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Translating by qhwdw
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Blockchain evolution: A quick guide and why open source is at the heart of it
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======
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It isn't uncommon, when working on a new version of an open source project, to suffix it with "-ng", for "next generation." Fortunately, in their rapid evolution blockchains have so far avoided this naming pitfall. But in this evolutionary open source ecosystem, changes have been abundant, and good ideas have been picked up, remixed, and evolved between many different projects in a typical open source fashion.
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In this article, I will look at the different generations of blockchains and what ideas have emerged to address the problems the ecosystem has encountered. Of course, any attempt at classifying an ecosystem will have limits—and objectors—but it should provide a rough guide to the jungle of blockchain projects.
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### The beginning: Bitcoin
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The first generation of blockchains stems from the [Bitcoin][1] blockchain, the ledger underpinning the decentralized, peer-to-peer cryptocurrency that has gone from [Slashdot][2] miscellanea to a mainstream topic.
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This blockchain is a distributed ledger that keeps track of all users' transactions to prevent them from double-spending their coins (a task historically entrusted to third parties: banks). To prevent attackers from gaming the system, the ledger is replicated to every computer participating in the Bitcoin network and can be updated by only one computer in the network at a time. To decide which computer earns the right to update the ledger, the system organizes every 10 minutes a race between the computers, which costs them (a lot of) energy to enter. The winner wins the right to commit the last 10 minutes of transactions to the ledger (the "block" in blockchain) and some Bitcoin as a reward for their efforts. This setup is called a _proof of work_ consensus mechanism.
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The goal of using a blockchain is to raise the level of trust participants have in the network.
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This is where it gets interesting. Bitcoin was released as an [open source project][3] in January 2009. In 2010, realizing that quite a few of these elements can be tweaked, the community that had aggregated around Bitcoin, often on the [bitcointalk forums][4], started experimenting with them.
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First, seeing that the Bitcoin blockchain is a form of a distributed database, the [Namecoin][5] project emerged, suggesting to store arbitrary data in its transaction database. If the blockchain can record the transfer of money, it could also record the transfer of other assets, such as domain names. This is exactly Namecoin's main use case, which went live in April 2011, two years after Bitcoin's introduction.
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Where Namecoin tweaked the content of the blockchain, [Litecoin][6] tweaked two technical aspects: reducing the time between two blocks from 10 to 2.5 minutes and changing how the race is run (replacing the SHA-256 secure hashing algorithm with [scrypt][7]). This was possible because Bitcoin was released as open source software and Litecoin is essentially identical to Bitcoin in all other places. Litecoin was the first fork to modify the consensus mechanism, paving the way for many more.
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Along the way, many more variations of the Bitcoin codebase have appeared. Some started as proposed extensions to Bitcoin, such as the [Zerocash][8] protocol, which aimed to provide transaction anonymity and fungibility but was eventually spun off into its own currency, [Zcash][9].
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While Zcash has brought its own innovations, using recent cryptographic advances known as zero-knowledge proofs, it maintains compatibility with the vast majority of the Bitcoin code base, meaning it too can benefit from upstream Bitcoin innovations.
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Another project, [CryptoNote][10], didn't use the same code base but sprouted from the same community, building on (and against) Bitcoin and again, on older ideas. Published in December 2012, it led to the creation of several cryptocurrencies, of which [Monero][11] (2014) is the best-known. Monero takes a different approach to Zcash but aims to solve the same issues: privacy and fungibility.
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As is often the case in the open source world, there is more than one tool for the job.
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### The next generations: "Blockchain-ng"
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So far, however, all these variations have only really been about refining cryptocurrencies or extending them to support another type of transaction. This brings us to the second generation of blockchains.
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Once the community started modifying what a blockchain could be used for and tweaking technical aspects, it didn't take long for some people to expand and rethink them further. A longtime follower of Bitcoin, [Vitalik Buterin][12] suggested in late 2013 that a blockchain's transactions could represent the change of states of a state machine, conceiving the blockchain as a distributed computer capable of running applications ("smart contracts"). The project, [Ethereum][13], went live in July 2015. It has seen fair success in running distributed apps, and the popularity of some of its better-known distributed apps ([CryptoKitties][14]) have even caused the Ethereum blockchain to slow down.
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This demonstrates one of the big limitations of current blockchains: speed and capacity. (Speed is often measured in transactions per second, or TPS.) Several approaches have been suggested to solve this, from sharding to sidechains and so-called "second-layer" solutions. The need for more innovation here is strong.
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With the words "smart contract" in the air and a proved—if still slow—technology to run them, another idea came to fruition: permissioned blockchains. So far, all the blockchain networks we've described have had two unsaid characteristics: They are public (anyone can see them function), and they are without permission (anyone can join them). These two aspects are both desirable and necessary to run a distributed, non-third-party-based currency.
