Improve RPC selection logic

[wottpal]

Currently, the RPC selection is too simple. It picks the first item in the rpcUrls array of a SubstrateChain (see https://github.com/scio-labs/use-inkathon/blob/main/src/provider.tsx#L82) and creates a WsProvider object (which even fails if the provided url is not a websocket).

• It must be determined whether it's a wss/https rpc url (e.g. via regex) and create the according provider object
• If an RPC connection fails multiple times it should try the next rpc (until the first one works). Otherwise, providing a full list of RPCs somehow makes no sense.

[niklasp]

+1

[peetzweg]

Not sure how good this applies here but a nice detail pjs apps does, is randomizing rpc endpoints. It's a nice detail to prevent overloading a single rpc and centralization through a single rpc provider.

Screen.Recording.2024-02-15.at.10.43.51.mov

[niklasp]

WsProvider accepts a string array of endpoints in the constructor as well as autoConnectMs: number

https://github.com/polkadot-js/api/blob/329929236846364e9feb316462ee300a1dc42608/packages/rpc-provider/src/ws/index.ts#L111

[wottpal]

The only problem I see with passing an array of strings to the WsProvider is that this would still not accompany for a given mixed set of https:// & wss:// endpoints. But I would be fine with having this implemented (after filtering the strings) as suggested … but have also never tried this approach and don't know how well this is handled by polkadot.js internally. Anyone? cc @peetzweg

[peetzweg]

When I had this issue described in #73 I've searched the parameters and docs of pjs but I wasn't able to find a feature like this. I know that pjs tries to reconnect if the connection drops or attempts to initialize it again, however it does not offer a way to specify more than a single provider.