PayTube

A reference implementation of an off-chain state channel built using Anza's SVM API.

Overview

PayTube is an SVM-based payment channel that enables two or more parties to exchange SOL or SPL tokens off-chain. The channel is initialized by a "VM" (in this case, a Rust program) and, once transactions are complete, the final payment ledger is submitted to the Solana blockchain for settlement.

Key Features

• Off-Chain Transactions: Facilitates rapid, low-cost transactions without the overhead of on-chain processing for each transfer.
• SVM-Based: Leverages the Solana SVM for transaction processing within the channel.
• Settlement to Solana: Ensures final balances are reflected on the Solana blockchain.
• Native SOL and SPL Token Support: Supports transfers of both native SOL and SPL tokens.

Architecture

1. Channel Initialization: A PayTubeChannel is created with a set of keys and an RpcClient.

2. Transaction Processing: PayTubeTransaction objects are processed by the PayTubeChannel::process_paytube_transfers method. This involves:

   • Conversion to SVM-compatible transactions.
   • Execution within the SVM using a TransactionBatchProcessor.
   • Account loading via PayTubeAccountLoader.

3. Settlement: The final ledger is generated by the PayTubeSettler, which creates and submits settlement transactions to the Solana blockchain.

Modules

• src/lib.rs: Main library file, defining the PayTubeChannel and its methods.
• src/loader.rs: Implements the PayTubeAccountLoader for loading accounts into the SVM.
• src/log.rs: Provides logging utilities.
• src/processor.rs: Contains the TransactionBatchProcessor and related functions for processing transactions within the SVM.
• src/settler.rs: Implements the PayTubeSettler for settling the final ledger to the Solana blockchain.
• src/transaction.rs: Defines the PayTubeTransaction structure and related utilities.

Getting Started

Prerequisites

• Rust toolchain
• Solana CLI

Building

cargo build

SVM API