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As blockchains were being considered more and more separately from cryptocurrencies, it started to make sense to consider them in some private, permissioned settings. A consortium-type group of actors that have business relationships but don't necessarily trust each other fully can benefit from these types of blockchains—for example, actors along a logistics chain, financial or insurance institutions that regularly do bilateral settlements or use a clearinghouse, idem for healthcare institutions.
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Once you change the setting from "anyone can join" to "invitation-only," further changes and tweaks to the blockchain building blocks become possible, yielding interesting results for some.
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For a start, proof of work, designed to protect the network from malicious and spammy actors, can be replaced by something simpler and less resource-hungry, such as a [Raft][15]-based consensus protocol. A tradeoff appears between a high level of security or faster speed, embodied by the option of simpler consensus algorithms. This is highly desirable to many groups, as they can trade some cryptography-based assurance for assurance based on other means—legal relationships, for instance—and avoid the energy-hungry arms race that proof of work often leads to. This is another area where innovation is ongoing, with [Proof of Stake][16] a notable contender for the public network consensus mechanism of choice. It would likely also find its way to permissioned networks too.
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Several projects make it simple to create permissioned blockchains, including [Quorum][17] (a fork of Ethereum) and [Hyperledger][18]'s [Fabric][19] and [Sawtooth][20], two open source projects based on new code.
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Permissioned blockchains can avoid certain complexities that public, non-permissioned ones can't, but they still have their own set of issues. Proper management of participants is one: Who can join? How do they identify? How can they be removed from the network? Does one entity on the network manage a central public key infrastructure (PKI)?
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The open nature of blockchains is seen as a form of governance.
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### Open nature of blockchains
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In all of the cases so far, one thing is clear: The goal of using a blockchain is to raise the level of trust participants have in the network and the data it produces—ideally, enough to be able to use it as is, without further work.
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Reaching this level of trust is possible only if the software that powers the network is free and open source. Even a correctly distributed proprietary blockchain is essentially a collection of independent agents running the same third party's code. By nature, it's necessary—but not sufficient—for a blockchain's source code to be open source. This has both been a minimum guarantee and the source of further innovation as the ecosystem keeps growing.
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Finally, it is worth mentioning that while the open nature of blockchains has been a source of innovation and variation, it has also been seen as a form of governance: governance by code, where users are expected to run whichever specific version of the code contains a function or approach they think the whole network should embrace. In this respect, one can say the open nature of some blockchains has also become a cop-out regarding governance. But this is being addressed.
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### Third and fourth generations: governance
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Next, I will look at what I am currently considering the third and fourth generations of blockchains: blockchains with built-in governance tools and projects to solve the tricky question of interconnecting the multitude of different blockchain projects to let them exchange information and value with each other.
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--------------------------------------------------------------------------------
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via: https://opensource.com/article/18/6/blockchain-guide-next-generation
