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NEAR contract template

NEAR protocol SDK makes it easy for NEAR developers in the NEAR Ecosystem to use Dante Network to interact with other chains, such as POLKADOT, Ethereum, Avalanche, Flow, etc.

Install dependency

# For compile contract
curl --proto '=https' --tlsv1.2 https://sh.rustup.rs -sSf | sh
source $HOME/.cargo/env
rustup target add wasm32-unknown-unknown
# For interact with the NEAR blockchain.
npm install -g near-cli

Click use this templete to start your multi-ecosystem dApp.

  • Create your project in project. You can find more details there.
  • Refer to the greeting or computing case to build your project.

Or you can use this SDK as a library by adding

protocol_sdk = { path = "<local path of protocol_sdk>/protocol_sdk"}

Library

call_cross

The function call_cross sends a cross-chain message, and without return.

Example is shown below, or you can refer it in the example greeting.

pub fn send_greeting(&self, to_chain: String, title: String, content: String, date: String) {
    let mut payload = Payload::new();
    let greeting_data = Value::VecString(vec!["NEARTEST".to_string(), title, content, date]);
    payload.push_item("greeting".to_string(), greeting_data);
    ....
    let content = Content {
        contract: contract.contract_address.clone(),
        action: contract.action_name.clone(),
        data: payload,
    };
    self.omni_chain.call_cross(to_chain, content);
}

call_cross_with_session

The function call_cross_with_session sends a cross-chain message, and returns the session id, which is equal the sent message id recorded in the cross-chain contract. Later a callback in the application contract will be called.

Example is shown below, or you can refer it in the example computing.

pub fn send_compute_task(&mut self, to_chain: String, nums: Vec<u32>) -> PromiseOrValue<u64> {
    let mut payload = Payload::new();
    payload.push_item("nums".to_string(), Value::VecUint32(nums.clone()));
    ...
    let callback = "receive_compute_result".to_string();
    self.omni_chain
        .call_cross_with_session(to_chain.clone(), content, callback)
        .then(ext_self::callback(
            to_chain,
            nums,
            env::current_account_id(),
            NO_DEPOSIT,
            GAS_FOR_CALLBACK,
        ))
        .into()
}

send_response_message

The function cross_chain_respond responds a cross-chain request, and returns the session id recorded in the cross-chain contract.

Example is shown below, or you can refer it in the example computing.

pub fn receive_compute_task(&self, payload: Payload, context: Context) {
    ...
    let content = Content {
        contract: context.sender,
        action: context.session.callback.unwrap(),
        data: payload,
    };
    self.omni_chain
        .send_response_message(context.from_chain, content, context.session.id);
}

Examples

Compile smart contract

cd examples/greeting
RUSTFLAGS='-C link-arg=-s' cargo build --target wasm32-unknown-unknown --release
mkdir -p ./res && cp target/wasm32-unknown-unknown/release/greeting.wasm ./res/

Deploy smart contract to NEAR testnet

cd examples/greeting
near deploy $CONTRACT_ID --wasmFile res/greeting.wasm --accountId $CONTRACT_ID