Question

我试图通过利用AWS的websocket api网关在网站上的用户之间实现消息传递。我看到的每个指南/文档都说要使用wscat来测试与网关的连接。我现在可以连接到api网关，并使用wscat在客户端之间发送消息，但是我很难从ts代码中以编程方式使其工作。

我想做的是，一旦用户登录，就对websocket api网关进行api调用，以便他们可以随时发送消息。我在后端使用无服务器，在前端使用Angular 6。我了解到我需要向POST发出https://{api-id}.execute-api.us-east-1.amazonaws.com/{stage}/@connections/{connection_id}请求，以通过Websocket连接发送消息，但是我在为连接/获取连接ID而创建的服务中使用打字稿遇到了麻烦。

在用户成功登录以打开与websocket api网关的连接之后，我正在进行第二次API调用。我尝试调用一个没有正文的发布请求的函数（不确定我将在请求正文中发送的内容，因为我仅使用wscat工具将其发送给它）部署了无服务器代码后获得的URL。在手动部署API网关之后，我还尝试过对在AWS控制台中看到的https：// URL发出POST请求。

base.service.ts

protected getBaseSocketEndpoint(): string {
        // 'wss://xxxxxxx.execute-api.us-east-1.amazonaws.com/dev' <-- tried this too
        return 'https://xxxxxxxx.execute-api.us-east-1.amazonaws.com/dev/@connections';
    }

authentication.service.ts

this.authService.login(username, password).pipe(first()).subscribe(
            (response) => {
                console.log(response);
                this.authService.setCookie('userId', response.idToken.payload.sub);
                this.authService.setCookie('jwtToken', response.idToken.jwtToken);
                this.authService.setCookie('userEmail', response.idToken.payload.email);
                this.authService.setCookie('refreshToken', response.refreshToken.token);

                this.toastr.success('Login successful. Redirecting to your dashboard.', 'Success!', {
                    timeOut: 1500
                });

                this.authService.connectToWebSocket(response.idToken.payload.sub).pipe(first()).subscribe(
                    response => {
                        console.log(response);
                    }
                );

                this.routerService.routeToUserDashboard();
            },
            (error) => {
                // const errorMessage = JSON.parse(error._body).message;
                this.toastr.error("Incorrect username and password combination.", 'Error!', {
                    timeOut: 1500
                });
            }
        );

authentication.service.ts扩展了BaseService

public connectToWebSocket(userId: string): Observable<any> {
        const body = {
            userId: userId
        };

        console.log('calling connectToWebSocket()..');
        return this.http.post(this.getBaseSocketEndpoint(), body).pipe(map(response => {
            console.log(response);
        }));
    }

serverless.yaml

functions:
  connectionHandler:
    handler: connectionHandler.connectionHandler
    events:
      - websocket:
          route: $connect
          cors: true
      - websocket:
          route: $disconnect
          cors: true
  defaultHandler:
    handler: connectionHandler.defaultHandler
    events:
      - websocket:
          route: $default
          cors: true
  sendMessageHandler:
    handler: messageHandler.sendMessageHandler
    events:
      - websocket:
          route: sendMessage
          cors: true

connectionHandler.js（lambda）

const success = {
  statusCode: 200,
  headers: { "Access-Control-Allow-Origin": "*" },
  body: "everything is alright"
};

module.exports.connectionHandler = (event, context, callback) => {
  var connectionId = event.requestContext.connectionId;
  if (event.requestContext.eventType === "CONNECT") {
    addConnection(
      connectionId,
      "b72656eb-db8e-4f32-a6b5-bde4943109ef",
      callback
    )
      .then(() => {
        console.log("Connected!");
        callback(null, success);
      })
      .catch(err => {
        callback(null, JSON.stringify(err));
      });
  } else if (event.requestContext.eventType === "DISCONNECT") {
    deleteConnection(
      connectionId,
      "b72656eb-db8e-4f32-a6b5-bde4943109ef",
      callback
    )
      .then(() => {
        console.log("Disconnected!");
        callback(null, success);
      })
      .catch(err => {
        callback(null, {
          statusCode: 500,
          body: "Failed to connect: " + JSON.stringify(err)
        });
      });
  }
};

