Smart Order Router (SOR)

Smart Order Router, or SOR, is an off-chain linear optimization of routing orders across pools for best price execution.

SOR exists in the Bronze release as a way to aggregate liquidity across all Balancer pools. Future releases of Balancer will accomplish this on-chain and allow aggregate contract fillable liquidity.

Liquidity aggregators are free to use the SOR npm package or create their own order routing across pools.

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Overview Of Use And Example

There are two types of swap available:

swapExactIn - i.e. You want to swap exactly 1 ETH as input and SOR will calculate X amount of BAL you receive in return.
or
swapExactOut - i.e. You want to receive exactly 1 BAL and SOR will calculate X amount of ETH you must input.

The SOR will return totalReturn/totalInput as well as a list swaps to achieve the total. Swaps can be through direct pools, i.e. A > POOL1 > B, or via a multihop pool, i.e. A > POOL1 > C > POOL2 > B. The swaps can be executed directly on-chain or with something like the ExchangeProxy.

Example Output:

// Following is output for 1USDC->WETH swapExactIn
[
    swaps,
    amountOut,
] = await SOR.getSwaps(....

  console.log(
      `USDC>WETH, SwapExactIn, 1USDC, Total WETH Return: ${amountOut.toString()}`
  );
  // USDC>WETH, SwapExactIn, 1USDC, Total WETH Return: 3090385829490120 - This is the total amount of WETH received for 1USDC
  console.log(`Swaps: `);
  console.log(swaps);

  /*
    This demonstrates a multihop swap going:
    USDC -> BTC++ via pool 0x75286...
    Then BTC++ -> WETH via pool 0xd4dbf...
  */
  [
    // Multihop swap
    [
      // First sequence in swap
      {
        pool: '0x75286e183d923a5f52f52be205e358c5c9101b09',
        tokenIn: '0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48',
        tokenOut: '0x0327112423f3a68efdf1fcf402f6c5cb9f7c33fd',
        swapAmount: '1000000',
        limitReturnAmount: '0',
        maxPrice: '115792089237316195423570985008687907853269984665640564039457584007913129639935'
       },
      // Second sequence in swap
      {
        pool: '0xd4dbf96db2fdf8ed40296d8d104b371adf7dee12',
        tokenIn: '0x0327112423f3a68efdf1fcf402f6c5cb9f7c33fd',
        tokenOut: '0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2',
        swapAmount: '89403274570637',
        limitReturnAmount: '0',
        maxPrice:'115792089237316195423570985008687907853269984665640564039457584007913129639935'
      }
    ]
  ]

The file: example-swapExactIn.ts, shows full examples with comments for various swaps.

To Run:

Create a .env file in root dir with your infura provider key: INFURA=your_key

Install dependencies: $ yarn install

Run example: $ ts-node ./test/testScripts/example-swapExactIn.ts