ABI Build Process

This document explains how ABI generation works during the Rust build process for Calimero applications.

Overview

The ABI generation process follows a two-step flow:

1. Generate ABI at build time as JSON - The build process analyzes your Rust code and generates a JSON Schema-based ABI
2. Optionally embed into WASM - The ABI can be embedded into the WASM binary for tools that may load/swap different WASMs

Build Script

Create a simple build.rs file:

use calimero_abi_emitter::emit_manifest;

fn main() {
    emit_manifest().expect("Failed to generate ABI manifest");
}

Type Mapping

Rust types are automatically mapped to ABI-compatible representations:

Rust Type	ABI Type	Notes
u8, u16, u32, u64	u8, u16, u32, u64	Direct mapping
i8, i16, i32, i64	i8, i16, i32, i64	Direct mapping
bool	bool	Direct mapping
String	string	UTF-8 string
Vec<T>	list<T>	Dynamic array
[T; N]	array<T, N>	Fixed-size array
Option<T>	T?	Nullable type
Result<T, E>	T	Success type only
BTreeMap<K, V>	map<K, V>	Key-value mapping
HashMap<K, V>	map<K, V>	Key-value mapping
struct S { ... }	record S { ... }	Record type
enum E { ... }	variant E { ... }	Variant type

ABI Extraction

Use the calimero-abi tool to extract the ABI from your WASM binary:

calimero-abi extract target/wasm32-unknown-unknown/release/my_app.wasm

Next Steps

• Configuration - Configure ABI generation for your project
• Rust Integration - Integrate ABI generation with your Rust code
• Validation - Set up ABI validation and testing