DIA WASM Oracle

This project contains the diadata Key/Value oracle written using wasm (web-assembly), which can be deployed to supported substrate chains. A demo instance is currently deployed on Shibuya testnet.

Functions of the Wasm Oracle

get : Gets the latest value of the asset symbol with timestamp. Can be called by anyone.

set : Sets latest value of asset, requires price and timestamp. Can be called only by the owner of contract.

Deployed Contracts

A demo instance of this contract is currently deployed to Astar Shibuya Testnet:

Network Name	Contract address
Astar testnet (Shibuya)	X5NLwAUYX7FwVk25a8JwaXtuVJQsW87GQcKxYoF3aLyu8Pz
Astar (Shiden)	Xen1nSvxorHMNx2a9YDDGMw6LXVr7Bn4u9as3917Lv5MZLn

Using a DIA Oracle in Your Contracts

To access values from DIA wasm oracles you need to copy the diadata directory to your contract so that you can access DIA structs, that contain the oracle data.

Changes in Your Contract

Create storage with DiaDataref, this is used to access values from oracle

    #[ink(storage)]
    pub struct OracleExample {
        diadata: DiadataRef,
        ....
        ....
    }

This struct can be used to access data from pub functions from the oracle contract.

Link DiadataRef with Deployed DIA Oracle

To instantiate a contract's access to the oracle you need to pass the DIA oracle address, either using the constructor or by creating a separate write function to update with the value of oracle at a later stage.

Example using constructor

        #[ink(constructor)]
        pub fn new(
            oracle_address: AccountId, 
        ) -> Self {
            let diadata: DiadataRef = ink_env::call::FromAccountId::from_account_id(oracle_address);  
            Self {
                diadata
            }
        }

Here,oracle_address refers to the DIA oracle address of a deployed oracle contract.

Access Value

Next, to access an oracle value you can simple call the get() function

 pub fn get(&self ) -> diadata::ValueTime {
            return self.diadata.get(String::from("ETH"));
        }

This gives the ETH price value time given by the oracle.

Config Changes

Make sure you add diadata/std in you config

std = [
    "ink_metadata/std",
    "ink_env/std",
    "ink_storage/std",
    "ink_primitives/std",
    "scale/std",
    "scale-info/std",
    "diadata/std",

]

Make sure the version of ink you are on is v3.0.1

Running the Oracle Service Yourself

You can also run a copy of the oracle service yourself on any supported wasm chain. This is not necessary to access data on an existing oracle.

Deploy the Oracle Contract

You can deploy the oracle contract using the polkadot.js web interface: https://polkadot.js.org/apps/?rpc=wss%3A%2F%2Frpc.shibuya.astar.network#/contracts

Setup Instructions for Cargo Contract

To develop smart contracts in wasm with ink, run the setup of cargo-contract first:

https://github.com/paritytech/cargo-contract

Set the required environment variables for the oracle feeder:

PRIVATE_KEY=<private key of the updater address in json format>
UNLOCK_PASSWORD=<optional password for the private key>
CONTRACT_ADDRESS=<address of deployed wasm contract>
RPC_ADDRESS=<HTTP address of the node to connect to>
SYMBOLS=<comma separated values of asset symbols to update>

After setting up these environmnet variables you can run the following commands to start the feeder service:

cd oracle
npm run build
npm run start