# Protocol Integration

The WDK Core module supports registering external protocols. This allows you to extend the basic wallet functionality with advanced features like [token swapping](#swapping-tokens), [cross-chain bridging](#bridging-assets), and lending, all through a unified interface.

## Register Protocols

You can register protocols globally (for all new accounts).

### Global Registration (Recommended)

Global registration ensures that every account you retrieve already has the protocol ready to use. You can do this by chaining a call to `.registerProtocol()` on the WDK instance.

### 1. Install Protocol Modules

Install the [`@tetherto/wdk-protocol-swap-velora-evm`](https://www.npmjs.com/package/@tetherto/wdk-protocol-swap-velora-evm) and [`@tetherto/wdk-protocol-bridge-usdt0-evm`](https://www.npmjs.com/package/@tetherto/wdk-protocol-bridge-usdt0-evm) packages:

```bash
npm install @tetherto/wdk-protocol-swap-velora-evm && npm install @tetherto/wdk-protocol-bridge-usdt0-evm
```

### 2. Register in Code

Now, import the protocol modules and register them with your WDK instance. This makes the protocol methods available to any account derived from that instance.

First, import the necessary modules:

{% code title="Import Protocols" lineNumbers="true" %}

```typescript
import veloraProtocolEvm from '@tetherto/wdk-protocol-swap-velora-evm'
import usdt0ProtocolEvm from '@tetherto/wdk-protocol-bridge-usdt0-evm'
```

{% endcode %}

Then, register the protocols for the specific chains they support:

{% code title="Register Protocols" lineNumbers="true" %}

```typescript
// Register protocols for specific chains
const wdk = new WDK(seedPhrase)
  .registerWallet('ethereum', WalletManagerEvm, ethConfig)
  
  // Register Velora Swap for Ethereum
  .registerProtocol('ethereum', 'velora', veloraProtocolEvm, {
    apiKey: 'YOUR_API_KEY'
  })
  
  // Register USDT0 Bridge for Ethereum
  .registerProtocol('ethereum', 'usdt0', usdt0ProtocolEvm, {
     ethereumRpcUrl: 'https://eth.drpc.org' // Configuration depends on the module
  })
```

{% endcode %}

## Use Protocols

Once [registered](#register-protocols), you can access the protocol instance using the specific getter methods: `getSwapProtocol`, `getBridgeProtocol`, or `getLendingProtocol`.

### Swapping Tokens

Use `getSwapProtocol` to access registered swap services on any wallet account.

{% code title="Swap Tokens" lineNumbers="true" %}

```typescript
const ethAccount = await wdk.getAccount('ethereum', 0)
const velora = ethAccount.getSwapProtocol('velora')

const result = await velora.swap({
  tokenIn: '0x...', // Address of token to sell
  tokenOut: '0x...', // Address of token to buy
  tokenInAmount: 1000000n // Amount to swap
})
```

{% endcode %}

### Bridging Assets

1. Use `getBridgeProtocol` to access cross-chain bridges.
2. Call `bridge` from the bridge protocol to send tokens from one protocol to another.

{% code title="Bridge Assets" lineNumbers="true" %}

```typescript
const ethAccount = await wdk.getAccount('ethereum', 0)
const usdt0 = ethAccount.getBridgeProtocol('usdt0')

const result = await usdt0.bridge({
  targetChain: 'ton',
  recipient: 'UQBla...', // TON address
  token: '0x...', // ERC20 Token Address
  amount: 1000000n
})
```

{% endcode %}

{% hint style="info" %}
**Protocol Availability:** If you try to access a protocol that hasn't been registered (e.g., `getSwapProtocol('uniswap')`), the SDK will throw an error. always ensure registration matches the ID you request.
{% endhint %}

## Next Steps

Learn how to [configure middleware](https://docs.wdk.tether.io/sdk/core-module/usage/middleware) to add logging or failover protection to your wallet interactions.