Port validator_service.py to web3.py

[djrtwo]

Due to the pending deprecation of the pethereum/pyethapp stack, I propose porting existing validator_service.py functionality to use web3.py. Not only is web3.py well-featured and actively developed, web3.py can plug into any client that conforms to the standard json-rpc interface. This is particularly exciting because a web3.py validator_service will be able to plug into any of the major clients (yay code reuse).

Proposed Implementation

I haven't fully spec'd this out yet, but it should be a natural translation from pyethapp to web3.py. More details to follow.

• port functionality 1:1 from pyethapp to web3.py
• new service will live in this repo
• move contract tests to tests/contracts
• add new service tests at tests/service

[ChihChengLiang]

Note that other clients still need to implement features such as:

• Casper Fork Choice Rule
• Epoch initialization
• Casper Vote Gas Refunds
• Casper Block Ordering

specified in the spec

[djrtwo]

Absolutely. In the issue, I should note that this is for when other clients implement the casper spec.

[djrtwo]

decimal10 support in web3.py is currently a blocker
ethereum/web3.py#700

[pipermerriam]

Someone can start on decimal10 abi support now. The implementation should be done in eth-abi and should be reasonably straight forward to do if you dig in and look at how the current encoders/decoders are written.

[djrtwo]

eth-abi library is waiting on decision to be made on whether vyper is going to keep decimal10 or just move to support fixedNxM

vyperlang/vyper#566