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Alex Tan Qui - Blockchains & serverside Swift

Alex Tan Qui - Blockchains & serverside Swift

This was presented at the Swift Usergroup Netherlands. Would you like to speak/present? Visit https://swift.amsterdam for more information.

Alex Tran Qui runs a startup called Katalysis, they use serverside Swift to talk to a blockchain. They use their own libraries on top of the Zewo framework to do so.

Swift Usergroup Netherlands

January 30, 2018
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  1. Blockchain • Peer to peer system secured by Crypto and

    Consensus Algorithms • Enables Transactions between untrusted participants • Underlying technology to Bitcoin, Ethereum
  2. Blockchain node State Engine Consensus Engine Signature based authentication •

    Secured by crypto algorithms (hashing and signing) • State engine stores transactions and possibly code and an execution environment • Proof of Work (PoW), Proof of Stake (PoS), …
  3. Datastore with following properties: • Immutability = “very difficult” to

    change history • Transparency amongst participants • Decentralised • Pseudonymity
  4. Ethereum Smart Contracts • https://ethereum.org • Ethereum Virtual Machine (EVM)

    • Storage of data AND code in the State Engine • EVM language is a JS like language called Solidity
  5. Tendermint • Toolkit for building blockchains • tendermint/ethermint: fully Ethereum

    compatible node, either public or private • https://github.com/tendermint/ethermint/ • https://tendermint.com
  6. libdill • Structured concurrency (coroutine nesting) • Coroutines run on

    a single CPU core • Coroutines must yield control to achieve concurrency • Blocking functions automatically yield
  7. Zewo/Venice func testWakeUpWithChannels() throws { let channel = try Channel<Int>()

    let group = Coroutine.Group() func send(_ value: Int, after delay: Duration) throws { try Coroutine.wakeUp(delay.fromNow()) try channel.send(value, deadline: .never) } try group.addCoroutine(body: { try send(111, after: 30.milliseconds) }) try group.addCoroutine(body: { try send(222, after: 40.milliseconds) }) try group.addCoroutine(body: { try send(333, after: 10.milliseconds) }) try group.addCoroutine(body: { try send(444, after: 20.milliseconds) }) XCTAssert(try channel.receive(deadline: .never) == 333) XCTAssert(try channel.receive(deadline: .never) == 444) XCTAssert(try channel.receive(deadline: .never) == 111) XCTAssert(try channel.receive(deadline: .never) == 222) group.cancel() }
  8. Katalysis libraries Problem: interact with a blockchain node from Swift

    Solutions: • EthereumBlockchain Swift library: Ethereum node compliant JSON-RPC calls, including transaction generation and signing. • ABCISwift library: Tendermint ABCIServer allowing the use of the underlying Consensus Engine.
  9. Ethereum Blockchain library import EthereumKeys import EthereumBlockchain func run() {

    do { let priv = [UInt8](repeating: 0x46, count: 32) let key = EthereumKey(seed:priv)! let ebc = EthereumBlockchain("http://localhost:8545/", key) let to = try? Address(bytes:[UInt8](repeating: 0x35, count: 20)) let tx = TransactionRequest(to: to, value: 100) let txHash = try ebc.transact(tx) print("Transaction hash: \(txHash)") } catch let error { print ("\(error)") } }
  10. ABCISwift library // ABCI apps should comply to the following

    protocol public protocol ABCIApplication { func initChain(_ validators: [Validator]) func info(_ version: String) -> ResponseInfo func echo(_ message: String) -> ResponseEcho func flush() func setOption(_ key: String, _ value: String) -> ResponseSetOption func deliverTx(_ tx: Data) -> Result func checkTx(_ tx: Data) -> Result func query(_ q: Query) -> ResponseQuery func beginBlock(_ hash: Data, _ header: Header) func endBlock(_ height: UInt64) -> ResponseEndBlock func commit() -> Result }
  11. Katalysis libraries Current Status: • Most building blocks (EthereumKey, RPL,

    Crypto algos, …) are already open sourced, work with Swift 4.0.x • Earlier implementation of the EthereumBlockchain libraries (BurrowBlockchain) are open sourced • Open Sourcing EthereumBlockchain and ABCISwift libraries is on the roadmap. Talk to us if you are interested.