fcn從頭開始

介紹 (Introduction)

With Web 3.0 and blockchain becoming more mainstream every day, do you know what blockchain is? Do you know its technical advantages and use-cases?

隨著Web 3.0和區(qū)塊鏈每天變得越來越主流，您知道什么是區(qū)塊鏈嗎？ 您知道它的技術(shù)優(yōu)勢和用例嗎？

The goal of this tutorial is to introduce blockchain technology from a technical perspective by building one from scratch.

本教程的目的是通過從頭開始構(gòu)建區(qū)塊鏈技術(shù)，從技術(shù)角度介紹區(qū)塊鏈技術(shù)。

Forget everything you've heard about blockchain from social media. Now, you will build a blockchain system from ground zero to really understand the ins and outs of this peer-to-peer, distributed technology.

忘記您從社交媒體上聽到的有關(guān)區(qū)塊鏈的所有信息。 現(xiàn)在，您將從零開始構(gòu)建一個(gè)區(qū)塊鏈系統(tǒng)，以真正了解這種對(duì)等分布式技術(shù)的來龍去脈。

Afterwards, make your own mind up about its future and advantages. Spoiler alert: you will fall in love with programming blockchain software.

然后，自己決定其未來和優(yōu)勢。 劇透警報(bào)：您將愛上編程區(qū)塊鏈軟件。

怎么樣？ (How?)

You will follow the story of a software developer who is looking to revolutionize his local bar by implementing blockchain technology for its payment system.

您將跟隨一個(gè)軟件開發(fā)人員的故事，該軟件開發(fā)人員希望通過為其支付系統(tǒng)實(shí)施區(qū)塊鏈技術(shù)來革新其本地律師事務(wù)所。

Although blockchain has several undeniable use-cases, at the moment, the number one application is payments. This is because banks are still running on an inefficient, 40 year old infrastructure powered by CSV files and FTP.

盡管區(qū)塊鏈有多個(gè)不可否認(rèn)的用例，但目前，排名第一的應(yīng)用是支付。 這是因?yàn)殂y行仍在使用CSV文件和FTP的低效率，已有40年歷史的基礎(chǔ)架構(gòu)上運(yùn)行。

The story comes with a lot of fun and intriguing facts about the overall blockchain ecosystem and different protocols such as Bitcoin, Ethereum and XRP.

這個(gè)故事帶來了關(guān)于整個(gè)區(qū)塊鏈生態(tài)系統(tǒng)以及比特幣，以太坊和XRP等不同協(xié)議的許多有趣有趣的事實(shí)。

您將在本教程中構(gòu)建，學(xué)習(xí)和做什么？ (What will you build, learn, and do in this tutorial?)

• You'll setup a Go project on your local machine without any prior GoLang experience
  您將在沒有任何GoLang經(jīng)驗(yàn)的情況下在本地計(jì)算機(jī)上設(shè)置Go項(xiàng)目
• You'll generate and distribute your first blockchain tokens
  您將生成并分發(fā)您的第一個(gè)區(qū)塊鏈令牌
• You'll develop a CLI controlled database in Go from scratch
  您將在Go中從頭開始開發(fā)CLI控制的數(shù)據(jù)庫
• You'll find out how few rights users posses in their favourite apps
  您會(huì)發(fā)現(xiàn)在他們最喜歡的應(yīng)用中，有多少位權(quán)限用戶擁有
• You'll discover the blockchain's main value proposition
  您會(huì)發(fā)現(xiàn)區(qū)塊鏈的主要價(jià)值主張
• You'll make your DB immutable using a secure cryptographic hash function
  您將使用安全的加密哈希函數(shù)使數(shù)據(jù)庫不可變

So let's get started and jump into our story.

因此，讓我們開始吧，進(jìn)入我們的故事。

?認(rèn)識(shí)主角安德烈(Andrej)。 (? Meet the protagonist, Andrej.)

Andrej is a bar owner by night and a software developer by day in a small Slovakian town called Bardejov.

Andrej晚上在斯洛伐克的一個(gè)叫Bardejov的小鎮(zhèn)里是酒吧的老板，白天是軟件開發(fā)人員。

Andrej is tired of:

安德烈(Andrej)厭倦了：

• Programming solid, old fashion PHP/Java/Javascript applications

  編程可靠的老式PHP / Java / Javascript應(yīng)用程序

• Forgetting how much money his friends and clients owe him for all the unpaid Friday night vodka shots
  忘記了他的朋友和客戶欠他周五晚上所有未付的伏特加酒花多少錢
• Spending time collecting and counting coins, returning change and generally touching COVID-19-exposed bank bills
  花費(fèi)時(shí)間收集和計(jì)數(shù)硬幣，退還找零錢并且通常接觸COVID-19暴露的銀行票據(jù)
• Maintaining different plastic chips for table football, darts, billiard and poker
  維護(hù)用于桌上足球，Dart，臺(tái)球和撲克的不同塑料芯片

Andrej would love to:

安德烈(Andrej)希望：

• Have a perfect auditable history of the bar's activities and sales to make his bar compliant with tax regulations

  對(duì)酒吧的活動(dòng)和銷售有完善的可審計(jì)歷史，以使其酒吧符合稅收法規(guī)

• Transform his bar into an autonomous, payment-efficient, decentralized and safe environment his customers can trust and profit from

  將他的律師事務(wù)所轉(zhuǎn)變?yōu)榭蛻艨梢孕湃尾闹蝎@利的自治，付款高效，去中心化和安全的環(huán)境

His goal is to write a simple program and keep all the balances of his clients in virtual form.

他的目標(biāo)是編寫一個(gè)簡單的程序，并以虛擬形式保留其客戶的所有余額。

Andrej shares his thoughts here:

安德烈(Andrej)在這里分享他的想法：

"Every new customer will give me cash, and I will credit them an equivalent amount of my digital tokens (coins/cryptocurrency). The tokens will represent a monetary unit within and outside the bar.

“每個(gè)新客戶都會(huì)給我現(xiàn)金， 我會(huì)把他們等值的我的數(shù)字代幣(硬幣/加密貨幣)記入貸方。代幣將代表?xiàng)l形圖內(nèi)外的貨幣單位。

The users will use the tokens for all bar functionalities from paying for drinks, borrowing and lending them to their friends, and playing table tennis, poker and kicker.

用戶將把令牌用于所有酒吧功能，包括支付酒水，將其借貸給朋友，打乒乓球，玩撲克和踢球。

Having a bar powered by blockchain tokens will generate tons of value for my customers. Contrary to my competition and other bars on this street, where the customers only spend money and get a hangover in exchange, my bar customers holding bar's tokens will have shareholders rights.

擁有由區(qū)塊鏈令牌驅(qū)動(dòng)的酒吧將為我的客戶帶來大量價(jià)值。 與我在這條街上的競爭對(duì)手和其他酒吧相反，那里的顧客只花錢并得到宿醉作為交換， 我持有酒吧代幣的酒吧顧客將擁有股東權(quán)利。

Similar to owning a large portion of stocks in a company like Apple or Microsoft, the customers holding these bar tokens will be able to decide how the bar will operate by voting and deciding on:

與在Apple或Microsoft這樣的公司中擁有大量股票類似，持有這些條形碼令牌的客戶將能夠通過投票并決定以下內(nèi)容來決定條形碼的運(yùn)作方式：

• drinks prices
  飲料價(jià)格
• opening hours
  營業(yè)時(shí)間
• new features (TV, Jukebox...)
  新功能(電視，自動(dòng)點(diǎn)唱機(jī)...)
• interior and exterior design
  室內(nèi)和外部設(shè)計(jì)
• profits allocation
  利潤分配
• etc.
  等等

Oh, this will be a programming dream!

哦，這將是一個(gè)編程夢想！

I will call the tokens: The Blockchain Bar tokens, TBB!"

我將這些代幣稱為：區(qū)塊鏈酒吧代幣， TBB！ ”

Now that Andrej has shared his dream, we'll get started.

現(xiàn)在，安德烈(Andrej)分享了他的夢想，我們將開始。

目錄 (Table of Contents)

• Requirements

  要求

• Setup the project

  設(shè)置項(xiàng)目

• 01 | The MVP Database

  01 | MVP數(shù)據(jù)庫

• 02 | Mutating Global DB State

  02 | 突變?nèi)驍?shù)據(jù)庫狀態(tài)

• 03 | Monolithic Event vs Transaction

  03 | 整體事件與交易

• 04 | Humans Are Greedy

  04 | 人類貪婪

• 05 | Why We Need Blockchain

  05 | 為什么我們需要區(qū)塊鏈

• 06 | L'Hash de Immutable

  06 | 不可改變的哈希

• Next steps

  下一步

要求 (Requirements)

Let's dive into our tutorial. I recommend 2+ years of programming experience in Java/PHP/Javascript, or another language similar to Go.

讓我們深入研究我們的教程。 我推薦2年以上Java / PHP / Javascript或類似于Go的語言的編程經(jīng)驗(yàn)。

If you want to get a good quick intro to go, here's a free course that'll get you started.

如果您想快速入門， 這里有一個(gè)免費(fèi)課程 ，可以幫助您入門。

You can also complete the official 17 lectures of A Tour Of Go to get familiar with the language syntax and basic concepts (~20 mins).

