Single-chain Apps

Building a decentralized application (dapp) on a rollup integrated with Espresso unlocks faster, more reliable confirmations without changing how you interact with the chain at the RPC level.

Normally, rollup applications rely on the parent chain (e.g., Ethereum) to provide finality. For optimistic rollups, this can take up a few hours.

For most dapps, waiting for this kind of finality is too slow. Users need faster confirmations for actions like:

• Sending tokens

• Swapping in a DEX

• Playing a game

• Interacting with NFTs

Espresso provides fast, trust-minimized confirmations that dapps can rely on immediately. By reading from a Caff Node, your app can present users with consistent and near-instant transaction results.

Typical Data Flow

Let’s walk through a transaction step by step:

1. User submits a transaction

The user signs and submits a transaction through your dapp’s frontend.

2. Sequencing

The transaction is forwarded to the rollup’s sequencer (which could be centralized or decentralized). Anyway, the Espresso Network provides confirmation of the transaction ordering.

3. Caff Node derives the state

The Caff Node listens to Espresso confirmations and derives the correct rollup state in real time.

It exposes this state via the standard Ethereum-style JSON-RPC interface.

4. Frontend shows confirmation

Your dapp queries the Caff Node just like it would a normal RPC.

Because Espresso confirmations are fast, the user sees their transaction confirmed almost instantly.

5. Parent chain

Later, the batch is posted to the parent chain (Ethereum, Arbitrum, etc.) but your app doesn’t need to wait for it to provide a smooth UX.

Example: Token Swap on Rari

Suppose you’re building a DEX on Rari (an L3 integrated with Espresso).

- Without Espresso: A user swaps tokens, but your frontend can only show “pending” until the rollup batch is posted and eventually finalized on Arbitrum. This could take minutes to hours.

- With Espresso: The user submits the swap, Espresso confirms it within seconds, and your frontend shows the updated balances immediately by querying a Caff Node.

Later, Arbitrum finality and settlement guarantees long-term security, but the user never notices the delay.