Welcome to the second installation in my series on taking the Practical Networked Applications in Rust course, kindly provided by the PingCAP company, where you develop a networked and multithreaded/asynchronous key-value store in the amazing Rust language. You may see my previous post in this series here.

In the previous, and initial, post I implemented the course module of making the fundamental key-value store functionality, based around the Bitcask algorithm, which would only allow for local usage on your own computer. In the second module of my course work, I add networking functionality, dividing the application into a client/server architecture so that clients can connect to servers across the network.

The PingCAP company, makers of the TiDB NewSQL database and the TiKV key-value store, have kindly made publicly available, as well as open-sourced, a set of training courses that they call the "PingCAP Talent Plan". These courses train programmers in writing distributed systems in the Go and Rust languages. They are originally intended by PingCAP to train students, new employees and new contributors to TiDB and TiKV and focus as such on subjects relevant to those projects, but are still appropriate to anyone with an interest in learning to make distributed systems in Go and/or Rust.

Substrate is a framework for making custom blockchains, made available by Berlin based Parity Technologies, who are until now the best known for making the second-most popular (after the official one, Go Ethereum) client for the Ethereum blockchain, also called Parity. Parity Technologies is led by Gavin Wood, one of the inventors of Ethereum and as such one of the true authorities in the blockchain space.

Based on their significant experience in developing the Ethereum blockchain, Parity devised Substrate as a framework/toolkit for those who wish to design their own blockchains as opposed to having to build on top of e.g. Ethereum, while not having to reinvent all the basic building blocks, such as consensus logic. Like the Parity client, Substrate is written in the Rust language.

At the behest of the excellent Quorum Control company, I have carried out my first foray into both Rust and Web Assembly (abbr. Wasm), making a JavaScript/Wasm binding of the Hyperledger Indy Crypto library. The reason behind this undertaking is that Quorum Control (and others) need BLS cryptographic signature verification abilities in JavaScript applications (Web and Node.js), and Indy Crypto provides a solid implementation of this although in the Rust language.

Luckily, there are facilities for converting Rust code into Web Assembly, i.e. the wasm-bindgen tool. While still a fledgling project, it allows us to expose a JavaScript API for the BLS module of Indy Crypto. In practice, this is done by writing a set of Rust functions tagged so that they get exported by the binding generated by wasm-bindgen. Additionally, we produce two variants of the binding: One for Node.js and one for ECMAScript modules aware systems (such as the Webpack bundler), in order for it to work both server side and in the browser.