您也可以完成A Tour Of Go的 17場官方講座，以熟悉語言語法和基本概念(約20分鐘)。

為什么去？ (Why Go?)

Because like blockchain, it's a fantastic technology for your overall programming career. Go is a trendy language and Go devs are better paid than the average Java/PHP/Javascript positions.

因?yàn)橄駞^(qū)塊鏈一樣，這對(duì)于您的整體編程職業(yè)來說是一種了不起的技術(shù)。 Go是一種流行的語言，Go開發(fā)人員的薪水比平均Java / PHP / Javascript職位高。

Go is optimized for multi-core CPU architecture. You can spawn thousands of light-weight threads (Go-routines) without problems. It's extremely practical for highly parallel and concurrent software such as blockchain networks.

Go針對(duì)多核CPU架構(gòu)進(jìn)行了優(yōu)化。 您可以生成數(shù)千個(gè)輕量級(jí)線程(Go例程)而不會(huì)出現(xiàn)問題。 對(duì)于高度并行和并發(fā)的軟件(例如區(qū)塊鏈網(wǎng)絡(luò))，這是極其實(shí)用的。

By writing your software in Go, you achieve nearly C++ level of performance out of the box without killing yourself for that one time you forgot to free up memory.

通過用Go編寫軟件，您可以立即獲得接近C ++的性能，而不會(huì)因?yàn)橥涐尫艃?nèi)存而喪生。

Go also compiles to binary which makes it very portable.

Go還可以編譯為二進(jìn)制文件，這使其非常易于移植。

設(shè)置項(xiàng)目 (Setup the project)

This article has a dedicated open-sourced Github repository with full source code so you can compile the code and run the program on your own local machine.

本文具有專用的開源Github存儲(chǔ)庫，其中包含完整的源代碼，因此您可以編譯代碼并在自己的本地計(jì)算機(jī)上運(yùn)行程序。

If you get stuck at any chapter or a particular line of code, create a Github Issue in this repository describing your problem and I will help you out ASAP!

如果您陷入任何一章或特定的代碼行中，請(qǐng)?jiān)诖舜鎯?chǔ)庫中創(chuàng)建一個(gè)描述您的問題的Github問題，我會(huì)盡快幫助您！

↓ Visit the Github repository and follow the installation instructions ↓

↓訪問Github存儲(chǔ)庫并按照安裝說明進(jìn)行操作↓

01 | MVP數(shù)據(jù)庫 (01 | The MVP Database)

? git checkout c1_genesis_json

git checkout c1_genesis_json

Andrej mastered relational SQL databases in the 90s. He knows how to make advanced data models and how to optimize the SQL queries.

Andrej在90年代掌握了關(guān)系SQL數(shù)據(jù)庫。 他知道如何制作高級(jí)數(shù)據(jù)模型以及如何優(yōu)化SQL查詢。

It's time for Andrej to catch up with innovation and start building Web 3.0 software.

現(xiàn)在是Andrej趕上創(chuàng)新并開始構(gòu)建Web 3.0軟件的時(shí)候了。

Luckily, after reading "The Lean Startup" book last week, Andrej feels like he shouldn't over-engineer the solution just yet. Hence, he chooses a simple but effective JSON file for the bar's MVP database.

幸運(yùn)的是，安德烈(Andrej)在上周閱讀了《精益創(chuàng)業(yè)》(The Lean Startup)一書后，覺得他現(xiàn)在還不應(yīng)該過度設(shè)計(jì)解決方案。 因此，他為酒吧的MVP數(shù)據(jù)庫選擇了一個(gè)簡單但有效的JSON文件。

In the beginning, there was a primitive centralized database.

最初，有一個(gè)原始的集中式數(shù)據(jù)庫。

📌總結(jié) (📌 Summary)

Blockchain is a database.

區(qū)塊鏈?zhǔn)且粋€(gè)數(shù)據(jù)庫。

用戶1，Andrej (User 1, Andrej)

Monday, March 18.

3月18日，星期一

Andrej generates 1M utility tokens.

Andrej生成1M實(shí)用程序令牌。

In the blockchain world, tokens are units inside the blockchain database. Their real value in dollars or euro fluctuates based on their demand and popularity.

在區(qū)塊鏈?zhǔn)澜缰?#xff0c;令牌是區(qū)塊鏈數(shù)據(jù)庫內(nèi)部的單位。 他們的美元或歐元實(shí)際價(jià)值會(huì)根據(jù)其需求和知名度而波動(dòng)。

Every blockchain has a "Genesis" file. The Genesis file is used to distribute the first tokens to early blockchain participants.

每個(gè)區(qū)塊鏈都有一個(gè)“ Genesis”文件。 Genesis文件用于將第一個(gè)令牌分發(fā)給早期的區(qū)塊鏈參與者。

It all starts with a simple, dummy genesis.json.

這一切都始于一個(gè)簡單的虛擬的genesis.json 。

Andrej creates the file ./database/genesis.json where he defines that The Blockchain Bar's database will have 1M tokens and all of them will belong to Andrej:

Andrej創(chuàng)建文件./database/genesis.json ，他在其中定義Blockchain Bar的數(shù)據(jù)庫將具有1M令牌，并且所有令牌都屬于Andrej：

{"genesis_time": "2019-03-18T00:00:00.000000000Z","chain_id": "the-blockchain-bar-ledger","balances": {"andrej": 1000000} }

The tokens need to have a real "utility", that is a use case. Users should be able to pay with them from day 1!

令牌需要具有真實(shí)的“實(shí)用性”，即用例。 從第一天起，用戶就可以使用他們付款！

Andrej must comply with law regulators (the SEC). It is illegal to issue unregistered security. On the other hand, utility tokens are fine, so right away he prints and sticks a new pricing white p?a?p?e?r? poster on the bar's door.

安德烈(Andrej)必須遵守法律法規(guī)(SEC)。 發(fā)行未注冊的安全性是非法的。 另一方面，實(shí)用程序令牌很好，因此他立即在酒吧的門上打印并粘貼了新的定價(jià)白色p?a?p?e?r?海報(bào)。

Andrej assigns a starting monetary value to his tokens so he can exchange them for euro, dollars, or other fiat currency.

安德烈(Andrej)為代幣分配初始貨幣價(jià)值，以便他可以將其兌換為歐元，美元或其他法定貨幣。

1 TBB token = 1€| Item | Price | | ------------------------- | ------- | | Vodka shot | 1 TBB | | Orange juice | 5 TBB | | Burger | 2 TBB | | Crystal Head Vodka Bottle | 950 TBB |

Andrej also decides he should be getting 100 tokens per day for maintaining the database and having such a brilliant disruptive idea.

Andrej還決定， 他每天應(yīng)該獲得100個(gè)令牌，以維護(hù)數(shù)據(jù)庫并擁有如此出色的破壞性想法。

💡有趣的事實(shí) (💡Fun Facts)

The first genesis Ether (ETH) on Ethereum blockchain was created and distributed to early investors and developers in the same way as Andrej's utility token.以太坊區(qū)塊鏈上的第一個(gè)起源以太(ETH)是以與Andrej的效用代幣相同的方式創(chuàng)建并分發(fā)給早期投資者和開發(fā)商的。 In 2017, during an ICO (initial coin offerings) boom on the Ethereum blockchain network, project founders wrote and presented whitepapers to investors. A whitepaper is a technical document outlining a complex issue and possible solution, meant to educate and elucidate a particular matter. In the world of blockchains, a white paper serves to outline the specifications of how that particular blockchain will look and behave once it is developed.2017年，在以太坊區(qū)塊鏈網(wǎng)絡(luò)上的ICO(初始代幣發(fā)行)熱潮期間，項(xiàng)目創(chuàng)始人撰寫并向投資者介紹了白皮書。 白皮書是一份技術(shù)文檔，概述了一個(gè)復(fù)雜的問題和可能的解決方案，旨在教育和闡明特定問題。 在區(qū)塊鏈領(lǐng)域，白皮書概述了該特定區(qū)塊鏈一旦開發(fā)后將如何表現(xiàn)和行為的規(guī)范。

Blockchain projects raised between €10M to €300M per whitepaper idea.

區(qū)塊鏈項(xiàng)目為每個(gè)白皮書構(gòu)想籌集了1000萬至3億歐元。

in exchange for money (the ICO "funding"), investor names ?would be included in the initial "genesis balances", similar to how Andrej did it. Investors' hopes through an ICO are the genesis coins go up in value and that the teams deliver the outlined blockchain.為了換錢(ICO“資金”)，投資者名稱將包括在初始“創(chuàng)始余額”中，這與Andrej的做法類似。 投資者通過ICO寄予的希望是，創(chuàng)世幣的價(jià)值有所增加，并且團(tuán)隊(duì)可以提供概述的區(qū)塊鏈。 Naturally, not all whitepaper ideas come to fruition. Massive investments lost to unclear or incomplete ideas are why blockchain received negative coverage in the media throughout these ICOs, and why some still considered it a hype. But the underlying blockchain technology is fantastic and useful, as you will learn further in this book. It's just been abused by some bad actors.自然，并非所有白皮書的想法都能實(shí)現(xiàn)。 由于不清楚或不完整的想法而損失的大量投資是為什么區(qū)塊鏈在整個(gè)ICO中受到媒體的負(fù)面報(bào)道，以及為什么有些人仍將其視為炒作。 但是底層的區(qū)塊鏈技術(shù)是神奇而有用的，因?yàn)槟鷮⒃诒緯羞M(jìn)一步學(xué)習(xí)。 它只是被一些壞演員濫用。

📌總結(jié) (📌 Summary)

Blockchain is a database.