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作者：[Axel Simon][a]
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选题：[lujun9972](https://github.com/lujun9972)
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]:https://opensource.com/users/axel
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[1]:https://bitcoin.org
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[2]:https://slashdot.org/
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[3]:https://github.com/bitcoin/bitcoin
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[4]:https://bitcointalk.org/
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[5]:https://www.namecoin.org/
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[6]:https://litecoin.org/
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[7]:https://en.wikipedia.org/wiki/Scrypt
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[8]:http://zerocash-project.org/index
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[9]:https://z.cash
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[10]:https://cryptonote.org/
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[11]:https://en.wikipedia.org/wiki/Monero_(cryptocurrency)
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[12]:https://en.wikipedia.org/wiki/Vitalik_Buterin
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[13]:https://ethereum.org
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[14]:http://cryptokitties.co/
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[15]:https://en.wikipedia.org/wiki/Raft_(computer_science)
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[16]:https://www.investopedia.com/terms/p/proof-stake-pos.asp
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[17]:https://www.jpmorgan.com/global/Quorum
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[18]:https://hyperledger.org/
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[19]:https://www.hyperledger.org/projects/fabric
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[20]:https://www.hyperledger.org/projects/sawtooth
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区块链进化史：一个快速导览和为什么开源是其核心所在
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======
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当在开源项目的一个新版本上工作时，用后缀 "-ng" 表示 ”下一代“的情况并不鲜见。幸运的是，到目前为止，快速演进的区块链成功地避开了这个命名陷阱。但是在这个开源生态系统的演进过程中，改变是不断发生的，而好的创意被采用、融入、并以典型的开源方式进化到许多不同的项目中。
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在本文中，我将审视不同代次的区块链，并且看一看他们在处理生态系统遇到的问题时采用了什么创意。当然，任何对生态系统进行分类的尝试都有其局限性的 —— 和反对者的 —— 但是这也将为混乱的区块链项目提供了一个粗略的指南。
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### 始作蛹者：比特币（Bitcoin）
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第一代的区块链起源于 [比特币][1] 区块链，以去中心化为基础的总帐，从 [Slashdot][2] 杂集变成主流话题的点对点加密货币。
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这个区块链是一个分布式总帐，它对所有用户的事务保持跟踪，以避免它们的货币重复支付（在历史上，这个任务是委托给第三方—— 银行 ——来做的）。为防范攻击者在系统上捣乱，总帐被复制到每个参与到比特币网络的计算机上，并且每次只允许一台计算机去更新总帐。为决定哪台计算机能够获得更新总帐的权力，系统安排在比特币网络上的计算机之间每 10 分钟进行一场竞赛，这将消耗它们的（许多）能源。赢家将获得将前 10 分钟发生的事务写入到总帐（区块链中的“区块”）的权力，并且为赢家写入区块链的工作给予一些比特币奖励。这些设置被称为一个 _工作量证明_ 共识机制。
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使用区块链的目标是提升网络中参与者的信任水平。
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这就是区块链最有趣的地方。比特币是发布于 2009 年 1 月的一个 [开源项目][3]。在 2010 年，由于意识到这些元素中的许多是可以调整的，围绕比特币聚集起了一个社区 —— [bitcointalk forums][4]，来开始各种实验。
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起初，看到的比特币区块链是一个分布式数据库的形式， [Namecoin][5] 项目出现后，建议去保存任意数据到它的事务数据库中。如果区块链能够记录金钱的转移，那么它也应该能够记录其它资产的转移，比如域名。这确实是 Namecoin 的主要使用案例，它上线于 2011 年 4 月 —— 也就是比特币出现两年后。
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Namecoin 调整的地方是区块链的内容，[莱特币（Litecoin）][6] 调整了两个技术部分：一是将两个区块的时间间隔从 10 分钟减少到 2.5 分钟，二是改变了竞赛方式（用 [scrypt][7] 来替换 SHA-256 安全哈希算法）。这是能够做到的，因为比特币是以开源软件的方式来发布的，而莱特币本质上与比特币在其它部分是完全相同的。莱特币是修改了比特币共识机制的第一个分叉，这也为其它的更多“币”铺平了道路。
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沿着这条道路，基于比特币代码库的各种变种越来越多。其中一些扩展了比特币的用途，比如 [Zerocash][8] 协议，它专注于提供交易的匿名性和可替换性，但它最终分拆为它自己的货币 —— [Zcash][9]。
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虽然 Zcash 带来了它自己的创新，使用了最近被称为“零知识证明”的加密技术，但它维持着与大多数主要的比特币代码库的兼容性，这意味着它能够从上游的比特币创新中获益。
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另外的项目 —— [CryptoNote][10]，它萌芽于相同的社区，但是并没有使用相同的代码，它以比特币为背景来构建的，但又与之不同。它发行于 2012 年 12 月，由于它的出现，导致了几种加密货币的诞生，最著名的 [Monero][11] (2014) 就是其中之一。Monero 与 Zcash 使用了不同的方法，但解决了相同的问题：隐私性和可替换性。
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就像在开源世界中经常出现的案例一样，做同样的工作有不止一个的工具可用。
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### 下一代："Blockchain-ng"
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但是，到目前为止，所有的这些变体只是改进加密货币或者扩展它们去支持其它类型的事务。因此，这就引出了第二代区块链。
