Because AAVE contains many contracts, its deployment process is correspondingly complex. AAVE splits deployment into seven tasks, each implemented as a hardhat task, and then uses a full task to orchestrate deployment and initialization end to end.
Inside package.json, the project defines many deployment commands. The following one deploys to mainnet and verifies contracts:
A flash loan is a loan that is borrowed and repaid within a single transaction, without collateral. The key is that everything happens inside one transaction. Because repayment happens in the same transaction, no collateral is required. The blockchain can verify whether the repayment amount is greater than or equal to the principal plus interest. If it is not, the whole transaction reverts and all state changes are rolled back. In other words, the borrowed funds are rolled back too, so the lender takes no risk.
Flash loans can also generate meaningful fee income. A single block only lasts a few seconds, yet the protocol can charge 9 basis points. In practice, flash loans are often used with very large position sizes, easily tens or even hundreds of millions of dollars.
Several parameters inside the AAVE interest-rate model interact with one another in fairly complex ways. Stable-rate borrowing is especially tricky, and the formula for the average stable rate is particularly hard to read. In real lending markets, however, many assets do not even support stable-rate borrowing, and among the assets that do, the share of stable-rate debt is very small, often well below 1%. So for beginners, it is completely reasonable to skip the stable-rate part on a first pass.
There are a few points worth highlighting in AAVE’s interest-rate logic:
AAVE accrues interest based on timestamps, while Compound accrues interest based on block numbers. In both protocols, rate updates are triggered by actions such as deposit, withdraw, borrow, and repay, and they are only meaningfully updated once per block.balanceOf method on aToken and debtToken returns the amount of underlying deposit or debt, not merely the raw token share amount.If all you need is the high-level picture, the core AAVE flows can be summarized like this. The relevant code lives mainly in the LendingPool contract.
Centralized exchanges rely on a CLOB, or central limit order book, for matching. The matching rules are simple: price priority first, time priority second. For an exchange, the matching engine is foundational infrastructure. It must be stable, efficient, scalable, and fault-tolerant, and it must be able to recover or roll back quickly during extreme market conditions or system failures.
The transaction fee of uniswap is derived from the identity of x * y = K. In a specific transaction scenario, such as a loopback transaction, our transaction cost can be far lower than the rated fee.
The loopback transaction is a transaction in a transaction pair tokenA/tokenB, first exchange tokenA to get tokenB, and then immediately exchange the obtained tokenB back to tokenA.
The standard rate of uniswap v2 is 0.3%, then the cost of loopback transaction is 0.6%, this cost is quite high. If we are just to brush the transaction volume, we need an effective way to reduce Handling fees, loopback transactions are a very effective way.
In simple terms, a meta transaction is a transaction submitted by a third party on behalf of the user.
The usual flow is:
The interest-rate model and risk control are the core of any lending protocol. In AAVE, interest updates can be divided into three parts:
As for risk control, I discuss that separately in a later article.
AAVE is a lending protocol, so its core revolves around four major actions: deposit, borrow, repay, and liquidation. In my view, one major reason AAVE looks complex is the existence of stable-rate borrowing, which significantly increases the complexity of the interest-rate model. Without that feature, the overall design would be much easier to understand.
The high-level AAVE architecture looks like this:
Lending was one of the earliest major applications in DeFi. A lending protocol is a smart-contract system that allows users to deposit and borrow tokens. In that sense it resembles a bank: depositors place assets into a lending application, the application lends those assets to borrowers, and depositors earn interest over time. When a borrower’s position becomes undercollateralized, liquidation is triggered. Anyone can participate in the liquidation process, and successful liquidators receive a reward. The liquidation system protects the solvency of the lending market and, in turn, the interests of depositors.