區(qū)塊鏈?zhǔn)且粋€(gè)數(shù)據(jù)庫。

The token supply, initial user balances, and global blockchain settings you define in a Genesis file.

您在Genesis文件中定義的令牌供應(yīng)，初始用戶余額和全局區(qū)塊鏈設(shè)置。

02 | 突變?nèi)驍?shù)據(jù)庫狀態(tài) (02 | Mutating Global DB State)

? git checkout c2_db_changes_txt

git checkout c2_db_changes_txt

死黨 (Dead Party)

Monday, March 25.

3月25日，星期一。

After a week of work, the bar facilities are ready to accept tokens. Unfortunately, no one shows up, so Andrej orders three shots of vodka for himself and writes the database changes on a piece of paper:

經(jīng)過一周的工作，酒吧設(shè)施已準(zhǔn)備就緒，可以接受代幣。 不幸的是，沒有人出現(xiàn)，因此安德烈(Andrej)為自己訂購了三杯伏特加酒，并將數(shù)據(jù)庫更改寫在紙上：

andrej-3; // 3 shots of vodka andrej+3; // technically purchasing from his own bar andrej+700; // Reward for a week of work (7x100 per day)

To avoid recalculating the latest state of each customer's balance, Andrej creates a ./database/state.json file storing the balances in an aggregated format.

為了避免重新計(jì)算每個(gè)客戶余額的最新狀態(tài)，Andrej創(chuàng)建了一個(gè)./database/state.json文件，以匯總格式存儲(chǔ)了余額。

New DB state:

新的數(shù)據(jù)庫狀態(tài)：

{"balances": {"andrej": 1000700} }

BabaYaga的獎(jiǎng)勵(lì) (Bonus for BabaYaga)

Tuesday, March 26.

3月26日，星期二。

To bring traffic to his bar, Andrej announces an exclusive 100% bonus for everyone who purchases the TBB tokens in the next 24 hours.

為了將流量帶入他的酒吧，Andrej宣布了在接下來的24小時(shí)內(nèi)向購買TBB代幣的每個(gè)人提供100％的獨(dú)家獎(jiǎng)勵(lì)。

Bing! He gets his first customer called BabaYaga. BabaYaga pre-purchases 1000€ worth of tokens, and to celebrate, she immediately spends 1 TBB for a vodka shot. She has a drinking problem.

！ 他得到了第一個(gè)客戶BabaYaga 。 BabaYaga預(yù)購了價(jià)值1000歐元的代幣，為了慶祝，她立即花了1湯匙TBB喝了伏特加。 她有飲酒問題。

DB transactions written on a piece of paper:

DB事務(wù)寫在紙上：

andrej-2000; // transfer to BabaYaga babayaga+2000; // pre-purchase with 100% bonus babayaga-1; andrej+1; andrej+100; // 1 day of sun coming up

New DB state:

新的數(shù)據(jù)庫狀態(tài)：

{"balances": {"andrej": 998801,"babayaga": 1999} }

💡有趣的事實(shí) (💡Fun Facts)

Blockchain ICO (initial coin offerings based on whitepapers) projects often distribute the genesis tokens with different bonuses, depending on how many of them you buy and how early you do it. Teams offer, on average, 10-40% bonuses to early "participants".區(qū)塊鏈ICO(基于白皮書的初始代幣發(fā)行)項(xiàng)目通常會(huì)分配具有不同獎(jiǎng)勵(lì)的創(chuàng)世代幣，具體取決于您購買了多少代幣以及您有多早完成了代幣。 團(tuán)隊(duì)平均為早期的“參與者”提供10-40％的獎(jiǎng)金。 The word "investor" is avoided, so law regulators won't consider the tokens as a security. Projects would reason their main product, blockchain tokens, function as "flying, loyalty points."避免使用“投資者”這個(gè)詞，因此法律監(jiān)管機(jī)構(gòu)不會(huì)將代幣視為證券。 項(xiàng)目會(huì)推論其主要產(chǎn)品區(qū)塊鏈令牌的作用是“飛行，忠誠度積分”。 The "participants" later made even 1000% on their investment selling to the public through an exchange several months later.幾個(gè)月后，“參與者”甚至通過交易所向公眾出售其投資的1000％。

📌總結(jié) (📌Summary)

Blockchain is a database.

區(qū)塊鏈?zhǔn)且粋€(gè)數(shù)據(jù)庫。

The token supply, initial user balances, and global blockchain settings you define in a Genesis file.

您在Genesis文件中定義的令牌供應(yīng)，初始用戶余額和全局區(qū)塊鏈設(shè)置。

The Genesis balances indicate what was the original blockchain state and are never updated afterwards.

創(chuàng)世余額表明最初的區(qū)塊鏈狀態(tài)是什么，以后再也不會(huì)更新。

The database state changes are called Transactions (TX).

數(shù)據(jù)庫狀態(tài)更改稱為事務(wù)(TX)。

03 | 整體事件與交易 (03 | Monolithic Event vs Transaction)

? git checkout c3_state_blockchain_component

git checkout c3_state_blockchain_component

Developers used to event-sourcing architecture must have immediately recognized the familiar principles behind transactions. They are correct.

習(xí)慣了事件采購架構(gòu)的開發(fā)人員必須立即認(rèn)識(shí)到交易背后的熟悉原理。 他們是正確的。

Blockchain transactions represent a series of events, and the database is a final aggregated, calculated state after replaying all the transactions in a specific sequence.

區(qū)塊鏈交易代表一系列事件，數(shù)據(jù)庫是按特定順序重播所有交易后的最終匯總，計(jì)算狀態(tài)。

安德烈(Andrej)編程 (Andrej Programming)

Tuesday evening, March 26.

3月26日，星期二晚上。

It's a relaxing Tuesday evening for Andrej. Celebrating his first client, he decides to play some Starcraft and clean up his local development machine by removing some old pictures.

這對(duì)安德烈(Andrej)來說是個(gè)輕松的星期二晚上。 為了慶祝他的第一個(gè)客戶，他決定玩一些《 星際爭霸》，并通過刪除一些舊照片來清理自己的本地開發(fā)機(jī)器。

Unfortunately, he prematurely pressed enter when typing a removal command path in terminal sudo rm -rf /. Oops.

不幸的是，他在終端sudo rm -rf /鍵入刪除命令路徑時(shí)過早按下Enter鍵。 哎呀。

All his files, including the bar's genesis.json and state.json are gone.

他的所有文件，包括酒吧的genesis.json和state.json都不見了。

Andrej, being a senior developer, repeatedly shouted some f* words very loudly for a few seconds, but he didn't panic!

作為高級(jí)開發(fā)人員的安德烈(Andrej)反復(fù)大聲喊了幾句f *字，但他并沒有驚慌！

While he didn't have a backup, he had something better — a piece of paper with all the database transactions. The only thing he needs to do is replay all the transactions one by one, and his database state will get recovered.

雖然他沒有備份，但他有更好的東西–一張紙上所有的數(shù)據(jù)庫事務(wù)。 他唯一需要做的就是一個(gè)接一個(gè)地重放所有事務(wù)，他的數(shù)據(jù)庫狀態(tài)將恢復(fù)。

Impressed by the advantages of event-based architecture, he decides to extend his MVP database solution. Every bar's activity, such as individual drink purchases, MUST be recorded inside the blockchain database.

他對(duì)基于事件的體系結(jié)構(gòu)的優(yōu)勢印象深刻，因此決定擴(kuò)展其MVP數(shù)據(jù)庫解決方案。 每個(gè)酒吧的活動(dòng)，例如個(gè)人飲料購買，都必須記錄在區(qū)塊鏈數(shù)據(jù)庫中。

Each customer will be represented in DB using an Account Struct:

每個(gè)客戶將使用帳戶結(jié)構(gòu)在數(shù)據(jù)庫中代表：

type Account string

Each Transaction (TX - a database change) will have the following four attributes: from, to, value and data.

每個(gè)事務(wù) (TX-數(shù)據(jù)庫更改)將具有以下四個(gè)屬性： 從，到，值和數(shù)據(jù) 。

The data attribute with one possible value (reward) captures Andrej's bonus for inventing the blockchain and increases the initial TBB tokens total supply artificially (inflation).