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一旦社区开始去修改区块链的用法和调整技术部分时，对于一些想去扩展和重新思考它们未来的人来说，这种调整花费不了多长时间的。比特币的长期追随者 —— [Vitalik Buterin][12] 在 2013 年底建议，区域链的事务应该能够表示一个状态机的状态变化，将区域链识为能够运行应用程序（“智能合约”）的分布式计算机。这个项目 —— [以太坊（Ethereum）][13]，上线于 2015 年 4 月。它在运行分布式应用程序方面取得了巨大的成功，它的一些非常流行的分布式应用程序（[CryptoKitties][14]）甚至导致以太坊区块链变得很慢。
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这证明了目前的区块链存在一个很大的局限性：速度和容量。（速度通常用每秒事务数来测量，简称 TPS）有几个提议都建议去解决这个速度问题，从分片到侧链，以及一个被称为“第二层（second-layer)”的解决方案。这里需要更多的创新。
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随着“智能合约”这个词开始流行起来，并且一件被证明的事情是 —— 如果仍然用很慢的技术去运行它们，那么就需要另外的即将要实现的创意：许可区块链（Permissioned blockchains）。到目前为止，所有的区块链网络上，我们有两个没有明说的特征：一是它们是公开的（任何人都可以看到它们的功能），二是它们没有许可（任何人都可以加入它们）。这两个部分是运行一个分布式的、非基于第三方货币应该具有的和必需具有的条件。
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随着区块链被认为出现与加密货币越来越明显的分离趋势，开始去考虑一些隐私、许可设置是很有意义的。一个有业务关系但相互之间完全不信任的财团类型的参与者，能够从这些区块链类型中获益 —— 比如，物流链上的参与者，定期进行双边结算或者使用一个清算中心的金融、保险、或医疗保健机构。
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一旦你将设置从“任何人都可以加入”变为“仅邀请者方可加入”，进一步对区块链构建区块的方式进行改变和调整将变得可能，那么对一些人来说，结果将变得非常有趣。
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首先，为了保护网络不受恶意或者垃圾参与者的影响，工作量证明被替换为更简单的和更少资源消耗的一些东西，比如，基于 [Raft][15] 的共识协议。在更高级别的安全性和更快的速度之间进行权衡，采用更简单的共识算法。对于更多群体来说这样更理想，因为他们可以用基于加密技术的担保来取代其它的基于法律关系的担保，例如为避免由于竞争而产生的大量能源消耗，而工作量证明就是这种情况。另外一个创新的地方是，使用 [股权证明（Proof of Stake）][16]，它是公共网络共识机制的一个重量级的竞争者。它将可能像许可网络一样找到它自己的实现方式。
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有几个项目可以让创建许可区块链变得更简单，包括 [Quorum][17] （以太坊的一个分叉）和 [Hyperledger][18] 的 [Fabric][19] 和 [Sawtooth][20]，基于新代码的两个开源项目。
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许可区块链可以避免公共的、非许可方式的区块链中某些错综复杂的问题，但是它自己也存在一些问题。正确地管理参与者是其中的一个问题：谁可以加入？如何辨别他们？如何将他们从网络上移除？网络上的一个实体是否去管理一个中央公共密钥基础设施（PKI）?
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区块链的开放本质被识为一种治理形式。
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### 区块链的开放本质
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到目前为止的所有案例中，有一件事情是很明确的：使用一个区块链的目标是去提升网络中的参与者和它产生的数据的信任水平，理想情况下，不需要做进一步的工作即可足以使用它。
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只有为这个网络提供动力的软件是自由和开源的，才能达到这种信任水平。即便是一个正确的、专用的、分布式区块链，它的本质仍然是运行着相同的第三方代码的私有代理的集合。从本质上来说，区块链的源代码必须是开源的，但仅是开源还不够，随着生态系统持续成长，这既是最低限度的担保也是进一步创新的源头。
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最后，值得一提的是，虽然区块链的开放本质被认为是创新和变化的源头，它也被认为是一种治理形式：代码治理，用户期望运行的任何一个特定版本，都应该包含他们认为的整个网络应该包含的功能和方法。在这方面，需要说明的一点是，一些区块链的开放本质正在“变味”。但是这一问题正在解决。
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### 第三和第四代：治理
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接下来，我正在考虑第三和第四代区块链：区块链将内置治理工具，以及项目将去解决棘手的大量不同区块链之间互连互通的问题，以便于它们之间可以交换信息和价值。
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--------------------------------------------------------------------------------
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via: https://opensource.com/article/18/6/blockchain-guide-next-generation
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作者：[Axel Simon][a]
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||||
选题：[lujun9972](https://github.com/lujun9972)
|
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译者：[qhwdw](https://github.com/qhwdw)
|
||||
校对：[校对者ID](https://github.com/校对者ID)
|
||||
|
||||
本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
|
||||
|
||||
[a]:https://opensource.com/users/axel
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||||
[1]:https://bitcoin.org
|
||||
[2]:https://slashdot.org/
|
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[3]:https://github.com/bitcoin/bitcoin
|
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[4]:https://bitcointalk.org/
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||||
[5]:https://www.namecoin.org/
|
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[6]:https://litecoin.org/
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[7]:https://en.wikipedia.org/wiki/Scrypt
|
||||
[8]:http://zerocash-project.org/index
|
||||
[9]:https://z.cash
|
||||
[10]:https://cryptonote.org/
|
||||
[11]:https://en.wikipedia.org/wiki/Monero_(cryptocurrency)
|
||||
[12]:https://en.wikipedia.org/wiki/Vitalik_Buterin
|
||||
[13]:https://ethereum.org
|
||||
[14]:http://cryptokitties.co/
|
||||
[15]:https://en.wikipedia.org/wiki/Raft_(computer_science)
|
||||
[16]:https://www.investopedia.com/terms/p/proof-stake-pos.asp
|
||||
[17]:https://www.jpmorgan.com/global/Quorum
|
||||
[18]:https://hyperledger.org/
|
||||
[19]:https://www.hyperledger.org/projects/fabric
|
||||
[20]:https://www.hyperledger.org/projects/sawtooth
|
||||
Loading…
Reference in New Issue
Block a user