To better understand the transaction flow for a Chain Abstracted dApp, let’s look at an example scenario where an Aave user would like to enter into a position on Polygon using their USDC balance on Optimism.

From the user’s perspective, they would simply connect their wallet and begin lending. Under the hood, the Aave app would initiate a crosschain transaction from the user’s wallet on Optimism directly into the Aave position on Polygon.

🖊️ Importantly, the user pays gas and funds for the above transaction entirely on Optimism

Here's a breakdown of the transaction flow:

For the above example case with Aave:

1. The user initiates the transaction to deposit into a pool on Aave-Polygon using their funds on Optimism.
2. The application calls xcall passing in the user’s USDC along with calldata related to the transaction on Polygon, and a target (which in this case is an adapter contract implementing an xReceive function).
3. Within the next 45-180 seconds (depending on the finality time of the source chain), Connext makes a transaction to the target, passing the user’s USDC and calldata into xReceive.
4. The xReceive function unpacks the calldata and uses it to call Aave’s supply function.

💡 In Connext, the gas fees for the Aave call on Polygon are paid by the user upfront on Optimism (in oETH). If the user’s transaction is underpriced (i.e. the gas price on Polygon increases during the transaction), the user can simply bump their gas similar to resubmitting underpriced transactions on Ethereum!