具有一個(gè)可能值( 獎(jiǎng)勵(lì) )的數(shù)據(jù)屬性捕獲了安德烈(Andrej)發(fā)明區(qū)塊鏈的獎(jiǎng)金，并人為地增加了初始TBB代幣的總供應(yīng)量(通貨膨脹)。

type Tx struct {From Account `json:"from"`To Account `json:"to"`Value uint `json:"value"`Data string `json:"data"` }func (t Tx) IsReward() bool {return t.Data == "reward" }

The Genesis DB will remain a JSON file:

Genesis數(shù)據(jù)庫將保留為JSON文件：

{"genesis_time": "2019-03-18T00:00:00.000000000Z","chain_id": "the-blockchain-bar-ledger","balances": {"andrej": 1000000} }

All the transactions, previously written on a piece of paper, will be stored in a local text-file database called tx.db, serialized in JSON format and separated by line-break character:

所有以前寫在紙上的交易都將存儲(chǔ)在一個(gè)名為tx.db的本地文本文件數(shù)據(jù)庫中，該數(shù)據(jù)庫以JSON格式序列化并以換行符分隔：

{"from":"andrej","to":"andrej","value":3,"data":""} {"from":"andrej","to":"andrej","value":700,"data":"reward"} {"from":"andrej","to":"babayaga","value":2000,"data":""} {"from":"andrej","to":"andrej","value":100,"data":"reward"} {"from":"babayaga","to":"andrej","value":1,"data":""}

The most crucial database component encapsulating all the business logic will be State:

封裝所有業(yè)務(wù)邏輯的最關(guān)鍵的數(shù)據(jù)庫組件將是State ：

type State struct {Balances map[Account]uinttxMempool []TxdbFile *os.File }

The State struct will know about all user balances and who transferred TBB tokens to whom, and how many were transferred.

State結(jié)構(gòu)將了解所有用戶余額以及誰將TBB令牌轉(zhuǎn)讓給了誰，以及轉(zhuǎn)讓了多少。

It's constructed by reading the initial user balances from genesis.json file:

通過從genesis.json文件中讀取初始用戶余額來genesis.json ：

func NewStateFromDisk() (*State, error) {// get current working directorycwd, err := os.Getwd()if err != nil {return nil, err}genFilePath := filepath.Join(cwd, "database", "genesis.json")gen, err := loadGenesis(genFilePath)if err != nil {return nil, err}balances := make(map[Account]uint)for account, balance := range gen.Balances {balances[account] = balance}

Afterwards, the genesis State balances are updated by sequentially replaying all the database events from tx.db:

然后，通過順序重播tx.db所有數(shù)據(jù)庫事件來更新創(chuàng)始State余額：

txDbFilePath := filepath.Join(cwd, "database", "tx.db")f, err := os.OpenFile(txDbFilePath, os.O_APPEND|os.O_RDWR, 0600)if err != nil {return nil, err}scanner := bufio.NewScanner(f)state := &State{balances, make([]Tx, 0), f}// Iterate over each the tx.db file's linefor scanner.Scan() {if err := scanner.Err(); err != nil {return nil, err}// Convert JSON encoded TX into an object (struct)var tx Txjson.Unmarshal(scanner.Bytes(), &tx)// Rebuild the state (user balances),// as a series of eventsif err := state.apply(tx); err != nil {return nil, err}}return state, nil }

The State component is responsible for:

State部門負(fù)責(zé)：

• Adding new transactions to Mempool

  向 Mempool 添加新交易

• Validating transactions against the current State (sufficient sender balance)

  根據(jù)當(dāng)前狀態(tài)驗(yàn)證交易(發(fā)件人余額充足)

• Changing the state

  改變狀態(tài)

• Persisting transactions to disk

  將事務(wù)持久化到磁盤

• Calculating accounts balances by replaying all transactions since Genesis in a sequence

  通過重播自創(chuàng)世紀(jì)以來的所有交易來計(jì)算帳戶余額

Adding new transactions to Mempool:

向 Mempool 添加新交易：

func (s *State) Add(tx Tx) error {if err := s.apply(tx); err != nil {return err}s.txMempool = append(s.txMempool, tx)return nil }

Persisting the transactions to disk:

將事務(wù)持久化到磁盤：

func (s *State) Persist() error {// Make a copy of mempool because the s.txMempool will be modified// in the loop belowmempool := make([]Tx, len(s.txMempool))copy(mempool, s.txMempool)for i := 0; i < len(mempool); i++ {txJson, err := json.Marshal(s.txMempool[i])if err != nil {return err}if _, err = s.dbFile.Write(append(txJson, '\n')); err != nil {return err}// Remove the TX written to a file from the mempool// Yes... this particular Go syntax is a bit weirds.txMempool = append(s.txMempool[:i], s.txMempool[i+1:]...)}return nil }

Changing, Validating the state:

更改，驗(yàn)證狀態(tài)：

func (s *State) apply(tx Tx) error {if tx.IsReward() {s.Balances[tx.To] += tx.Valuereturn nil}if tx.Value > s.Balances[tx.From] {return fmt.Errorf("insufficient balance")}s.Balances[tx.From] -= tx.Values.Balances[tx.To] += tx.Valuereturn nil }

構(gòu)建命令行界面(CLI) (Building a Command-Line-Interface (CLI))

Tuesday evening, March 26.

3月26日，星期二晚上。

Andrej wants to have a convenient way to add new transactions to his DB and list the latest balances of his customers. Because Go programs compile to binary, he builds a CLI for his program.

Andrej希望有一種方便的方法將新交易添加到他的數(shù)據(jù)庫并列出其客戶的最新余額。 由于Go程序會(huì)編譯為二進(jìn)制文件，因此他會(huì)為其程序構(gòu)建一個(gè)CLI。

The easiest way to develop CLI based programs in Go is by using the third party github.com/spf13/cobra library.

在Go中開發(fā)基于CLI的程序的最簡單方法是使用第三方github.com/spf13/cobra庫。

Andrej initializes Go's built-in dependency manager for his project, called go modules:

Andrej為其項(xiàng)目初始化Go的內(nèi)置依賴項(xiàng)管理器，稱為go modules ：

? cd $GOPATH/src/github.com/web3coach/the-blockchain-way-of-programming-newsletter-edition

cd $GOPATH/src/github.com/web3coach/the-blockchain-way-of-programming-newsletter-edition

? go mod init github.com/web3coach/the-blockchain-way-of-programming-newsletter-edition

go mod init github.com/web3coach/the-blockchain-way-of-programming-newsletter-edition

The Go modules command will automatically fetch any library you reference within your Go files.

Go modules命令將自動(dòng)獲取您在Go文件中引用的任何庫。

Andrej creates a new directory called: cmd with a subdirectory tbb:

Andrej創(chuàng)建了一個(gè)新目錄： cmd和一個(gè)子目錄tbb ：

?mkdir -p ./cmd/tbb

mkdir -p ./cmd/tbb

Inside he creates a main.go file, serving as the program's CLI entry point:

在其中，他創(chuàng)建了一個(gè)main.go文件，用作該程序的CLI入口點(diǎn)：

package mainimport ("github.com/spf13/cobra""os""fmt" )func main() {var tbbCmd = &cobra.Command{Use: "tbb",Short: "The Blockchain Bar CLI",Run: func(cmd *cobra.Command, args []string) {},}err := tbbCmd.Execute()if err != nil {fmt.Fprintln(os.Stderr, err)os.Exit(1)} }

The Go programs are compiled using the install cmd:? go install ./cmd/tbb/...

Go程序使用install cmd編譯： go install ./cmd/tbb/...

go: finding github.com/spf13/cobra v1.0.0 go: downloading github.com/spf13/cobra v1.0.0 go: extracting github.com/spf13/cobra v1.0.0

Go will detect missing libraries and automatically fetch them before compiling the program. Depending on your $GOPATH the resulting program will be saved in the $GOPATH/bin folder.

Go將檢測缺少的庫并在編譯程序之前自動(dòng)獲取它們。 根據(jù)您的$GOPATH ，結(jié)果程序?qū)⒈４嬖?GOPATH/bin文件夾中。

?echo $GOPATH

echo $GOPATH

/home/web3coach/go

?which tbb

which tbb

/home/web3coach/go/bin/tbb

You can run tbb from your terminal now, but it will not do anything because the Run function inside the main.go file is empty.

您現(xiàn)在可以從終端運(yùn)行tbb ，但由于main.go文件中的Run函數(shù)為空，因此它不會(huì)執(zhí)行任何操作。

The first thing Andrej needs is versioning support for his tbb CLI program.

Andrej首先需要的是對(duì)其tbb CLI程序的版本控制。

Next to the main.go file, he creates a version.go command:

在main.go文件旁邊，他創(chuàng)建了version.go命令：

package mainimport ("fmt""github.com/spf13/cobra" )const Major = "0" const Minor = "1" const Fix = "0" const Verbal = "TX Add && Balances List"var versionCmd = &cobra.Command{Use: "version",Short: "Describes version.",Run: func(cmd *cobra.Command, args []string) {fmt.Printf("Version: %s.%s.%s-beta %s", Major, Minor, Fix, Verbal)}, }

Compiles and runs it:? go install ./cmd/tbb/...? tbb version

編譯并運(yùn)行它：? go install ./cmd/tbb/... tbb version

Version: 0.1.0-beta TX Add && Balances List

Version: 0.1.0-beta TX Add && Balances List

Perfect.

