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Execution Model

Overview​

This page explains how cross-rollup transactions execute in Ethera, using a Rollup to Rollup bridge as the example. It covers who signs the transaction, which account executes it, and how messages and execution move across rollups.

The focus here is the route that uses Ethera's execution model most directly: cross-rollup execution coordinated through mailbox messaging, the Shared Publisher, and Two-Phase Commit. Sepolia deposit and withdrawal routes are documented separately in the bridge pages and tutorials.

Core Components​

Ethera's execution model is built from the following accounts, contracts, and coordination systems.

Accounts​

  • Connected Wallet: The externally owned account that the user controls
  • Smart Account: A contract-based execution account created through the Ethera SDK

Execution​

  • Account Abstraction: The account model that allows smart accounts to validate and execute flows
  • EntryPoint: The ERC-4337 execution contract used by smart-account flows

Bridge Contracts​

  • Rollup-to-Rollup Bridge: Used for transfers between Ethera rollups

Cross-Rollup Coordination​

  • Message-Passing Layer: Mailbox Contracts, which let one rollup write a message that another rollup can later consume
  • Coordination Layer: Shared Publisher, which drives atomic cross-rollup execution
  • Atomicity Model: Two-Phase Commit, which ensures the cross-rollup action completes together or does not complete at all

Smart-Account Execution​

Rollup to Rollup bridging requires coordinated execution across multiple rollups. In this route, the connected wallet signs the flow, while smart accounts execute the coordinated actions through UserOperations.

The smart accounts construct one or more UserOperations, which are validated and executed onchain by ERC-4337 EntryPoint.

At a high level, the smart-account flow works like this:

  1. The SDK creates or resolves the smart accounts on the required rollups
  2. The SDK builds one or more UserOperations for those smart accounts
  3. The connected wallet signs the flow
  4. EntryPoint executes the smart-account requests onchain
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An optional paymaster can sponsor smart-account execution costs, but it is not part of Ethera's core execution model.

Rollup to Rollup​

Rollup to Rollup bridging is the route that uses Ethera's cross-rollup execution model most directly.

Flow​

  1. The SDK resolves smart accounts on both rollups with the same multiChainIds configuration
  2. The connected wallet signs the flow
  3. EntryPoint executes the source smart-account call into ComposeL2ToL2Bridge
  4. The source bridge handles the asset according to its type:
    • ETH is locked into the liquidity path
    • Native ERC20 is locked on the source rollup
    • CET is burned on the source rollup
  5. The source bridge writes the outbound mailbox message
  6. The Shared Publisher coordinates the cross-rollup action
  7. Two-Phase Commit preserves atomic execution across rollups
  8. The corresponding inbound mailbox message becomes available on the destination rollup
  9. EntryPoint executes the destination smart-account call into receiveETH(...) or receiveTokens(...)
  10. The destination bridge releases the native asset or deploys and mints the required CET representation

Execution Model​

  • Signer: Connected Wallet
  • Source Execution Account: Smart Account on the source rollup
  • Source Bridge: ComposeL2ToL2Bridge
  • Message-Passing Layer: Mailbox Contracts
  • Coordination Layer: Shared Publisher
  • Atomicity Model: Two-Phase Commit
  • Destination Execution Account: Smart Account on the destination rollup
  • Destination Bridge: ComposeL2ToL2Bridge

Bridge-Specific Asset Handling​

Everything above describes Ethera's cross-rollup execution pattern. The bridge example adds asset-handling logic on top of that pattern.

ETH​

  • ETH stays native on the rollups
  • Rollup-to-rollup ETH uses the liquidity path rather than a CET representation

ERC20​

  • Native ERC20 assets are locked on the source rollup before the destination-side release
  • Rollups can hold CET representations of those assets
  • If a required destination representation does not already exist, the bridge can create it before minting
  • CET-based rollup-to-rollup transfers burn the source representation before the destination-side mint or release