Does Cap'n Web support Websocket Hibernation

[natanparmigiano-paganinitech]

Hello!

First of all, amazing work, we are considering switching out tRPC for Cap'n Web for our next projects!

But an important question was raised internally:

When using Websockets in CF Workers, does Cap'n Web handle websocket hibernation by default?

Is there any example on how to implement hibernation (with DO) together with Cap'n Web?

[kentonv]

At this time, it does not. But this is definitely something we want to fix!

[kentonv]

To add a bit of detail here, I don't think the solution is for Cap'n Web itself to try to support hibernation, but rather for us to extend the way hibernation works in the Workers Runtime, so that RPC stubs are hibernatable. What you'd do then is use Cap'n Web between a browser and a stateless worker, which in turn uses Workers built-in RPC from there to the DO. Workers RPC would then need to support hibernating RpcTargets and storing stubs through hibernation.

[Sillyvan]

Just looked this up and wondered if i could use Cap'n'Web to basically get a typed WS between the client and my DO with hibernation.

Also saw this #110

Do i understand correctly that:
You can pass a DO as your "RPC Target"
But no matter what you would not get ws hibernation?

[kentonv]

Not sure I exactly understand the question.

However: Holding a DO stub does not prevent hibernation. So if, in your stateless routing worker, you return the DO stub itself to the client over Cap'n Web, that in itself shouldn't prevent hibernation. It's only while calls are active that it won't be able to hibernate. Or if you hold stubs pointing at functions or RpcTarget objects in the DO's isolate.