完善。

Identically to the version.go file, he creates a balances.go file:

與version.go文件相同，他創(chuàng)建了balances.go文件：

func balancesCmd() *cobra.Command {var balancesCmd = &cobra.Command{Use: "balances",Short: "Interact with balances (list...).",PreRunE: func(cmd *cobra.Command, args []string) error {return incorrectUsageErr()},Run: func(cmd *cobra.Command, args []string) {},}balancesCmd.AddCommand(balancesListCmd)return balancesCmd }

The balances command will be responsible for loading the latest DB State and printing it to the standard output:

balances命令將負(fù)責(zé)加載最新的數(shù)據(jù)庫狀態(tài)并將其打印到標(biāo)準(zhǔn)輸出：

var balancesListCmd = &cobra.Command{Use: "list",Short: "Lists all balances.",Run: func(cmd *cobra.Command, args []string) {state, err := database.NewStateFromDisk()if err != nil {fmt.Fprintln(os.Stderr, err)os.Exit(1)}defer state.Close()fmt.Println("Accounts balances:")fmt.Println("__________________")fmt.Println("")for account, balance := range state.Balances {fmt.Println(fmt.Sprintf("%s: %d", account, balance))}}, }

Andrej verifies if the cmd works as expected. It should print the exact balances defined in the Genesis file because the tx.db file is still empty.

Andrej驗(yàn)證cmd是否按預(yù)期工作。 由于tx.db文件仍然為空，因此應(yīng)打印在Genesis文件中定義的確切余額。

? go install ./cmd/tbb/...

? go install ./cmd/tbb/...

? tbb balances list

tbb balances list

Accounts balances: __________________ andrej: 1000000

Works well! Now he only needs a cmd for recording the bar's activity.

效果很好！ 現(xiàn)在，他只需要一個(gè)cmd即可記錄酒吧的活動(dòng)。

Andrej creates ./cmd/tbb/tx.go cmd:

Andrej創(chuàng)建./cmd/tbb/tx.go cmd：

func txCmd() *cobra.Command {var txsCmd = &cobra.Command{Use: "tx",Short: "Interact with txs (add...).",PreRunE: func(cmd *cobra.Command, args []string) error {return incorrectUsageErr()},Run: func(cmd *cobra.Command, args []string) {},}txsCmd.AddCommand(txAddCmd())return txsCmd }

The tbb tx add cmd uses State.Add(tx) function for persisting the bar's events into the file system:

tbb tx add cmd使用State.Add(tx)函數(shù)將欄的事件持久化到文件系統(tǒng)中：

func txAddCmd() *cobra.Command {var cmd = &cobra.Command{Use: "add",Short: "Adds new TX to database.",Run: func(cmd *cobra.Command, args []string) {from, _ := cmd.Flags().GetString(flagFrom)to, _ := cmd.Flags().GetString(flagTo)value, _ := cmd.Flags().GetUint(flagValue)fromAcc := database.NewAccount(from)toAcc := database.NewAccount(to)tx := database.NewTx(fromAcc, toAcc, value, "")state, err := database.NewStateFromDisk()if err != nil {fmt.Fprintln(os.Stderr, err)os.Exit(1)}// defer means, at the end of this function execution,// execute the following statement (close DB file with all TXs)defer state.Close()// Add the TX to an in-memory array (pool)err = state.Add(tx)if err != nil {fmt.Fprintln(os.Stderr, err)os.Exit(1)}// Flush the mempool TXs to diskerr = state.Persist()if err != nil {fmt.Fprintln(os.Stderr, err)os.Exit(1)}fmt.Println("TX successfully added to the ledger.")},}

The tbb tx add cmd has 3 mandatory flags: --from, --to and --value.

tbb tx add cmd具有3個(gè)強(qiáng)制性標(biāo)志： --from --to ，-- --to和--value 。

cmd.Flags().String(flagFrom, "", "From what account to send tokens") cmd.MarkFlagRequired(flagFrom)cmd.Flags().String(flagTo, "", "To what account to send tokens") cmd.MarkFlagRequired(flagTo)cmd.Flags().Uint(flagValue, 0, "How many tokens to send") cmd.MarkFlagRequired(flagValue)return cmd

The CLI is done!

CLI已完成！

Andrej migrates all transactions from paper to his new DB:

Andrej將所有交易從紙本遷移到他的新數(shù)據(jù)庫：

? tbb tx add --from=andrej --to=andrej --value=3

tbb tx add --from=andrej --to=andrej --value=3

?tbb tx add --from=andrej --to=andrej --value=700

tbb tx add --from=andrej --to=andrej --value=700

?tbb tx add --from=babayaga --to=andrej --value=2000

tbb tx add --from=babayaga --to=andrej --value=2000

?tbb tx add --from=andrej --to=andrej --value=100 --data=reward

tbb tx add --from=andrej --to=andrej --value=100 --data=reward

?tbb tx add --from=babayaga --to=andrej --value=1

tbb tx add --from=babayaga --to=andrej --value=1

Read all TXs from disk and calculate the latest state:

從磁盤讀取所有TX，并計(jì)算最新狀態(tài)：

? tbb balances list

tbb balances list

Accounts balances: __________________ andrej: 998801 babayaga: 1999

Bar data successfully restored! Phew, what a night!

條數(shù)據(jù)成功恢復(fù)！ ew，真是個(gè)晚上！

關(guān)于Cobra CLI庫 (About the Cobra CLI library)

The good thing about the Cobra lib for CLI programming is the additional features it comes with. For example, you can now run: tbb help cmd and it will print out all TBB registered sub-commands with instructions on how to use them.

關(guān)于Cobra lib進(jìn)行CLI編程的好處是它附帶的其他功能。 例如，您現(xiàn)在可以運(yùn)行： tbb help cmd，它將打印出所有TBB注冊的子命令以及有關(guān)如何使用它們的說明。

tbb helpThe Blockchain Bar CLIUsage:tbb [flags]tbb [command]Available Commands:balances Interact with balances (list...).help Help about any commandtx Interact with txs (add...).version Describes version.Flags:-h, --help help for tbbUse "tbb [command] --help" for more information about a command.

💡有趣的事實(shí) (💡Fun Facts)

Accidentally losing customers' data is a standard Saturday in the corporate world these days. Blockchain fixes this by decentralizing the data storage.這些天，意外丟失客戶數(shù)據(jù)是企業(yè)界的一個(gè)標(biāo)準(zhǔn)星期六。 區(qū)塊鏈通過分散數(shù)據(jù)存儲(chǔ)來解決此問題。

The trick Andrej baked into the program by skipping balance verification for TXs marked as rewards. Bitcoin and Ethereum work in the same way. The balance of the Account who mined a block increases out of the blue as a subject of total tokens supply inflation affecting the whole chain. The total supply of bitcoins is capped at 21M BTC. You will learn more about "mining" and "blocks" in chapters 7 and 10.

安德烈(Andrej)通過跳過標(biāo)記為獎(jiǎng)勵(lì)的TX的余額驗(yàn)證來進(jìn)入程序。 比特幣和以太坊以相同的方式工作。 開采區(qū)塊的賬戶余額突然增加，這是總代幣供應(yīng)膨脹影響整個(gè)鏈條的主題。 比特幣的總供應(yīng)量上限為2100萬比特幣。 您將在第7章和第10章中了解有關(guān)“采礦”和“障礙物”的更多信息。

The components State and Mempool are not unique to this program. Andrej chose the names and designs to match a simplified go-Ethereum, model so you have a glance inside the core Ethereum source code.

State和Mempool組件不是此程序唯一的。 Andrej選擇了名稱和設(shè)計(jì)來匹配簡化的以太坊模型，因此您可以一窺以太坊核心源代碼。

📌總結(jié) (📌 Summary)

Blockchain is a database.

區(qū)塊鏈?zhǔn)且粋€(gè)數(shù)據(jù)庫。

The token supply, initial user balances, and global blockchain settings are defined in a Genesis file.

代幣供應(yīng)，初始用戶余額和全局區(qū)塊鏈設(shè)置在Genesis文件中定義。

The Genesis balances indicate what the original blockchain state was and are never updated afterwards.

創(chuàng)世余額表明最初的區(qū)塊鏈狀態(tài)是什么，以后再也不會(huì)更新。

The database state changes are called Transactions (TX).

數(shù)據(jù)庫狀態(tài)更改稱為事務(wù)(TX)。

Transactions are old fashion Events representing actions within the system.

事務(wù)是老式的事件，代表系統(tǒng)內(nèi)的動(dòng)作。

?學(xué)習(xí)代碼 (? Study Code)

Commit: 5d4b0b

提交： 5d4b0b

Let's talk about greed.

讓我們談?wù)勜澙贰?

04 | 人類貪婪 (04 | Humans Are Greedy)

? git checkout c4_caesar_transfer

git checkout c4_caesar_transfer

典型的商業(yè)貪婪 (Typical business greediness)

Wednesday, March 27.

3月27日，星期三。

BabaYaga invested a bit too much. She forgot her flat rent payment was around the corner, and she doesn't have the money. BabaYaga calls her flat owner, Caesar.

BabaYaga投入了太多。 她忘記了即將支付的固定租金，而且她沒有錢。 BabaYaga打電話給她的單位老板凱撒(Caesar)。

BabaYaga: Hey Caesar, I am sorry, but I don't have the cash to pay you the rent this month…

BabaYaga：凱撒，很抱歉，但我沒有現(xiàn)金支付您本月的租金…

Caesar: Why not?

凱撒：為什么不呢？

BabaYaga: The Blockchain Bar ICO offered a massive bonus, and I purchased 2000€ worth of tokens for just 1000€. It was a great deal!

BabaYaga：區(qū)塊鏈酒吧ICO提供了巨大的獎(jiǎng)金，我以1000歐元的價(jià)格購買了價(jià)值2000歐元的代幣。 真是太好了！

Caesar: What the heck are you talking about? What is an ICO? What on earth are tokens? Can you pay me in some other way?

