Eth JSON RPC: Support cancelation

[safareli]

Would be nice if sencAsync returned something like XMLHttpRequest object so once can abort the request (like XMLHttpRequest.abort()).

I guess this would be blocked until https://github.com/kumavis/json-rpc-engine/issues/4 is fixed

[kumavis]

this would be a change to the standard ethereum JSON-RPC spec, goes a bit beyond a feature request in metamask

what is your primary usecase and what sort of calls are you interested in canceling?

[safareli]

If you are referring to ethereum/wiki/JSON-RPC by "standard ethereum JSON-RPC spec" then I don't see how this request would result in change of that spec, can you clarify?

sencAsync at this moment is not returning any value. and I was proposing to to return underling XMLHttpRequest so one can .abort() that, if client is not interested in result of the call and free up enquired resources.

Exposing XMLHttpRequest might not be the best as transport layer might change or something, so some object with a cancel or abort method might be much better.

[safareli]

For reference this is was just merged in web3.js
web3/web3.js#1618

[danfinlay]

This would be something to add to the provider API, so now part of EIP-1193.

[danfinlay]

The simpler path to this is probably to add an RPC method for requesting the cancellation of a pending transaction, rather than modifying the provider interface.

Since a provider change is huge in scope and either path would require a standard (EIP or ethereum-magicians post) I'm closing this until a suitable proposal is drafted.