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With CosmWasm

CosmWasm is an advanced smart contracting platform built for the Cosmos ecosystem. Cosm refers to “Cosmos” while Wasm refers to WebAssembly. CosmWasm uniquely enables developers to build multi-chain smart contracts, making use of the InterBlockchain Communication (IBC) Protocol.

CosmWasm contract can update and fetch the prices from Band Standard Dataset using Band's CosmWasm contract, deployed on their network.

The deployed contract addresses can be found in Supported Blockchains Section.

Build​

Contract​

To compile all contracts, run the following script in the repo root: /scripts/build_artifacts.sh or the command below: The optimized wasm code and its checksums can be found in the /artifacts directory

docker run --rm -v "$(pwd)":/code \
  --mount type=volume,source="$(basename "$(pwd)")_cache",target=/code/target \
  --mount type=volume,source=registry_cache,target=/usr/local/cargo/registry \
  cosmwasm/workspace-optimizer:0.12.7

Schema​

To generate the JSON schema files for the contract call, queries and query responses, run the following script in the repo root: /scripts/build_schemas.sh or run cargo schema in the smart contract directory.

Usage​

To query the prices from Band Protocol's StdReference contracts, the contract looking to use the price values should query Band Protocol's std_reference contract.

QueryMsg​

The query messages used to retrieve price data for price data are as follows:

pub enum QueryMsg {
    GetReferenceData {
        // Symbol pair to query where:
        // symbol_pair := (base_symbol, quote_symbol)
        // e.g. BTC/USD ≡ ("BTC", "USD")
        symbol_pair: (String, String),
    },
    GetReferenceDataBulk {
        // Vector of Symbol pair to query
        // e.g. <BTC/USD ETH/USD, BAND/BTC> ≡ <("BTC", "USD"), ("ETH", "USD"), ("BAND", "BTC")>
        symbol_pairs: Vec<(String, String)>,
    },
}

ReferenceData​

ReferenceData is the struct that is returned when querying with GetReferenceData or GetReferenceDataBulk where the bulk variant returns Vec<ReferenceData>

ReferenceData is defined as:

pub struct ReferenceData {
    // Pair rate e.g. rate of BTC/USD
    pub rate: Uint256,
    // Unix time of when the base asset was last updated. e.g. Last update time of BTC in Unix time
    pub last_updated_base: Uint64,
    // Unix time of when the quote asset was last updated. e.g. Last update time of USD in Unix time
    pub last_updated_quote: Uint64,
}

Examples​

Single Query​

For example, if we wanted to query the price of BTC/USD, the demo function below shows how this can be done.

fn demo(
    std_ref_addr: Addr,
    symbol_pair: (String, String),
) -> StdResult<ReferenceData> {
    deps.querier.query_wasm_smart(
        &std_ref_addr,
        &QueryMsg::GetReferenceData {
            symbol_pair,
        },
    )
}

Where the result from demo(std_ref_addr, ("BTC", "USD")) would yield:

ReferenceData(23131270000000000000000, 1659588229, 1659589497)

and the results can be interpreted as:

  • BTC/USD
    • rate = 23131.27 BTC/USD
    • lastUpdatedBase = 1659588229
    • lastUpdatedQuote = 1659589497

Bulk Query​

fn demo(
    std_ref_addr: Addr,
    symbol_pairs: Vec<String>,
) -> StdResult<ReferenceData> {
    deps.querier.query_wasm_smart(
        &std_ref_addr,
        &QueryMsg::GetReferenceDataBulk {
            symbol_pairs,
        },
    )
}

Where the result from demo(std_ref_addr, [("BTC", "USD"), ("ETH", "BTC")]) would yield:

[
    ReferenceData(23131270000000000000000, 1659588229, 1659589497),
    ReferenceData(71601775432131482, 1659588229, 1659588229)
]

and the results can be interpreted as:

  • BTC/USD
    • rate = 23131.27 BTC/USD
    • lastUpdatedBase = 1659588229
    • lastUpdatedQuote = 1659589497
  • ETH/BTC
    • rate = 0.07160177543213148 ETH/BTC
    • lastUpdatedBase = 1659588229
    • lastUpdatedQuote = 1659588229