凱撒：你到底在說什么？ 什么是ICO？ 代幣到底是什么？ 你可以用其他方式付我錢嗎？

BabaYaga: Oh, not again. I can give you 1000 TBB tokens worth 1000€, and you can use them in the bar to pay for your drinks! Let me call the bar owner, Andrej, and make the transfer!

BabaYaga：哦，不再。 我可以給您1000枚價(jià)值1000歐元的TBB代幣，您可以在酒吧使用它們來購買飲品！ 讓我打電話給酒吧老板安德烈(Andrej)，進(jìn)行轉(zhuǎn)讓！

Caesar: All right... I will take it.

凱撒：好吧...我會(huì)接受的。

Andrej performs the transfer, but decides to charge an extra 50 TBB tokens for his troubles. He doesn't want to, BUT the bar shareholders who invested in him a few years ago are forcing him to generate profit as soon as possible.

安德烈(Andrej)進(jìn)行了轉(zhuǎn)讓， 但決定為自己的麻煩收取額外的50枚TBB代幣。 他不想，但幾年前投資他的律師大股東卻強(qiáng)迫他盡快創(chuàng)造利潤。

BabaYaga won't notice this relatively small fee most likely anyway, Andrej tells himself. In the end, only he has the DB access.

無論如何，BabaYaga最有可能不會(huì)注意到這筆相對(duì)較小的費(fèi)用，Andrej告訴自己。 最后，只有他具有數(shù)據(jù)庫訪問權(quán)限。

// Rent payment

//租金支付

?tbb tx add --from=babayaga --to=caesar --value=1000

tbb tx add --from=babayaga --to=caesar --value=1000

// hidden fee charge

//隱藏費(fèi)用

? tbb tx add --from=babayaga --to=andrej --value=50

tbb tx add --from=babayaga --to=andrej --value=50

// new reward for another day of maintaining the DB

//維護(hù)數(shù)據(jù)庫另一天的新獎(jiǎng)勵(lì)

? tbb tx add --from=andrej --to=andrej --value=100 --data=reward

tbb tx add --from=andrej --to=andrej --value=100 --data=reward

💡有趣的事實(shí) (💡Fun Facts)

The number one blockchain use-case is banking. Many blockchain projects aim to optimize the domestic and international exchange of money across different currency corridors (XRP).區(qū)塊鏈的第一個(gè)用例是銀行業(yè)務(wù)。 許多區(qū)塊鏈項(xiàng)目旨在優(yōu)化跨不同貨幣通道(XRP)的國內(nèi)和國際貨幣交換。 Other projects focus on freedom and self-sovereign identity (SSI) - a digital movement that recognizes an individual should own and control their identity and money without the intervening administrative authorities or other centralized intermediaries. SSI allows people to interact in the digital world with the same freedom and capacity for trust as they do in the offline world. (Bitcoin / Ethereum)其他項(xiàng)目則側(cè)重于自由和自我主權(quán)(SSI)-一種數(shù)字運(yùn)動(dòng)，它認(rèn)識(shí)到個(gè)人應(yīng)擁有并控制自己的身份和金錢，而無需干預(yù)行政當(dāng)局或其他中央中介機(jī)構(gòu)。 SSI允許人們在數(shù)字世界中以與離線世界相同的自由度和信任度進(jìn)行交互。 (比特幣/以太坊) Here are few fun facts why blockchain is a perfect fit for replacing your bank's current banking infrastructure.以下是一些有趣的事實(shí)，為什么區(qū)塊鏈非常適合替代您銀行現(xiàn)有的銀行基礎(chǔ)設(shè)施。 The good thing about virtual tokens is their fungibility - i.e., their ability to be traded, with each unit being as usable as the next. Performing a transfer from account to account can be done by simply changing the database state. Cryptocurrencies are tradeable 24/7.虛擬代幣的優(yōu)點(diǎn)在于它們的可替代性-即它們的交易能力，每個(gè)單位都可以使用下一個(gè)單位。 只需更改數(shù)據(jù)庫狀態(tài)即可完成帳戶之間的轉(zhuǎn)移。 加密貨幣可以24/7交易。 You can't trade stocks directly. You need to go through a broker who takes part a percentage of the total transaction as a fee (1-3% to 7% average yearly profit).您不能直接交易股票。 您需要經(jīng)過一個(gè)經(jīng)紀(jì)人，該經(jīng)紀(jì)人作為費(fèi)用收取總交易額的一部分(平均年利潤的1-3％至7％)。

An international bank transfer takes between 3-10 business days and can cost as much 5% of the transferred value! If you’re sending $10,000, you may have to pay up to $500. The technology behind for the last 40 years? FTP + CSV files.

國際銀行轉(zhuǎn)賬需要3到10個(gè)工作日，并且可能要花費(fèi)轉(zhuǎn)賬金額的5％！ 如果您要匯款$ 10,000，則可能最多需要支付$ 500。 過去40年中落后的技術(shù)？ FTP + CSV文件。

Do you think the stock market is fair? Banks, indexes, and stocks are highly centralized and controlled by governments and private Wall Street groups. Free market? Wall Street controls how much can prices jump/fall in a single day.您認(rèn)為股市公平嗎？ 銀行，指數(shù)和股票高度集中，并由政府和華爾街私人集團(tuán)控制。 自由市場？ 華爾街控制價(jià)格在一天之內(nèi)可以上漲/下跌多少。 As an example, Wall Street halted the trading of "S&P 500 Index" after a 7% drop to protect their investors and hedge funds from losing money from people selling their stocks during March 2020 after COVID news. Afterward, the FED printed trillions of dollars for themselves to support the stock price. If you are a developer who likes to save money and avoid debt, your savings just lost value overnight by a yet unknown percentage.例如，華爾街在下跌7％之后停止了“標(biāo)準(zhǔn)普爾500指數(shù)”的交易，以保護(hù)其投資者和對(duì)沖基金避免在2020年3月COVID消息傳出后拋售股票的人蒙受損失。 后來，美聯(lián)儲(chǔ)自己印制了數(shù)萬億美元來支撐股價(jià)。 如果您是喜歡節(jié)省金錢并避免債務(wù)的開發(fā)人員，那么您的儲(chǔ)蓄在一夜之間損失了價(jià)值，但未知的百分比。 Many countries are going into negative yields, an unexplored territory with unknown consequences. What does this mean? Soon you will have to pay the bank to keep your savings. Inflation at its best. You are being forced to spend your money to support a system you don't control.許多國家正處于負(fù)收益狀態(tài)，這是一個(gè)尚未開發(fā)的領(lǐng)域，后果不明。 這是什么意思？ 很快，您將不得不向銀行付款以保留您的積蓄。 通貨膨脹處于最佳狀態(tài)。 您被迫花錢支持不受控制的系統(tǒng)。

?學(xué)習(xí)代碼 (? Study Code)

Commit: 00d6ed

提交： 00d6ed

05 | 為什么我們需要區(qū)塊鏈 (05 | Why We Need Blockchain)

? git checkout c5_broken_trust

git checkout c5_broken_trust

BabaYaga尋求正義 (BabaYaga Seeks Justice)

Thursday, March 28.

3月28日，星期四。

BabaYaga enters the bar for her birthday.

BabaYaga生日那天進(jìn)入酒吧。

BabaYaga: Hey, Andrej! Today is my birthday! Get me your most expensive bottle!

BabaYaga：嗨，安德烈！ 今天是我的生日！ 給我你最貴的瓶子！

Andrej: Happy birthday! Here you go: Crystal Head Vodka. But you need to purchase one additional TBB token. The bottle costs 950 tokens, and your balance is 949.

安德烈：生日快樂！ 在這里，您去了：水晶頭伏特加酒。 但是您需要另外購買一個(gè)TBB令牌。 該瓶子的價(jià)格為950個(gè)令牌，您的余額為949。

BabaYaga: What?! My balance is supposed to be 999 TBB!

BabaYaga：什么？！ 我的余額應(yīng)該是999 TBB！

Andrej: The funds transfer to Caesar you requested last week cost you 50 tokens.

安德烈(Andrej)：您上周向凱撒(Caesar)進(jìn)行的資金轉(zhuǎn)帳花費(fèi)了您50個(gè)令牌。

BabaYaga: This is unacceptable! I would never agree to such a high fee. You can't do this, Andrej. I trusted your system, but you are as unreliable as every other business owner. Things must change!

BabaYaga：這是不可接受的！ 我永遠(yuǎn)不會(huì)同意這么高的費(fèi)用。 你不能做到這一點(diǎn)，安德烈(Andrej)。 我信任您的系統(tǒng)，但是您和其他企業(yè)主一樣不可靠。 事情必須改變！

Andrej: All right, look. You are my most loyal customer, and I didn't want to charge you, but my shareholders forced me.

安德烈：好的，看。 您是我最忠實(shí)的客戶，我不想向您收費(fèi)，但我的股東強(qiáng)迫我。

Let me re-program my system and make it completely transparent and decentralized. After all, if everyone were able to interact with the bar without going through me, it would significantly improve the bar's efficiency and balance the level of trust!

讓我重新編程我的系統(tǒng)，使其完全透明和分散。 畢竟，如果每個(gè)人都可以在不經(jīng)過我的情況下與律師協(xié)會(huì)互動(dòng)，那將大大提高律師協(xié)會(huì)的效率并平衡信任度！

• Ordering drinks would take seconds instead of minutes
  訂購飲料將花費(fèi)幾秒鐘而不是幾分鐘
• The customers who forgot their wallets at home could borrow or lend tokens to each other
  在家忘記錢包的客戶可以互相借用或借出代幣
• I wouldn't have to worry about losing the clients data (again) as everyone would have a copy of it
  我不必?fù)?dān)心再次丟失客戶數(shù)據(jù)，因?yàn)槊總€(gè)人都會(huì)有一個(gè)副本

• The database would be immutable, so once everyone would agree on a specific state, no one else can change it or maliciously modify the history. Immutability would help with yearly tax audits as well!

  數(shù)據(jù)庫將是不可變的，因此一旦每個(gè)人都同意一個(gè)特定狀態(tài)，其他任何人都無法更改它或惡意修改歷史記錄。 不變性也將有助于年度稅收審核！

• If shareholders wanted to introduce new fees or raise the current ones, everyone involved in the blockchain system would notice and have to agree with it. The users and business owners would even have to engage in some decentralized governance system together, based on voting, probably. In case of a disagreement, the users walk away with all their data!
  如果股東想引入新的費(fèi)用或提高當(dāng)前費(fèi)用，那么參與區(qū)塊鏈系統(tǒng)的每個(gè)人都會(huì)注意到并必須同意。 用戶和企業(yè)所有者甚至可能不得不基于投票一起參與某種分散的治理系統(tǒng)。 如有分歧，用戶將放棄所有數(shù)據(jù)！

BabaYaga: Well, it certainly sounds good, but is this even possible?

BabaYaga：嗯，聽起來確實(shí)不錯(cuò)，但這是否可能？

Andrej: Yes, I think so. With a bit of hashing, linked lists, immutable data structure, distributed replication, and asymmetric cryptography!

安德烈：是的，我是這樣認(rèn)為的。 帶有一些散列，鏈表，不變的數(shù)據(jù)結(jié)構(gòu)，分布式復(fù)制和非對(duì)稱密碼！

BabaYaga: I have no idea what you have just said but go and do your geeky thing, Andrej!

BabaYaga：我不知道你剛才說了什么，但是去做你的怪異事，Andrej！

💡有趣的事實(shí) (💡Fun Facts)

Bitcoin and Ethereum miners also receive rewards every ~15 minutes for running the blockchain servers (nodes) and validating transactions.比特幣和以太坊礦工還通過運(yùn)行區(qū)塊鏈服務(wù)器(節(jié)點(diǎn))和驗(yàn)證交易每15分鐘獲得獎(jiǎng)勵(lì)。 Every 15 minutes, one Bitcoin miner receives 12.5 BTC ($100k at the moment of writing this page) to cover his servers cost + make some profit.每15分鐘，一名比特幣礦工獲得12.5 BTC(在撰寫此頁面時(shí)為10萬美元)以支付他的服務(wù)器成本+獲利。 The Bitcoin network consumes as much electricity as the entire country of Austria. It accounts for 0.29% of the world's annual electricity consumption.比特幣網(wǎng)絡(luò)消耗的電量與整個(gè)奧地利國家一樣多。 它占世界年度用電量的0.29％。

Annually it consumes 76.84 TWh, producing 36.50 Mt CO2 carbon footprint (New Zealand). Source.

每年消耗76.84 TWh，產(chǎn)生36.50 Mt的二氧化碳足跡(新西蘭)。 資源。

Why? You will learn more later (in Chapter 11) where you will program a Bitcoin mining algorithm from scratch!為什么？ 您將在后面的第11章中了解更多信息，從頭開始編寫比特幣挖掘算法！ PS: Our algorithm will consume a bit less electricity :)PS：我們的算法將消耗更少的電量:)

📌總結(jié) (📌 Summary)

Closed software with centralized access to private data allows for just a handful of people to have a lot of power. Users don’t have a choice, and shareholders are in business to make money.

具有集中訪問私有數(shù)據(jù)功能的封閉式軟件僅使少數(shù)人擁有很大的權(quán)力。 用戶別無選擇，股東經(jīng)營業(yè)務(wù)是為了賺錢。

Blockchain developers aim to develop protocols where applications' entrepreneurs and users synergize in a transparent, auditable relationship. Specifications of the blockchain system should be well-defined from the beginning and only change if its users support it.

區(qū)塊鏈開發(fā)人員旨在開發(fā)協(xié)議，使應(yīng)用程序的企業(yè)家和用戶以透明，可審核的關(guān)系協(xié)同工作。 區(qū)塊鏈系統(tǒng)的規(guī)范應(yīng)從一開始就進(jìn)行明確定義，并且只有在其用戶支持的情況下才可以更改。

Blockchain is a database. The token supply, initial user balances, and global blockchain settings are defined in a Genesis file. The Genesis balances indicate what was the original blockchain state and are never updated afterwards.

區(qū)塊鏈?zhǔn)且粋€(gè)數(shù)據(jù)庫。 代幣供應(yīng)，初始用戶余額和全局區(qū)塊鏈設(shè)置在Genesis文件中定義。 創(chuàng)世余額表明最初的區(qū)塊鏈狀態(tài)是什么，以后再也不會(huì)更新。

The database state changes are called Transactions (TX). Transactions are old fashion Events representing actions within the system.

數(shù)據(jù)庫狀態(tài)更改稱為事務(wù)(TX)。 事務(wù)是老式的事件，代表系統(tǒng)內(nèi)的動(dòng)作。

?學(xué)習(xí)代碼 (? Study Code)

Commit: 642045

提交： 642045

06 | 不可改變的哈希 (06 | L'Hash de Immutable)

? git checkout c6_immutable_hash

git checkout c6_immutable_hash

The technical difficulty starts with this section! The concepts will only get more challenging but at the same time, very exciting. Buckle up :)

技術(shù)難度從本節(jié)開始！ 這些概念只會(huì)變得更具挑戰(zhàn)性，但同時(shí)也非常令人興奮。 系好安全帶 ：)

如何編程一個(gè)不變的數(shù)據(jù)庫？ (How to Program an Immutable Database?)

Friday, March 29.

3月29日，星期五。

If Andrej wants to figure out how to program an immutable DB, he has to realize why other database systems are mutable by design.

如果Andrej想弄清楚如何編寫一個(gè)不變的DB，他必須意識(shí)到為什么其他數(shù)據(jù)庫系統(tǒng)在設(shè)計(jì)上是可變的。

He decides to analyze an all-mighty MySQL DB Table:

他決定分析一個(gè)全能MySQL數(shù)據(jù)庫表：

| id | name | balance | | -- | -------- | ------- | | 1 | Andrej | 998951 | | 2 | BabaYaga | 949 | | 3 | Caesar | 1000 |

In MySQL DB, anyone with access and a good enough reason can perform a table update such as:

在MySQL DB中，具有訪問權(quán)限并有充分理由的任何人都可以執(zhí)行表更新，例如：

UPDATE user_balance SET balance = balance + 100 WHERE id > 1

Updating values across different rows is possible because the table rows are independent, mutable, and the latest state is not apparent.

跨表更新值是可能的，因?yàn)楸硇惺仟?dú)立的，可變的，并且最新狀態(tài)不明顯。

What’s the latest DB change? Last column changed? Last row inserted? If so, how can Andrej know what row was deleted recently? If the rows and table state were tightly coupled, dependent, a.k.a, updating row 1 would generate a completely new, different table, Andrej would achieve his immutability.

最新的數(shù)據(jù)庫更改是什么？ 最后一欄改變了？ 最后插入行？ 如果是這樣，Andrej如何知道最近刪除了哪一行？ 如果行和表的狀態(tài)緊密耦合，相互依賴(也稱為更新)，則更新第1行將生成一個(gè)全新的不同表，Andrej將實(shí)現(xiàn)其不變性。

How can you tell if any byte in a database has changed?您如何判斷數(shù)據(jù)庫中的任何字節(jié)是否已更改？

通過哈希函數(shù)實(shí)現(xiàn)不變性 (Immutability via Hash Functions)

Hashing is process of taking a string input of arbitrary length and producing a hash string of fixed length. Any change in input, will result in a new, different hash.

散列是獲取任意長度的字符串輸入并生成固定長度的散列字符串的過程。 輸入的任何更改都將導(dǎo)致新的不同哈希值。

package mainimport ("crypto/sha256""fmt" )func main() {balancesHash := sha256.Sum256([]byte("| 1 | Andrej | 99895 |"))fmt.Printf("%x\n", balancesHash)// Output: 6a04bd8e2...f70a3902374f21e089ae7cc3b200751// Change balance from 99895 -> 99896balancesHashDiff := sha256.Sum256([]byte("| 1 | Andrej | 99896 |"))fmt.Printf("%x\n", balancesHashDiff)// Output: d04279207...ec6d280f6c7b3e2285758030292d5e1 }

Try it: https://play.golang.org/p/FTPUa7IhOCE

嘗試一下： https : //play.golang.org/p/FTPUa7IhOCE

Andrej also requires some level of security for his database, so he decides for a Cryptographic Hash Function with the following properties:

Andrej還要求其數(shù)據(jù)庫具有某種程度的安全性，因此他決定使用具有以下屬性的加密散列函數(shù) ：

• it is deterministic - the same message always results in the same hash

  它是確定性的 -相同的消息始終導(dǎo)致相同的哈希

• it is quick to compute the hash value for any given message
  快速計(jì)算任何給定消息的哈希值
• it is infeasible to generate a message from its hash value except by trying all possible messages
  根據(jù)其哈希值生成消息是不可行的，除非嘗試所有可能的消息
• a small change to a message should change the hash value so extensively that the new hash value appears uncorrelated with the old hash value
  對(duì)消息進(jìn)行很小的更改就應(yīng)該廣泛更改哈希值，以使新的哈希值看起來與舊的哈希值不相關(guān)

• it is infeasible to find two different messages with the same hash value

  找到具有相同哈希值的兩個(gè)不同消息是不可行的

實(shí)施數(shù)據(jù)庫內(nèi)容哈希 (Implementing the DB Content Hashing)

Saturday Evening, March 30.

