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.
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.
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 are returned in a format that can be directly to the Vault to execute the trade.
The example file
swapExample.ts in: ./testScripts, demonstrates full examples with comments.
Create a .env file in root dir with your infura provider key:
$ yarn install
$ ts-node ./test/testScripts/swapExample.ts
Optional config values can be set in the .env file:
PRICE_ERROR_TOLERANCE - how close we expect prices after swap to be in SOR suggested paths. Defaults 0.00001.
INFINITESIMAL - Infinitesimal is an amount that's used to initialize swap amounts so they are not zero or the path's limit. Defaults 0.000001.