Cross-Contract Example

This repo demonstrates cross-contract calls in Soroban smart contracts with different execution patterns and authorization requirements. It showcases how contracts can invoke other contracts in tree-like structures.

Requirements

• Deno - Modern runtime for JavaScript and TypeScript
• Stellar CLI - The command line interface to Stellar smart contracts

Setup

1. Copy the environment configuration:

cp .env.example .env

The .env is configured by default to use testnet. Feel free to adjust its parameters to use a different target network.

2. Build the contract:

stellar contract build

Examples

This project includes three different cross-contract execution patterns:

1. Simple Chain (simple)

A basic linear chain of contract calls:

A -> B -> C

• A calls B
• B calls C
• C is a leaf node
• No authorization required

Deploy and run:

deno task deploy:simple
deno task call:simple

2. Complex Tree (no-auth)

A complex tree structure with multiple branches:

                    A
                 /  |  \
                B   C   D
               /|   |   |\
              E F   G   H I
                        |
                        J

• A calls B, C, D
• B calls E, F
• C calls G
• D calls H, I
• H calls J
• E, F, G, I, J are leaf nodes
• No authorization required

Deploy and run:

deno task deploy:no-auth
deno task call:no-auth

3. Auth Tree (auth)

A balanced tree with distributed authorization requirements:

                         A (u1)
                    /         \
               B (u2)           C
              /       \         /  \
         D (u3)        E       F    G (u1, u3)
         /     \      /       /      \
        H       I    J (u2)  K        L (u2)

• A calls B, C (requires user1 authorization)
• B calls D, E (requires user2 authorization)
• C calls F, G (no auth required)
• D calls H, I (requires user3 authorization)
• E calls J (no auth required)
• F calls K (no auth required)
• G calls L (requires user1 + user3 authorization)
• H, I, J, K, L are leaf nodes

Authorization Summary:

• A: requires u1
• B: requires u2
• D: requires u3
• G: requires u1 + u3 (multi-signature)
• J: requires u2
• L: requires u2

Deploy and run:

deno task deploy:auth
deno task call:auth

How It Works

Each contract instance is configured during deployment with:

• Next contracts: Which contracts to call when execute() is invoked
• Auth addresses: Which user addresses must provide authorization

When you call execute() on the root contract:

1. It checks for required authorizations
2. Calls all configured next contracts
3. Each next contract repeats the process
4. Returns a list of all contract addresses that were invoked in the execution chain

The contract source lives at contracts/cross/src/contract.rs and implements a flexible pattern for cross-contract invocation testing.

Output

Each example will show:

• The tree structure being executed
• All contract addresses in the execution order
• Authorization requirements (for auth example)
• User keypairs (for auth example)

This allows you to test different cross-contract call patterns and understand how authorization flows through contract invocation chains in Soroban.