// THIS ONE DOESNT DO ANYHTING
module.exports.defaultHandler = (event, context, callback) => {
  callback(null, {
    statusCode: 200,
    body: "default handler was called."
  });
};

const addConnection = (connectionId, userId, callback) => {
  const params = {
    TableName: CHATCONNECTION_TABLE,
    Item: {
      connectionId: connectionId,
      userId: userId
    }
  };

  var response;
  return dynamo
    .put(params, function(err, data) {
      if (err) {
        errorHandler.respond(err, callback);
        return;
      } else {
        response = {
          statusCode: 200,
          headers: { "Access-Control-Allow-Origin": "*" },
          body: JSON.stringify(data)
        };
        callback(null, response);
      }
    })
    .promise();
};

const deleteConnection = (connectionId, userId, callback) => {
  const params = {
    TableName: CHATCONNECTION_TABLE,
    Key: {
      connectionId: connectionId,
      userId: userId
    }
  };

  var response;
  return dynamo
    .delete(params, function(err, data) {
      if (err) {
        errorHandler.respond(err, callback);
        return;
      } else {
        response = {
          statusCode: 200,
          headers: { "Access-Control-Allow-Origin": "*" },
          body: JSON.stringify(data)
        };
        callback(null, response);
      }
    })
    .promise();
};

预期：触发POST api调用并打开与Websocket API网关的持久连接。

实际：无法通过上述API调用进行连接。我在控制台中收到403，并显示以下消息：

从原点“ https://xxxxxxx.execute-api.us-east-1.amazonaws.com/dev/@connections”到“ http://localhost:4200”处对XMLHttpRequest的访问已被CORS策略阻止：对预检请求的响应未通过访问控制检查：否'Access-Control-Allow-来源的标头出现在请求的资源上。

不确定在无服务器文件中启用CORS时为什么会出现CORS错误。

Answer 1

我遇到了同样的问题，最后弄清楚，通常在websockets中不应出现这样的CORS错误消息：

Why is there no same-origin policy for WebSockets? Why can I connect to ws://localhost?

跳过客户端库“ socket.io”并使用“ vanilla websockets”帮助了我。

在您的情况下，我将检查“ connectToWebSocket”后面的库。

Answer 2

我有类似的问题。您可以使用所有socket.io-client优点。但是您必须将选项传输设置为：

 let socket = io(url, {
        reconnectionDelayMax: 1000,
        transports: ["websocket"],
      });

默认值为

transports: ["polling", "websocket"],

因此，您的应用将开始轮询，并导致CORS错误。在文档中尚不清楚，但是这里是useful link。

在“基础Engine.IO客户端的可用选项：”下查看。

Answer 3

我使用了python lambda处理程序，因此它可能对很多人有帮助。
我已经实现了一个Websocket，可以向用户发送5次带有间隔的消息
serverless.yml

service: realtime-websocket-test

provider:
  name: aws
  stage: ${opt:stage, 'dev'}
  runtime: python3.8
  region: ${opt:region, 'ap-south-1'}
  memorySize: 128
  timeout: 300

functions:
  connect:
    handler: handler.lambda_handler
    events:
      - websocket:
          route: $connect
      - websocket:
          route: $disconnect
      - websocket:
          route: $default

handler.py

import time
import json
import boto3


def lambda_handler(event, context):
    print(event)
    event_type = event["requestContext"]["eventType"]

    if event_type == "CONNECT" or event_type == "DISCONNECT":
        response = {'statusCode': 200}
        return response     
    
    elif event_type == "MESSAGE":   
        connection_id = event["requestContext"]["connectionId"]
        domain_name = event["requestContext"]["domainName"]
        stage = event["requestContext"]["stage"]

        message = f'{domain_name}: {connection_id}'.encode('utf-8')
        api_client = boto3.client('apigatewaymanagementapi', endpoint_url = f"https://{domain_name}/{stage}")

        for _ in range(5):
            api_client.post_to_connection(Data=message,
                                                ConnectionId=connection_id)
            time.sleep(5)

    
        response = {'statusCode': 200}
        return response

如何以编程方式连接到AWS Websocket API网关

3 个答案: