Comment by sudhirj | Hacker News Reader

Comment by sudhirj | Hacker News Reader

Parent Full thread

The simplest example is liveblogging - someone is sitting at the next iPhone launch, and sending out photos and commentary that's being updated as they send on a large number of readers' screens worldwide. The Verge has a good system that they do with polling S3 for new data, but there's really much more effective ways to do it.

The more specific cases include opening ticket sales for movies in India - for some big movies tickets are sold out really quickly, so there'll be hundreds or thousands of people with browsers / phones open on a seat layout and they all need to see which seats are being sold in real-time.

Then there's broadcasting stock market movements and tips to thousands of traders in real-time.

The only existing solutions that seem really scalable are fanout.io - others like pusher.com and pubnub.com have pricing that's not conducive to serving a large number of simultaneous users / broadcasting. Fanout.io gets this right, but would be nice to have cheaper alternatives / make it a commodity.

Given that the CF nodes do support websockets, I assume they terminate and re-create new connections to origins as well - so the nodes are capable of holding a large number of websockets open, right? Can Workers intercept websockets / stream data into them? And given that the KV store is capable of propagating new values to all the nodes, there could be a way expose incoming change notifications on keys, which would handle this use case. Could also implement as continuous addition of new timestamps keys, prefixed with a topic.

Fundamentally what I think we want to do is build the primitives you would need to create your own fanout. That means we need the ability to push events to Worker nodes, and for Workers to be able to terminate WebSockets for you.

If you can accept up to 10s of latency, I agree that KV could solve the 'pushing events' problem for you. (A tuple store is semantically equivalent to message passing, and it will get easier when we support range queries).

Yes, both points make sense. And I assume the 10s latency is also geographically related - i.e. it's worst case 10s for the longest distance on the network topology graph? That should be fine.

Low latency requirements also tend to be geographical, I think - stock markets are mostly specific to a single country, examples like ticketing are usually specific to a single city / edge. For general news being broadcast globally, that kind of latency is fine.

> Fanout.io gets this right, but would be nice to have cheaper alternatives / make it a commodity.

Hi! Fanout founder here. I’m glad you like our way of doing things. If you need better pricing for high volume we are always willing to discuss.

I’m not sure you’d want to maintain a WebSocket inside of a CF worker. At least I can’t see that helping with cost. Execution time limits would get you too. IMO connection management belongs as a separate layer in front of the worker, so workers are only woken when things happen.

And on that note, of course you can use Fanout together with Cloudflare Workers today. At the moment this requires making raw API calls but we plan to update our server libs for CF compatibility soon.

> Hi! Fanout founder here. I’m glad you like our way of doing things. If you need better pricing for high volume we are always willing to discuss.

Hi! Wasn't expecting you to show up like this. Re. pricing for high volume, I'm sure enterprises and publishers could afford it, I'm trying to see if it's possible to offer free or very cheap service to individuals with large audiences. So not so much that I want a high volume discount, I'm trying to figure out a way to make it one or two orders of magnitude cheaper, enough that pricing is no longer relevant. Self hosting Pushpin is an option, but CF might be easier to work with.

> I’m not sure you’d want to maintain a WebSocket inside of a CF worker. At least I can’t see that helping with cost. Execution time limits would get you too.

The CF edges already hold / passthrough websockets - whether the Workers API is conducive to controlling them is the question, but we know it already allows streaming - doesn't seem like big jump from there. And for my purposes one-way streaming is enough, so might not even need to change the API. And based on the current billing model it seems like only CPU time is billed (?) - so if the socket is waiting most of the time it's still cost effective. And connection management itself would still be outside the scope of the worker - I'm saying the worker's event loop should behave exactly the way it would if I using the streaming feature right now to make a 1000 slow network requests from the worker and streamed the responses out as the worker received them. Only the protocol would change.

I actually have an open PR to add WebSocket endpoint support to CF Workers (so a Worker can act as a WebSocket client or server, instead of just a proxy). The main hangup though is that we need to figure out how to charge for long-lived connections. We obviously don't want to apply the normal time limits in this case. Hopefully we'll find time to work through this soon. :)

Nice! My 2 cents would be to charge a cheap rate for idling time and the regular rate for CPU execution. Or maybe use bandwidth as a proxy for CPU usage and an overall connection time charge.

Oh interesting, I didn't realize CF Workers metered by actual CPU usage and not just clock time. That would certainly make a difference in the expected cost.

Even still, handling millions of simultaneous connections, with each connection in its own worker in a multi-tenant execution environment in order to save money sounds crazy. :) The operating cost (and thus the price) of a purpose-built system like ours should be lower than that of a generalized system. I think your easiest path is to just tell us your preferred pricing model.

Depends on how you look at it. The way I see it I would be quite reasonable to start a few droplets / instances in every region Digital Ocean / AWS support and have websockets terminate there. I'd could even assume this is what Fanout/comparable service is currently doing.

From the cloudflare side I'd assume that each edge has 1 > n <= 10 of the CF version of this https://www.top-ix.org/wp-content/uploads/2016/10/Open-Conne... . Imagine CF had 100s to 1000s of these at every edge - they could/would then offer either DO sized droplets or AWS Fargate sized containers at every edge with CF load balancing, and we could be installing Pushpin on every edge. And it wouldn't sound odd. This seems like it's just a logistics problem - it's not inconceivable that 2020 / 2023 birthday week will announce this. (@CF you should totally call each droplet/instance a 'Flare')

In the meantime the Workers seems like a way to offer highly controlled computing on these edges - but other than the tighter control of the executing environment I see no difference from the scenario mentioned above. So if all the load balancing, connection handling and deployment pieces are already in place, I think we can and should try to use it for any possible use case that we would have used regular servers for.

To me there's a big difference between a compute host (VM/containers) and a function host in this context.

Running Pushpin on a bunch of compute instances means being able to operate at maximum performance with minimal impact between tenants. Compared to FaaS, I believe the difference in resource usage should be so significant that any provider of a shared-Pushpin service would be able to win on price.

I'm also still not quite sure how a FaaS-based push system would actually work since there's the problem of getting data around among the workers. You don't want a million workers polling a DB. I suppose you could integrate a messaging/queuing system with your workers, and each worker keeps a long-lived connection with the queuing system. But if you do this, you'll have barely built a push system at all. Instead you'll be dependent upon a millions-connection-capable queuing system, and your workers will simply be doing data conversion between two connections. And of course the queuing system would live outside of the FaaS, provided by someone for a cost.

It's worth realizing the multi-tenant nature of Workers happens within a single process, meaning from a cost perspective it's essentially indistinguishable from running your own hardware. It's actually one _less_ VM than if you were managing your own EC2 instances.

Reply on news.ycombinator.com