如何在Tornado中创建几个websocket聊天？

Question

我正在尝试使用几个聊天创建一个Tornado应用程序.聊天应该基于HTML5 websocket.Websockets很好地沟通,但我总是遇到每个消息被发布两次的问题.

该应用程序使用四个类来处理聊天:

• Chat包含到目前为止的所有书面消息以及包含所有waiters应通知的列表

• ChatPool用作新Websockets的查找 - 当没有需要的人scratch_id或返回现有的聊天实例时,它会创建一个新的聊天.

• ScratchHandler 是所有HTTP请求的入口点 - 它解析基本模板并返回客户端的所有详细信息.

• ScratchWebSocket 查询数据库以获取用户信息,设置连接并通知聊天实例是否必须传播新消息.

如何防止多次发布消息？如何使用龙卷风构建多聊天应用程序？

import uuid
import tornado.websocket
import tornado.web
import tornado.template

from site import models
from site.handler import auth_handler

class ChatPool(object):

    # contains all chats

    chats = {}

    @classmethod
    def get_or_create(cls, scratch_id):

        if scratch_id in cls.chats:
            return cls.chats[scratch_id]
        else:
            chat = Chat(scratch_id)
            cls.chats[scratch_id] = chat
            return chat


    @classmethod
    def remove_chat(cls, chat_id):

        if chat_id not in cls.chats: return
        del(cls.chats[chat_id])


class Chat(object):

    def __init__(self, scratch_id):

        self.scratch_id = scratch_id
        self.messages = []
        self.waiters = []

    def add_websocket(self, websocket):
        self.waiters.append(websocket)

    def send_updates(self, messages, sending_websocket):
        print "WAITERS", self.waiters   
        for waiter in self.waiters:
            waiter.write_message(messages)
        self.messages.append(messages)


class ScratchHandler(auth_handler.BaseHandler):

    @tornado.web.authenticated
    def get(self, scratch_id):

        chat = ChatPool.get_or_create(scratch_id)
        return self.render('scratch.html', messages=chat.messages,
                                           scratch_id=scratch_id)


class ScratchWebSocket(tornado.websocket.WebSocketHandler):

    def allow_draft76(self):
        # for iOS 5.0 Safari
        return True

    def open(self, scratch_id):

        self.scratch_id = scratch_id
        scratch = models.Scratch.objects.get(scratch_id=scratch_id)

        if not scratch:
            self.set_status(404)
            return

        self.scratch_id = scratch.scratch_id

        self.title = scratch.title
        self.description = scratch.description
        self.user = scratch.user

        self.chat = ChatPool.get_or_create(scratch_id)
        self.chat.add_websocket(self)        

    def on_close(self):
        # this is buggy - only remove the websocket from the chat.
        ChatPool.remove_chat(self.scratch_id)

    def on_message(self, message):
        print 'I got a message'
        parsed = tornado.escape.json_decode(message)
        chat = {
            "id": str(uuid.uuid4()),
            "body": parsed["body"],
            "from": self.user,
            }

        chat["html"] = tornado.escape.to_basestring(self.render_string("chat-message.html", message=chat))
        self.chat.send_updates(chat, self)

注意:在@A的反馈之后.杰西我改变了send_updates方法Chat.不幸的是,它仍然返回双倍值.

class Chat(object):

    def __init__(self, scratch_id):

        self.scratch_id = scratch_id
        self.messages = []
        self.waiters = []

    def add_websocket(self, websocket):
        self.waiters.append(websocket)

    def send_updates(self, messages, sending_websocket):

        for waiter in self.waiters:
            if waiter == sending_websocket:
                continue
            waiter.write_message(messages)

         self.messages.append(messages)

2.EDIT:我将我的代码与示例提供的演示进行了比较.在websocket示例中,通过WebSocketHandler子类和类方法将新消息传播给服务员.在我的代码中,它是由一个分离的对象完成的:

来自演示:

class ChatSocketHandler(tornado.websocket.WebSocketHandler):

    @classmethod
    def send_updates(cls, chat):
        logging.info("sending message to %d waiters", len(cls.waiters))

        for waiter in cls.waiters:
            try:
                waiter.write_message(chat)
            except:
                logging.error("Error sending message", exc_info=True)

我的应用程序使用一个对象而没有WebSocketHandler的子类

class Chat(object):

    def send_updates(self, messages, sending_websocket):

        for waiter in self.waiters:
            if waiter == sending_websocket:
                continue
            waiter.write_message(messages)

        self.messages.append(messages)

Answer 1

如果要创建基于Tornado的多聊天应用程序,我建议您使用某种消息队列来分发新消息.这样,您就可以在负载均衡器(如nginx)后面启动多个应用程序进程.否则,您将仅停留在一个进程中,因此在缩放方面受到严重限制.

我更新了我的旧Tornado聊天示例,以支持您要求的多房间聊天.看看存储库:

龙卷风Redis的聊天

现场演示

这个简单的Tornado应用程序使用Redis Pub/Sub功能和websockets将聊天消息分发给客户端.通过简单地使用聊天室ID作为发布/订阅频道来扩展多房间功能非常容易.