最近 Meta Transactions 一詞開始在中文區塊鏈圈流行，但其實這並不是新名詞，早在 2018 年中就由 Alex Van de Sande 提出的 EIP-1077 帶起討論，而 Austin Thomas Griffith 也緊接著提出他的解決方案 bouncer-proxy ，成了目前許多實作的參考。
那什麼是 Meta Transactions 呢？
在前面的文章中，我們介紹過 LibraSwap，但實際上透過 Libra SPV，我們可用於搭建 Libra 與 Ethereum 之間的橋樑，稱做 LibraBridge。利用 SPV validation 實作跨鏈的代幣交換不是新的創舉，過去有許多項目利用這個方法來橋接兩個不同的鏈上資產，如下。SPV 是一種用於輕節點驗證交易的方法，透過智能合約的協助，我們可以在合約上驗證來自 Libra 的交易。
In the previous article, we explain the concept of the LibraSwap. Next, we will introduce LibraBridge, which can be used to connect Libra with Ethereum by Libra SPV method. The idea to leverage SPV validation to implement cross-chain transfer is not new. It’s already done by several projects listed below. SPV proof is a way for light client to verify if interested transaction happened on the blockchain. With the help of smart contract, Libra SPV proof can be implemented on Ethereum. Namely, we can verify a Libra transaction through smart contract, along with some external information.
In this article, we will introduce LibraSwap, an experimental project to bridge Libra with Ethereum. It aims to implement a minimum viable prototype to fulfill token swap between Libra and Ethereum. There are two reasons why we choose this fun project. On the one hand, we want to learn more on how Libra works. On the other hand, we are familiar with Ethereum blockchain. However, due to the limitation of Libra testnet, we can not deploy and interact with Libra smart contract. We implement a unilateral Libra swap instead of the standard atomic swap.
本文我們將介紹 LibraSwap，這是個實驗性質的專案，旨在實作 MVP 來實現 Libra 與 ETH 之間的 Swap 互換。挑選這個專案的原因，一方面是為了學習 Libra 區塊鏈，另一方面是我們對於以太坊區塊鏈較為熟悉，但是考量目前 Libra 測試鏈上僅能收送交易，尚無法部署合約交易功能，所以這個專案我們將會實作單方向的 Swap 互換。