3月30日，星期六晚上。

Andrej modifies the Persist() function to return a new content hash, Snapshot, every time a new transaction is persisted.

每當(dāng)新事務(wù)持久化時(shí)，Andrej都會(huì)修改Persist()函數(shù)以返回新的內(nèi)容哈希Snapshot 。

type Snapshot [32]byte

The Snapshot is produced by this new sha256 secure hashing function:

Snapshot由此新的sha256 secure hashing函數(shù)生成：

func (s *State) doSnapshot() error {// Re-read the whole file from the first byte_, err := s.dbFile.Seek(0, 0)if err != nil {return err}txsData, err := ioutil.ReadAll(s.dbFile)if err != nil {return err}s.snapshot = sha256.Sum256(txsData)return nil }

The doSnapshot() is called by the modified Persist() function. When a new transaction is written into the tx.db file, the Persist() hashes the entire file content and returns its 32 bytes "fingerprint" hash.

doSnapshot()由修改后的Persist()函數(shù)調(diào)用。 當(dāng)將新事務(wù)寫入tx.db文件時(shí)， Persist()將對(duì)整個(gè)文件內(nèi)容進(jìn)行哈希處理并返回其32個(gè)字節(jié)的“指紋”哈希值。

From this moment, everyone can 100% confidently and securely refer to any particular database state (set of data) with a specific snapshot hash.

從這一刻起，每個(gè)人都可以100％自信和安全地使用特定的快照哈希引用任何特定的數(shù)據(jù)庫狀態(tài)(數(shù)據(jù)集)。

?實(shí)踐時(shí)間 (?Practice time)

1/4 Run the tbb balances list cmd and check the balances are matching.

1/4運(yùn)行tbb balances list cmd并檢查余額是否匹配。

? tbb balances list

tbb balances list

Account balances at 7d4a360f465d...| id | name | balance | | -- | -------- | ------- | | 1 | Andrej | 999251 | | 2 | BabaYaga | 949 | | 3 | Caesar | 1000 |

2/4 Remove the last 2 rows from ./database/tx.db and check the balances again.

2/4從./database/tx.db刪除最后2行， ./database/tx.db再次檢查余額。

? tbb balances list

tbb balances list

Account balances at 841770dcd3...| id | name | balance | | -- | -------- | ------- | | 1 | Andrej | 999051 | | 2 | BabaYaga | 949 | | 3 | Caesar | 1000 |

3/4 Reward Andrej for the last 2 days (from 28th to 30th of March):

最后2天(3月28日至30日)的3/4獎(jiǎng)勵(lì)安德烈：

Reward Transaction 1:

獎(jiǎng)勵(lì)交易1：

? tbb tx add --from=andrej --to=andrej --value=100 --data=reward

tbb tx add --from=andrej --to=andrej --value=100 --data=reward

Persisting new TX to disk:{"from":"andrej","to":"andrej","value":100,"data":"reward"}New DB Snapshot: ff2470c7043f5a34169b5dd38921ba6825b03b3facb83e426 TX successfully persisted to the ledger.

Reward Transaction 2:

獎(jiǎng)勵(lì)交易2：

? tbb tx add --from=andrej --to=andrej --value=100 --data=reward

tbb tx add --from=andrej --to=andrej --value=100 --data=reward

Persisting new TX to disk:{"from":"andrej","to":"andrej","value":100,"data":"reward"}New DB Snapshot: 7d4a360f468b837b662816bcdc52c1869f99327d53ab4a9ca TX successfully persisted to the ledger.

4/4 Run the tbb balances list cmd and ensure the balances and the snapshot hash is the same as at the beginning.

4/4運(yùn)行tbb balances list cmd，并確保余額和快照哈希與開頭相同。

? tbb balances list

tbb balances list

Account balances at 7d4a360f465d...| id | name | balance | | -- | -------- | ------- | | 1 | Andrej | 999251 | | 2 | BabaYaga | 949 | | 3 | Caesar | 1000 |

Done!

做完了！

Because the cryptographic hash function sha256 produces the same output (given the same inputs (current tx.db and 2x tbb tx add)), if you follow the exact steps on your own computer, you will generate the exact same database state and hashes!

因?yàn)榧用苌⒘泻瘮?shù)sha256產(chǎn)生相同的輸出(給定相同的輸入(當(dāng)前tx.db和2x tbb tx add ))，所以如果您在自己的計(jì)算機(jī)上執(zhí)行確切的步驟，則將生成完全相同的數(shù)據(jù)庫狀態(tài)和哈希！

📌總結(jié) (📌 Summary)

Closed software with centralized access to private data puts only a few people to the position of power. Users don’t have a choice, and shareholders are in business to make money.

具有集中式訪問私有數(shù)據(jù)功能的封閉式軟件僅使少數(shù)人享有權(quán)力。 用戶別無選擇，股東經(jīng)營業(yè)務(wù)是為了賺錢。

Blockchain developers aim to develop protocols where applications' entrepreneurs and users synergize in a transparent, auditable relation. Specifications of the blockchain system should be well defined from the beginning and only change if its users support it.

區(qū)塊鏈開發(fā)人員旨在開發(fā)協(xié)議，使應(yīng)用程序的企業(yè)家和用戶以透明，可審核的關(guān)系協(xié)同工作。 區(qū)塊鏈系統(tǒng)的規(guī)范應(yīng)該從一開始就很好地定義，并且只有在其用戶支持的情況下才可以更改。

Blockchain is an immutable database. The token supply, initial user balances, and global blockchain settings you define in a Genesis file. The Genesis balances indicate what was the original blockchain state and are never updated afterwards.

區(qū)塊鏈?zhǔn)且粋€(gè)不變的數(shù)據(jù)庫。 您在Genesis文件中定義的令牌供應(yīng)，初始用戶余額和全局區(qū)塊鏈設(shè)置。 創(chuàng)世余額表明最初的區(qū)塊鏈狀態(tài)是什么，以后再也不會(huì)更新。

The database state changes are called Transactions (TX). Transactions are old fashion Events representing actions within the system.

數(shù)據(jù)庫狀態(tài)更改稱為事務(wù)(TX)。 事務(wù)是老式的事件，代表系統(tǒng)內(nèi)的動(dòng)作。

The database content is hashed by a secure cryptographic hash function. The blockchain participants use the resulted hash to reference a specific database state.

數(shù)據(jù)庫內(nèi)容由安全的密碼哈希函數(shù)哈希。 區(qū)塊鏈參與者使用所得的哈希值來引用特定的數(shù)據(jù)庫狀態(tài)。

?學(xué)習(xí)代碼 (? Study Code)

Commit: b99e51

提交： b99e51

?下一步 (?Next steps)

You finished the first few chapters! Congratulations!

您完成了前幾章！ 恭喜你！

█????????? 10%

█??????????10％

But this was just a quick warm-up. Blockchain is a very challenging and extensive technology, and you would need an entire book explaining how to build the full system and all of its components from scratch - so I wrote one.

但這只是一個(gè)快速的熱身。 區(qū)塊鏈?zhǔn)且豁?xiàng)非常具有挑戰(zhàn)性和廣泛性的技術(shù)，您需要整本書來解釋如何從頭開始構(gòu)建完整的系統(tǒng)及其所有組件-所以我寫了一本。

You can continue reading in the next free chapter in my newsletter version of "The Blockchain Way of Programming" eBook.

您可以繼續(xù)在我的通訊版本“ The Blockchain Way of Programming”電子書的下一個(gè)免費(fèi)章節(jié)中繼續(xù)閱讀。

07 | The Blockchain Programming Model

07 | 區(qū)塊鏈編程模型

• Improving Performance of an Immutable DB
  提高不可變數(shù)據(jù)庫的性能
• Batch + Hash + Linked List ? Blocks
  批處理+哈希+鏈接列表?塊
• Migrating from TX.db to BLOCKS.db
  從TX.db遷移到BLOCKS.db

Learning: You redesign and refactor your MVP database into a blockchain architecture.

學(xué)習(xí)：您將MVP數(shù)據(jù)庫重新設(shè)計(jì)和重構(gòu)為區(qū)塊鏈架構(gòu)。

繼續(xù)本教程： https：//web3.coach#book (Continue in the tutorial: https://web3.coach#book)

Thanks for reading!

謝謝閱讀！

翻譯自: https://www.freecodecamp.org/news/build-a-blockchain-in-golang-from-scratch/

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