arbitrum-mpp

Make payments using MPP (Machine Payments Protocol) on Arbitrum.

package structure

arbitrum-mpp/
├── src/
│   ├── index.ts              # Re-export shared schemas
│   ├── Methods.ts            # Shared Method.from() definitions
│   ├── default.ts            # Default shared values
│   ├── client/
│   │   ├── index.ts          # ./client entry point
│   │   └── Charge.ts         # Client charge implementation
│   └── server/
│       ├── index.ts          # ./server entry point
│       └── Charge.ts         # Server charge implementation
└── test/
│   ├── client.ts             # example client implementation
│   └── server.ts             # example server implementation
├── package.json
└── tsconfig.json

client/Charge.ts is responsible for taking a servers Challenge and creating a Credential which contains a signature and information about how the client wants to pay, what they want to pay for, etc

server/Charge.ts is responsible for both defining the Challenge along with taking in a clients Credential and checking its validity. If valid, the server will submit the transaction and verify the payment went through.

Useful documentation references:

• Protocol-overview
• Custom-First-party-SDK
• Method.from
• Method.toServer
• Method.toClient
• Unified-EVM-Spec

Running the test

To try it out locally, start the server in one terminal:

npm run server

Then, in a separate terminal, run the client:

npm run client

Make sure the server has eth and the client has a compatible ERC-20 (Currently only USDC)