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bridge's Introduction

Polkadot bridge SDK

Polkadot bridge SDK for multi-chain cross-chain token transfer.

You can integrate the amazing multi-chain bridge into your DApp with this SDK.

And you're welcome to add your parachain-adapter into the SDK.

Supported channels

All channels support transfers in both directions.

Interlay:

channel tokens
acala INTR IBTC
astar INTR IBTC
parallel INTR IBTC
polkadot DOT
polkadot asset hub USDT
hydradx IBTC

Kintsugi:

channel tokens
bifrost VKSM
heiko KBTC KINT
karura KBTC KINT LKSM
kusama KSM
kusama asset hub USDT

Polkadot:

channel tokens
polkadot asset hub DOT

Kusama:

channel tokens
kusama asset hub KSM

Usage

Example: src/bridge.spec.ts

1. initiate the bridge SDK

/// import any parachain-adapters you want in your bridge.
const availableAdapters: Record<string, BaseCrossChainAdapter> = {
  polkadot: new PolkadotAdapter(),
  // kusama: new KusamaAdapter(),
  acala: new AcalaAdapter(),
  // karura: new KaruraAdapter(),
  // statemine: new StatemineAdapter(),
  // bifrost: new BifrostAdapter(),
  // ...
};

/// create your bridge instance and pass the adapters to it.
const bridge = new Bridge({
  adapters: Object.values(availableAdapters),
});

Then you can get the bridge routers:

const allRouters = bridge.router.getRouters();
/// or the available routers (some may temporarily unavailable)
const availableRouters = bridge.router.getAvailableRouters();

/// and get filtered routers
const destChains = bridge.router.getDestinationChains({ from: "interlay" });
const tokens = bridge.router.getAvailableTokens({
  from: "interlay",
  to: "polkadot",
});

2. network connection

You can use the ApiProvider of the SDK which can connect to all the parachains https://polkadot.js.org/apps supported, or you can use your own apiProvider.

import { ApiProvider } from "./api-provider";

const provider = new ApiProvider();

Connect network and pass the ApiPromise | ApiRx into the adapters.

// list all available from-chains
const chains = Object.keys(availableAdapters) as ChainName[];

// connect all adapters
const connected = await firstValueFrom(
  provider.connectFromChain(chains, undefined)
);

// and set `ApiPromise | ApiRx` for each adapter
await Promise.all(
  chains.map((chain) => availableAdapters[chain].setApi(provider.getApi(chain)))
);

3. token balance query & token transfer

/// balance query
const balance = await firstValueFrom(
  adapter.subscribeTokenBalance(token, testAccount)
);

/// and you may want to use the inputConfig provided by the SDK
/// to limit user's transfer amount input
const inputConfig = await firstValueFrom(
  adapter.subscribeInputConfigs({
    to: toChain,
    token,
    address: toAddress,
    signer,
  })
);
console.log(
  inputConfig.minInput,
  inputConfig.maxInput,
  inputConfig.destFee,
  inputConfig.estimateFee,
  inputConfig.ss58Prefix
);

/// create tx & send
const tx = adapter.createTx({
  amount: FixedPointNumber.fromInner("10000000000", 10),
  to: "polkadot",
  token: "DOT",
  address: toAddress,
  signer: testAccount,
});
tx.signAndSend(keyPair, { tip: "0" }, onStatusChangecCallback);

How to integrate your parachain into the bridge sdk

For Substrate parachains

1. Add parachain config

Add a new item in src/configs/chains/polkadot-chains.ts or src/configs/chains/kusama-chains.ts.

/// karura for example
{
  karura: {
    id: 'karura',
    display: 'Karura',
    icon: 'https://resources.acala.network/networks/karura.png',
    paraChainId: 2000,
    ss58Prefix: 8
  }
  /// ...other parachains
}

2. Create adapter for your parachain

Add a new adapter file in src/adapters/, and create your ParachainAdapter class extends BaseCrossChainAdapter.

Example: src/adapters/bifrost.ts

2.1 define tokens and routers
/// bifrost for example
export const bifrostTokensConfig: Record<string, MultiChainToken> = {
  BNC: { name: "BNC", symbol: "BNC", decimals: 12, ed: "10000000000" },
  VSKSM: { name: "VSKSM", symbol: "VSKSM", decimals: 12, ed: "100000000" },
  /// ...other tokens
};
export const bifrostRoutersConfig: Omit<CrossChainRouterConfigs, "from">[] = [
  /// router for token `BNC` from `bifrost` to `karura`,
  /// `xcm.fee` defines the XCM-Fee on karura,
  /// `xcm.weightLimit` defines the weightLimit value used creating Extrinsic.
  {
    to: "karura",
    token: "BNC",
    xcm: {
      fee: { token: "BNC", amount: "932400000" },
      weightLimit: "Unlimited",
    },
  },
  /// router for token `KUSD` from `bifrost` to `karura`
  {
    to: "karura",
    token: "KUSD",
    xcm: {
      fee: { token: "KUSD", amount: "3826597686" },
      weightLimit: "Unlimited",
    },
  },
];
2.2 implement public method subscribeTokenBalance()

Implement the subscribeTokenBalance method so the bridge can query token balances.

