阿波罗联邦订阅是Apollo GraphQL的一种特殊订阅方式，可以用于实现实时数据的订阅和推送。下面是一个在Node.js 8.11.1上实现阿波罗联邦订阅的示例代码：

1. 首先，安装Apollo Server和相关依赖：

npm install apollo-server graphql graphql-subscriptions subscriptions-transport-ws

2. 创建一个GraphQL服务器，并在其中启用阿波罗联邦订阅：

const { ApolloServer, gql } = require("apollo-server");
const { PubSub } = require("graphql-subscriptions");
const { execute, subscribe } = require("graphql");
const { createServer } = require("http");
const { SubscriptionServer } = require("subscriptions-transport-ws");

// 定义GraphQL类型和Resolvers
const typeDefs = gql`
  type Query {
    hello: String
  }

  type Mutation {
    publishMessage(message: String!): String
  }

  type Subscription {
    messagePublished: String
  }
`;

const resolvers = {
  Query: {
    hello: () => "Hello, world!"
  },
  Mutation: {
    publishMessage: (_, { message }, { pubsub }) => {
      pubsub.publish("MESSAGE_PUBLISHED", { messagePublished: message });
      return message;
    }
  },
  Subscription: {
    messagePublished: {
      subscribe: (_, __, { pubsub }) => pubsub.asyncIterator("MESSAGE_PUBLISHED")
    }
  }
};

// 创建PubSub实例
const pubsub = new PubSub();

// 创建Apollo Server
const server = new ApolloServer({
  typeDefs,
  resolvers,
  context: { pubsub }
});

// 创建HTTP服务器
const httpServer = createServer();
server.applyMiddleware({ app: httpServer });

// 启动HTTP服务器
httpServer.listen({ port: 4000 }, () => {
  console.log(`Server ready at http://localhost:4000${server.graphqlPath}`);
});

// 创建Subscription服务器
const subscriptionServer = SubscriptionServer.create(
  {
    schema: server.schema,
    execute,
    subscribe
  },
  {
    server: httpServer,
    path: server.graphqlPath
  }
);

console.log(`Subscription server ready at ws://localhost:4000${server.graphqlPath}`);

3. 运行代码：

node server.js

现在，你可以使用GraphQL客户端来订阅messagePublished事件并接收实时推送的消息。例如，使用Apollo Client进行订阅：

import { ApolloClient, InMemoryCache, gql } from "@apollo/client";
import { WebSocketLink } from "@apollo/client/link/ws";

const client = new ApolloClient({
  link: new WebSocketLink({
    uri: "ws://localhost:4000/graphql",
    options: {
      reconnect: true
    }
  }),
  cache: new InMemoryCache()
});

const subscription = client.subscribe({
  query: gql`
    subscription {
      messagePublished
    }
  `
});

subscription.subscribe({
  next: ({ data }) => console.log("Received new message:", data.messagePublished)
});

这样，当你在Mutation中发布一条消息时，订阅会立即收到推送的消息。