mirror of
https://github.com/pezkuwichain/pezkuwi-subxt.git
synced 2026-05-30 21:01:02 +00:00
Tomasz Drwięga
5169155f94
* Add instructions. * Squashed 'bridges/' content from commit 345e84a21 git-subtree-dir: bridges git-subtree-split: 345e84a2146b56628e9888c9f5e129cb40e868a9 * Remove bridges workspace file to avoid confusing Cargo. * Add some bridges primitives to Polkadot workspace. * Improve docs.
72 lines
3.8 KiB
Markdown
72 lines
3.8 KiB
Markdown
# PoA Ethereum High Level Documentation
|
|
|
|
NOTE: This is from the old README
|
|
|
|
### Ethereum Bridge Runtime Module
|
|
The main job of this runtime module is to keep track of useful information an Ethereum PoA chain
|
|
which has been submitted by a bridge relayer. This includes:
|
|
|
|
- Ethereum headers and their status (e.g are they the best header, are they finalized, etc.)
|
|
- Current validator set, and upcoming validator sets
|
|
|
|
This runtime module has more responsibilties than simply storing headers and validator sets. It is
|
|
able to perform checks on the incoming headers to verify their general integrity, as well as whether
|
|
or not they've been finalized by the authorities on the PoA chain.
|
|
|
|
This module is laid out as so:
|
|
|
|
```
|
|
├── ethereum
|
|
│ └── src
|
|
│ ├── error.rs // Runtime error handling
|
|
│ ├── finality.rs // Manage finality operations
|
|
│ ├── import.rs // Import new Ethereum headers
|
|
│ ├── lib.rs // Store headers and validator set info
|
|
│ ├── validators.rs // Track current and future PoA validator sets
|
|
│ └── verification.rs // Verify validity of incoming Ethereum headers
|
|
```
|
|
|
|
### Currency Exchange Runtime Module
|
|
The currency exchange module is used to faciliate cross-chain funds transfers. It works by accepting
|
|
a transaction which proves that funds were locked on one chain, and releases a corresponding amount
|
|
of funds on the recieving chain.
|
|
|
|
For example: Alice would like to send funds from chain A to chain B. What she would do is send a
|
|
transaction to chain A indicating that she would like to send funds to an address on chain B. This
|
|
transaction would contain the amount of funds she would like to send, as well as the address of the
|
|
recipient on chain B. These funds would now be locked on chain A. Once the block containing this
|
|
"locked-funds" transaction is finalized it can be relayed to chain B. Chain B will verify that this
|
|
transaction was included in a finalized block on chain A, and if successful deposit funds into the
|
|
recipient account on chain B.
|
|
|
|
Chain B would need a way to convert from a foreign currency to its local currency. How this is done
|
|
is left to the runtime developer for chain B.
|
|
|
|
This module is one example of how an on-chain light client can be used to prove a particular action
|
|
was taken on a foreign chain. In particular it enables transfers of the foreign chain's native
|
|
currency, but more sophisticated modules such as ERC20 token transfers or arbitrary message transfers
|
|
are being worked on as well.
|
|
|
|
## Ethereum Node
|
|
On the Ethereum side of things, we require two things. First, a Solidity smart contract to track the
|
|
Substrate headers which have been submitted to the bridge (by the relay), and a built-in contract to
|
|
be able to verify that headers have been finalized by the GRANDPA finality gadget. Together this
|
|
allows the Ethereum PoA chain to verify the integrity and finality of incoming Substrate headers.
|
|
|
|
The Solidity smart contract is not part of this repo, but can be found
|
|
[here](https://github.com/svyatonik/substrate-bridge-sol/blob/master/substrate-bridge.sol) if you're
|
|
curious. We have the contract ABI in the `ethereum/relays/res` directory.
|
|
|
|
## Rialto Runtime
|
|
The node runtime consists of several runtime modules, however not all of them are used at the same
|
|
time. When running an Ethereum PoA to Substrate bridge the modules required are the Ethereum module
|
|
and the currency exchange module. When running a Substrate to Substrate bridge the Substrate and
|
|
currency exchange modules are required.
|
|
|
|
Below is a brief description of each of the runtime modules.
|
|
|
|
## Bridge Relay
|
|
The bridge relay is responsible for syncing the chains which are being bridged, and passing messages
|
|
between them. The current implementation of the relay supportings syncing and interacting with
|
|
Ethereum PoA and Substrate chains.
|