Redis 客户端广播问题(在 Socket.IO 的上下文中) [英] Redis clients broadcast problems (in the context of Socket.IO)

问题描述

所以我阅读了一些关于扩展 Socket.IO 的文章.由于各种原因，我不想使用内置的 Socket.IO 缩放机制(主要是它似乎效率低下，因为它向 Redis 发布了更多的东西，然后从我的角度来看是必需的).

So I've read some articles about scaling Socket.IO. For various reasons I don't want to use built-in Socket.IO scaling mechanism (mostly it seems to be inefficient, since it publishes a lot more stuff to Redis then required from my point of view).

所以我想出了一个简单的想法:

So I've came up with this simple idea:

每个 Socket.IO 服务器创建 Redis 发布/订阅/存储客户端，连接到 Redis 并订阅频道.现在，当我想广播数据时，我只需将其发布到 Redis，所有其他 Socket.IO 服务器都会获取它并将其推送给用户.

Each Socket.IO server creates Redis pub/sub/store clients, connects to Redis and subscribes to a channel. Now, when I want to broadcast data I just publish it to Redis and all other Socket.IO servers get it and push it to users.

但是有一个问题(我认为这也是 Socket.IO 内置机制的问题).假设我想知道所有连接用户的数量.至少有两种方法可以做到这一点:

There is a problem, though (which I think is also a problem for Socket.IO built-in mechanism). Let's say I want to know the number of all connected users. There are at least two ways of doing that:

1. 服务器 A 将 give_me_clients 发布到 Redis.然后每个 Socket.IO 服务器计算连接数并发布 number_of_clients.服务器 A 获取这些数据，将其合并并发送给客户端.

1. Server A publishes give_me_clients to Redis. Then each Socket.IO server counts connections and publishes number_of_clients. Server A grabs this data, combines it and sends it to the client.

每当用户连接/断开服务器时，每个服务器都会更新 Redis 中的 number_of_clients_for::ID_HERE.然后服务器 A 只是获取数据并组合它.可能会更有效率.

Each server updates number_of_clients_for::ID_HERE in Redis whenever user connects/disconnects to the server. Then Server A just fetches data and combines it. Might be more efficient.

尽管这些解决方案存在问题:

There are problems with these solutions though:

1. 服务器 A 不知道其他服务器.因此他不知道什么时候应该停止监听number_of_clients.可以通过让服务器 A 了解其他服务器来解决这个问题:每当服务器连接到 Redis 时，他都会发布 new_server(服务器 A 获取数据并将其存储在内存中).但是，当 Redis - Socket.IO 连接中断时该怎么办?Redis 有没有办法通知客户端其中一个客户端断开连接?

1. Server A is not aware of other servers. Therefore he does not know when he should stop listening to number_of_clients. One could fix it with making Server A aware of other servers: whenever a server connects to Redis he publishes new_server (Server A grabs the data and stores it in memory). But what to do, when Redis - Socket.IO connection breaks? Is there a way for Redis to notify clients that one of the client disconnected?

其实和上面一样.当 Socket.IO 服务器崩溃时，如何清除 number_of_clients 数据?

Actually the same as above. When a Socket.IO server crashes how to clear number_of_clients data?

所以真正的问题是:Redis 能否通知(发布到 chanel)客户端与其中之一的连接刚刚结束??

So the real question is: can Redis notify (publish to chanel) clients that the connection with one of them has just ended??

推荐答案

经过大量测试，Redis 似乎没有这样的功能.我还发现，扩展 Socket.IO 真的很痛苦.

After a lot of testing it seems, that Redis does not have such functionality. Also I've found out, that scaling Socket.IO is really a pain.

所以我已经从 Socket.IO 切换到 WS(请参阅此链接).它是低级别的(但非常适合我使用)并且它只支持 WebSockets(在所有主要版本中).但话说回来，我只想支持 WebSockets 和 FlashSocket(我必须手动实现，但这很好).

So I've switched from Socket.IO to WS (see this link). It is low level (but perfect for my use) and it only supports WebSockets (in all major versions). But then again I only want to support WebSockets and FlashSocket (which I have to imlement manually, but that's fine).

优点是我可以轻松地使用此类服务​​器创建集群.HAProxy 几乎是开箱即用的(一些小的调整).服务器可以轻松地在本地网络上进行通信(如果集群很大，则使用 UDP 或中央 TCP 服务器).

The advantage is that I can easily create cluster with such servers. HAProxy works with such servers almost out of the box (some minor tuning). Servers can easily communicate on a local net (with UDP or central TCP server if the cluster is big).

缺点是必须手动实现一些很酷的功能，例如心跳、广播、房间等.您还需要长轮询回退，但对我来说这很好.恕我直言，缩放仍然更重要.

The disadvantage is that one have to manually implement some cool features like heartbeats, broadcasting, rooms, etc. Also you want have long-polling fallback, but that's fine in my case. Scaling is still more important, imho.

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