/// 1. create `BifrostBalanceAdapter` extends `BalanceAdapter`.
class BifrostBalanceAdapter extends BalanceAdapter {
  private storages: ReturnType<typeof createBalanceStorages>;

  constructor ({ api, chain, tokens }: BalanceAdapterConfigs) {
    super({ api, chain, tokens });
    this.storages = createBalanceStorages(api);
  }

  public subscribeBalance (token: string, address: string): Observable<BalanceData> {
    /// ...balance queries
  }
}
/// 2. we use a `createBalanceStorages` function with acala `Storage` utils
///    for token balance queries here.
function createBalanceStorages(api: AnyApi) => {
  return {
    /// balances for native-token (BNC for bifrost)
    balances: (address: string) =>
      Storage.create<any>({
        api,
        path: 'query.system.account',
        params: [address]
      }),
    /// assets for non-native-token (KUSD for bifrost)
    assets: (tokenId: string, address: string) =>
      Storage.create<any>({
        api,
        path: 'query.tokens.accounts',
        params: [tokenId, address]
      })
  };
};
/// 3. implement the `subscribeTokenBalance` method
class BaseBifrostAdapter extends BaseCrossChainAdapter {
  private balanceAdapter?: BifrostBalanceAdapter;

  public subscribeTokenBalance (token: string, address: string): Observable<BalanceData> {
    return this.balanceAdapter.subscribeBalance(token, address);
  }
}
2.3 implement public method subscribeMaxInput()

Implement the subscribeMaxInput method so the bridge can set transferable token amount limit.

/// maxInput = availableBalance - estimatedFee - existentialDeposit
class BaseBifrostAdapter extends BaseCrossChainAdapter {
  public subscribeMaxInput(
    token: string,
    address: string,
    to: ChainName
  ): Observable<FN> {
    return combineLatest({
      txFee:
        token === this.balanceAdapter?.nativeToken ? this.estimateTxFee() : "0",
      balance: this.balanceAdapter
        .subscribeBalance(token, address)
        .pipe(map((i) => i.available)),
    }).pipe(
      map(({ balance, txFee }) => {
        const tokenMeta = this.balanceAdapter?.getToken(token);
        const feeFactor = 1.2;
        const fee = FN.fromInner(txFee, tokenMeta?.decimals).mul(
          new FN(feeFactor)
        );

        return balance
          .minus(fee)
          .minus(FN.fromInner(tokenMeta?.ed || "0", tokenMeta?.decimals));
      })
    );
  }
}
2.4 implement public method createTx()

Implement the createTx method so the bridge can create the cross-chain transfer Extrinsic.

/// maxInput = availableBalance - estimatedFee - existentialDeposit
class BaseBifrostAdapter extends BaseCrossChainAdapter {
  public createTx(
    params: CrossChainTransferParams
  ):
    | SubmittableExtrinsic<"promise", ISubmittableResult>
    | SubmittableExtrinsic<"rxjs", ISubmittableResult> {
    const { address, amount, to, token } = params;
    const toChain = chains[to];

    const accountId = this.api?.createType("AccountId32", address).toHex();

    const tokenId = SUPPORTED_TOKENS[token];
    if (!tokenId) {
      throw new CurrencyNotFound(token);
    }

    return this.api.tx.xTokens.transfer(
      tokenId,
      amount.toChainData(),
      {
        V1: {
          parents: 1,
          interior: {
            X2: [
              { Parachain: toChain.paraChainId },
              { AccountId32: { id: accountId, network: "Any" } },
            ],
          },
        },
      },
      this.getDestWeight(token, to)?.toString()
    );
  }
}
2.5 pass your routers config to your adapter
/// `chains.bifrost` is the config you added in step 1.
/// `bifrostRoutersConfig` & `bifrostTokensConfig` is the config you defined in step 2.1.
export class BifrostAdapter extends BaseBifrostAdapter {
  constructor() {
    super(chains.bifrost, bifrostRoutersConfig, bifrostTokensConfig);
  }
}

And you are all set now!

Additional steps

You can import your ParachainAdapter into src/bridge.spec.ts to test your adapter.

run testing with yarn test.

And remember to run yarn lint before commit your code.

For EVM parachains

TODO

bridge's People

Contributors

bvotteler avatar tomjeatt avatar romeroyang avatar sander2 avatar github-actions[bot] avatar ns212 avatar qwer951123 avatar actions-user avatar dependabot[bot] avatar nud3l avatar crypto-engineer avatar gxhx avatar

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