models.ts

Overview

The [models.ts](/projects/291/68901) file defines TypeScript interfaces that extend existing gas estimation and fee models to accommodate the specifics of the Optimism Layer 2 (L2) scaling solution for Ethereum. Specifically, it introduces additional gas-related fields relevant to transactions that involve both Layer 1 (L1) and Layer 2 layers in the Optimism network.

This file serves as a type definition module to ensure that gas estimation and fee data structures used throughout the application accurately reflect the dual-layer nature of Optimism transactions. It enables type-safe handling of these enhanced gas models in the application’s logic, UI, and API interactions.

Detailed Explanations

Interfaces

1. OptimismGasEstimate

export interface OptimismGasEstimate extends GasEstimate {
  l1GasLimit: string
}

• Description:
  Represents an estimated gas cost of a transaction that includes gas usage on both the Ethereum mainnet Layer 1 and the Optimism Layer 2.

• Extends:
  GasEstimate — imported from a common EVM API module, which typically contains standard gas estimation fields such as gasLimit and gasPrice.

• Properties:

  • l1GasLimit: string
    The gas limit specifically for the Layer 1 portion of the transaction, expressed as a string to handle large numeric values safely.

• Usage Example:

const estimate: OptimismGasEstimate = {
  gasLimit: "21000",
  gasPrice: "1000000000",
  l1GasLimit: "5000"
};

This interface would typically be used when estimating the total gas required for a transaction that will be executed on Optimism, including the L1 gas needed for finalization or rollup proofs.

2. OptimismGasFees

export interface OptimismGasFees extends GasFees {
  l1GasPrice: string
}

• Description:
  Represents the recommended fees for a transaction on both L1 and L2 in the Optimism network, extending the standard gas fee structure.

• Extends:
  GasFees — imported from the common EVM API module, which generally includes fee-related fields such as maxFeePerGas and maxPriorityFeePerGas.

• Properties:

  • l1GasPrice: string
    The current gas price for Layer 1, expressed as a string. This is important since fees on L1 affect the total cost of submitting transactions that eventually settle on the Ethereum mainnet.

• Usage Example:

const fees: OptimismGasFees = {
  maxFeePerGas: "2000000000",
  maxPriorityFeePerGas: "1000000000",
  l1GasPrice: "1500000000"
};

This interface is helpful for calculating the total fee to be paid for a transaction that involves both layers, ensuring the user or system accounts for L1 cost in addition to L2 fees.

Important Implementation Details

• Extending Existing Models:
  By extending GasEstimate and GasFees, the file leverages existing standardized models for Ethereum gas while adding Optimism-specific properties. This approach promotes code reuse and consistency.

• String Types for Gas Values:
  Gas limits and prices are expressed as strings rather than numbers to safely handle very large values that exceed JavaScript's safe integer range, avoiding precision loss.

• No Methods or Logic:
  This file only contains type definitions (interfaces) without any functions or classes. It is purely declarative and meant for type safety in TypeScript.

Interaction with Other Parts of the System

• Imports from Common API Module:
  The GasEstimate and GasFees interfaces are imported from a shared API module located at '../../../common/api/src/evm'. This implies these base models are shared across different parts of the application, possibly including backend services, frontend clients, or middleware.

• Usage in Transaction Gas Estimation and Fee Calculation:
  Modules responsible for estimating transaction costs on Optimism will use these interfaces to type their data structures. This can include services that:

  • Fetch gas estimates from RPC nodes or APIs,

  • Calculate total transaction fees,

  • Display gas costs in the UI,

  • Validate transaction parameters before submission.

• Layered Architecture Compliance:
  This file fits into the data modeling layer of the application’s architecture, defining domain-specific types that enable seamless integration between Ethereum Layer 1 and Optimism Layer 2 transaction handling.

Mermaid Class Diagram

classDiagram
    class GasEstimate {
        <<imported>>
        +gasLimit: string
        +gasPrice: string
        ...
    }

    class GasFees {
        <<imported>>
        +maxFeePerGas: string
        +maxPriorityFeePerGas: string
        ...
    }

    class OptimismGasEstimate {
        +l1GasLimit: string
    }
    OptimismGasEstimate --|> GasEstimate

    class OptimismGasFees {
        +l1GasPrice: string
    }
    OptimismGasFees --|> GasFees

Summary

• models.ts defines two interfaces, OptimismGasEstimate and OptimismGasFees, extending Ethereum gas estimation and fee models to include Layer 1 gas parameters specific to the Optimism network.

• These interfaces support accurate, type-safe representation of gas data for transactions involving both L1 and L2, crucial for correct fee calculation and transaction submission workflows.

• The file imports base models from a common API and adds properties as strings to handle large numerical values.

• It plays a foundational role in the application’s transaction gas estimation and fee calculation modules, ensuring seamless interaction between Ethereum mainnet and Optimism Layer 2 logic.