We have built a Decentralized limit orders platform boosted by market making where we use the idle money that's sits in the smart contracts when ever user places the limit orders. No body actually want to make their money sit idle in the smart contracts.
For this hack we just used WETH/DAI token pair and all our contracts are being deployed on the kovan test network.
Advantages: This is very capital efficient. So we're relaying the deposit amount into different protocols as long as user won't withdraw money from the smart contract.
Provides liquidity to the protocols this is actually market making.
Limitations: Dependency on other protocols.
Centralized execution service.
No lending rates oracles.
High cost of order creation due to new contract deployment.
For this hack we have used Aave, Kyber and Chainlink protocols.
Aave: To get the APR on the amount that users deposit.
Kyber: To get the liquidity and purchase the destination amount.
Chainlink: To get the prices of the individual tokens.
So whenever user places the order we relay that into Aave and user will start accuring interest. And you can also execute the order anytime but chainlink price oracle always check the current price and executes the order accordingly.