1193: disconnect event, connectivity errors

[rekmarks]

File: https://github.com/rekmarks/EIPs/blob/1193-open/EIPS/eip-1193.md

• Adds the disconnect event, intended to:
  • supersede the close event
  • make it clear that it's the counterpart of the connect event
• Deprecates the close event

The above follows discussions with @ryanio

In addition:

• Adds the following Provider errors:
  • 4900: Not Connected
  • 4901: Chain Not Connected
• Adds the section Connectivity for defining "connected" and "disconnected"

This allows consumers to tell whether their requests are failing because the Provider is disconnected.

[adrianmcli]

As much as I like the fact that open and close are symmetric. I think connect and disconnect makes a lot more intuitive sense and reflects what's actually happening. When I hear provider.open, my next question is "open what?".

[rekmarks]

The only reason I picked open was because the close event uses the Web API CloseEvent status codes, but that's not really striking me as that relevant, on consideration. I'll change it.

[eip-automerger]

Hi! I'm a bot, and I wanted to automerge your PR, but couldn't because of the following issue(s):

• EIP 1193 requires approval from one of (@MaiaVictor, @frozeman, @marcgarreau, @ryanio)

[rekmarks]

@ryanio, note that I added the isConnected method; please see description for justification.

Happy to roll it back if undesired, but, I obviously think it's justified 😛

[ryanio]

I’d prefer not to introduce another method. Wouldn’t you be able to just send a json rpc request like eth_chainId to verify connection?

[rekmarks]

I’m very sympathetic to that goal. eth_chainId is unfortunately of no help, because EIP 695 has nothing to say about the case where no chain ID is available.

On reflection, even though a method enabling consumers to tell if “the wire is hot” would be nice, we could just standardize this by means of an RPC error.

Since this will be specific to the Provider, that error should IMO be introduced here. What do you think?

[rekmarks]

e0e52a3 Removed isConnected, added connectivity errors.

[ryanio]

Really nice contributions, thanks very much 🎉