Microsoft Bot Builder中TurnContext在WebSocket监听内触发代理撤销错误

我想把WebSocket服务器返回的响应展示在Microsoft Bot Builder模拟器里，但在ws.addEventListener监听函数里遇到了问题。调试发现调用await turnContext.sendActivity(responseMessage)时，TurnContext丢失了作用域，没法向模拟器返回响应。控制台能收到WebSocket的响应，但触发了如下错误：

responseMessage :- BOT : To speak to an agent, press or say #
Insise Error
TypeError: Cannot perform 'get' on a proxy that has been revoked
at WebSocket. (D:\azure-bot\echo-bot\bots\stateManagementBot.js:155:59)

相关代码片段 #

ws.addEventListener('message',async function (event) {
    const msg = JSON.parse(event.data);
    if(msg.topic === 'aws/chat' && msg.contentType === 'application/json'){
        const content = JSON.parse(msg.content);
        switch(content.Type){
            case 'MESSAGE':
                try{
                      if(content.ParticipantRole !== 'CUSTOMER'){
                        responseMessage = `${content.DisplayName} : ${content.Content}`;
                        console.log(`responseMessage :- ${responseMessage}`);
                        await turnContext.sendActivity(responseMessage);
                    }
                }catch(error){
                    console.log("Insise Error");
                    console.log(error);
                }
                break;
            case 'Event':
                if(content.ContentType.includes('ended')){
                    responseMessage = `Chat ended`;
                }
        }
    }
});

完整代码片段 #

// The accessor names for the conversation data and user profile state property accessors.
const CONVERSATION_DATA_PROPERTY = 'conversationData';
const USER_PROFILE_PROPERTY = 'userProfile';

let responseMessage;
let connectionToken;
let ws;

class StateManagementBot extends ActivityHandler {
    constructor(conversationState, userState) {
        super();
    // Create the state property accessors for the conversation data and user profile.
    this.conversationDataAccessor = conversationState.createProperty(CONVERSATION_DATA_PROPERTY);
    this.userProfileAccessor = userState.createProperty(USER_PROFILE_PROPERTY);

    // The state management objects for the conversation and user state.
    this.conversationState = conversationState;
    this.userState = userState;

    this.onMessage(async (turnContext, next) => {
        // Get the state properties from the turn context.
        // By calling next() you ensure that the next BotHandler is run.await next()
        
        if(turnContext.activity.text === '#'){
            const url = await this.connectToAgent(turnContext.activity.text);
            const initialMessage = {
                topic: "aws/subscribe",
                content: {
                topics: ["aws/chat"]
                }
            };
            console.log(url[1]);
            ws = new WebSocket(url[1]);
            console.log('Before Websocket....');
            ws.addEventListener("open", () => {
                console.log('Websocket....');
                ws.send(JSON.stringify(initialMessage));
            });
            console.log("Websocket Conn...");
            const param = {
                ConnectionToken: connectionToken, /* required */
                Content: turnContext.activity.text, /* required */
                ContentType: 'text/plain', /* required */
            };
            connectparticipant.sendMessage(param, function(err, data) {
                console.log('Sending....');
                if (err) console.log(err, err.stack); // an error occurred
                else     console.log(data);           // successful response
            });

            ws.addEventListener('message',async function (event) {
                const msg = JSON.parse(event.data);
                if(msg.topic === 'aws/chat' && msg.contentType === 'application/json'){
                    const content = JSON.parse(msg.content);
                    switch(content.Type){
                        case 'MESSAGE':
                            try{
                                  if(content.ParticipantRole !== 'CUSTOMER'){
                                    responseMessage = `${content.DisplayName} : ${content.Content}`;
                                    console.log(`responseMessage :- ${responseMessage}`);
                                    await turnContext.sendActivity(responseMessage);
                                }
                            }catch(error){
                                console.log("Insise Error");
                                console.log(error);
                            }
                            break;
                        case 'Event':
                            if(content.ContentType.includes('ended')){
                                responseMessage = `Chat ended`;
                            }
                    }
                }
            });
            
        }
        // By calling next() you ensure that the next BotHandler is run.
        await next();
    });

解决方案 #

问题根源在于：TurnContext是当前消息处理周期的临时对象，周期结束后会被系统回收（代理被撤销）。而WebSocket的message事件是异步触发的，此时原TurnContext已经失效，无法再用来发送消息。需要通过保存对话引用，发起新的对话轮次来发送消息。

具体修改步骤： #

1. 在Bot类中添加必要属性
   修改构造函数，传入adapter引用，并创建Map存储WebSocket与对话引用的映射，避免全局变量污染和多用户冲突：

   class StateManagementBot extends ActivityHandler {
       constructor(conversationState, userState, adapter) {
           super();
           this.adapter = adapter; // 保存adapter实例
           this.activeConversations = new Map(); // 存储活跃对话的引用
           
           // 原构造函数中的其他代码
           this.conversationDataAccessor = conversationState.createProperty(CONVERSATION_DATA_PROPERTY);
           this.userProfileAccessor = userState.createProperty(USER_PROFILE_PROPERTY);
           this.conversationState = conversationState;
           this.userState = userState;
       }
   }
   

   注意：创建Bot实例时要传入adapter参数。

2. 保存对话引用
   在onMessage处理函数中，当用户发送#时，提取并保存对话引用：

   this.onMessage(async (turnContext, next) => {
       if(turnContext.activity.text === '#'){
           // ... 原有的WebSocket连接代码
           
           // 保存对话引用
           const conversationReference = TurnContext.getConversationReference(turnContext.activity);
           this.activeConversations.set(ws, conversationReference);
           
           // ... 其他代码
       }
       await next();
   });
   

3. 修改WebSocket消息回调
   在回调中使用保存的对话引用，通过adapter.continueConversation发起新的对话轮次来发送消息：

   ws.addEventListener('message', async (event) => {
       const msg = JSON.parse(event.data);
       if (msg.topic === 'aws/chat' && msg.contentType === 'application/json') {
           const content = JSON.parse(msg.content);
           switch (content.Type) {
               case 'MESSAGE':
                   try {
                       if (content.ParticipantRole !== 'CUSTOMER') {
                           const responseMessage = `${content.DisplayName} : ${content.Content}`;
                           console.log(`responseMessage :- ${responseMessage}`);
                           
                           // 获取保存的对话引用
                           const conversationReference = this.activeConversations.get(ws);
                           // 发起新的对话轮次发送消息
                           await this.adapter.continueConversation(conversationReference, async (newTurnContext) => {
                               await newTurnContext.sendActivity(responseMessage);
                           });
                       }
                   } catch (error) {
                       console.log("Inside Error");
                       console.log(error);
                   }
                   break;
               case 'Event':
                   if (content.ContentType.includes('ended')) {
                       const responseMessage = `Chat ended`;
                       const conversationReference = this.activeConversations.get(ws);
                       await this.adapter.continueConversation(conversationReference, async (newTurnContext) => {
                           await newTurnContext.sendActivity(responseMessage);
                       });
                       // 清理资源
                       this.activeConversations.delete(ws);
                       ws.close();
                   }
                   break;
           }
       }
   });
   

4. 清理全局变量
   将原代码中的全局变量ws、responseMessage、connectionToken改为类的属性，避免多用户场景下的冲突：

   class StateManagementBot extends ActivityHandler {
       constructor(conversationState, userState, adapter) {
           super();
           // ... 其他属性
           this.connectionToken = null;
       }
   }
   

内容的提问来源于stack exchange，提问作者Mohammed Tariq