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Comment by jimmyl02 | Hacker News Reader

This seems like a similar and more feature complete / polished version of JSON RPC?

The part that's most exciting to me is actually the bidirectional calling. Having set this up before via JSON RPC / custom protocol the experience was super "messy" and I'm looking forward to a framework making it all better.

Can't wait to try it out!

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Yeah, JSON RPC doesn't support the pass-by-reference and lifecycle management stuff. You just have a static list of top-level functions you can call. This makes a pretty big difference in what kinds of APIs you can express.

OTOH, JSON RPC is extremely simple. Cap'n Web is a relatively complicated and subtle underlying protocol.

> You just have a static list of top-level functions you can call.

Actually the author of JSON RPC suggested that method names could be dynamic, there's nothing in the spec preventing that.

https://groups.google.com/g/json-rpc/c/vOFAhPs_Caw/m/QYdeSp0...

So you could definitely build a cursed object/reference system by packing stuff into method names if you wanted. I doubt any implementations would allow this.

But yes, JSON RPC is very minimal and doesn't really offer much.

Right, your methods in JSON RPC could be dynamic. JSON RPC really doesn't specify anything, so you can do anything with it. But you need conventions around that, like how does a client find out that the server exported new methods, and how does the client indicate that it is done with them? That's exactly what Cap'n Web is all about -- defining those conventions in a usable way.

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