, this.namingService);
       }

    }

}

工具类

ApplicationContextHolder

复制代码 
@Component
public class ApplicationContextHolder implements ApplicationContextAware {

    private static ApplicationContext _applicationContext_;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
       ApplicationContextHolder._applicationContext _= applicationContext;
    }

    public static <T> T getBean(Class<T> clazz) {
       return _applicationContext_.getBean(clazz);
    }

}

效果演示

我在 nacos 中，注册了 MCP Server 服务，部署两个节点

  • 同一台机器以不同端口号启动的 MCP Server 服务，分别是 19000、19001，注册在 Nacos 中以 mcp-server-provider 为服务名

yml 配置如下

复制代码 
server:
  port: 8080

spring:
  application:
    name: mcp-client-webflux

_  _ai:
    alibaba:
      mcp:
        nacos:
          enabled: true
          server-addr: 127.0.0.1:8848
          username: nacos
          password: nacos
          
        client:
          sse:
            connections:
              nacos-server1: mcp-server-provider
              
    mcp:
      client:
        enabled: true
        name: mcp-client-webflux
        version: 0.0.1
        initialized: true
        request-timeout: 600s
    
        nacos-enabled: true

我们能发现已经成功注入 LoadbalancedMcpSyncClient 类，其中 mcp-server-provider 有两个实例，对应的两个 McpSyncClient

我们停掉其中的 MCP Server19001 端口的服务，通过 removeInstances 获取移除的实例列表，同步在 mcpSyncClientList 移除对应的 McpSyncClient

我们再新启动 MCP Server19001 端口的服务，通过 addInstances 获取新增的实例列表，同步在 mcpSyncClientList 新增对应的 McpSyncClient

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