Ethereum ledger

1. Go full stack + blockchain course:
a total of 22 weeks, divided into five stages,
the first stage is 4 weeks, go language foundation and network concurrency, learning the introctory go language,
the second stage is 4 weeks, go language practical web development, crawler development, cryptography, consensus algorithm, realizing lightweight public chain, learning the website and crawler that can develop golang, Achieve lightweight blockchain
stage 3, 4-week Ethereum source code analysis and smart contract DAPP development, master Ethereum core and smart contract development, as well as blockchain,
stage 4, 4-week super ledger, bitcoin EOS, source code analysis and smart contract practice, master super ledger development, cat bitcoin, bifurcated EOS after learning, As well as DAPP development of smart contract
phase 5, 6-week project practice, five enterprise level projects, and one year of blockchain project experience after learning
from the characteristics of the language itself, go is a very efficient language, which highly supports concurrency. Go language itself pays more attention to distributed system, and concurrency processing is relatively good, such as advertising and search, That kind of high concurrency server
go language advantages:
excellent performance, can be directly compiled into machine code, does not rely on other libraries, go is extremely fast. Its performance is similar to Java or C + +
concurrency is supported at the language level, which is the biggest feature of go. It is born to support concurrency, and go is the concurrency supported in gene, which can make full use of multi-core and make it easy to use concurrency
the built-in runtime supports garbage collection, which is one of the features of dynamic language. Although GC is not perfect at present, it is enough to cope with most of the situations we can encounter, especially GC after go1.1
it's easy to learn. The authors of go language all have the gene of C, so go naturally has the gene of C. There are 25 go keywords, but the expressive ability is very strong. It almost supports most of the features you've seen in other languages: inheritance, overloading, object, etc
rich standard libraries, go has built a large number of libraries, especially the network library, which is also my favorite part< As like as two peas, br / > built-in powerful tools, Go language is built with many tools chain, the best should be gofmt tools, automatic formatting code, make team review become so simple, code format is exactly the same, it is very difficult to think differently.
cross platform compilation and fast compilation. Compared with the sluggish compilation speed of Java and C + +, the fast compilation time of go is a major efficiency advantage
disadvantages of go language:
package management: package management of go language is absolutely not perfect. By default, it has no way to make a specific version of the dependency library, nor can it create replicable builds. In contrast, python, node and Ruby all have better package management systems. However, with the right tools, the package management of go language can also perform well
lack of development framework: go language does not have a major framework, such as Ruby's rails framework, Python's Django framework or PHP's laravel. This is a heated discussion in the go language community, because many people think that we should not start with using frameworks. This is true in many cases, but if you just want to build a simple crud API, it's much easier to use Django / djrf, rails laravel, or Phoenix
exception handling: go language can help developers deal with compilation errors by simply returning errors (or call stack) through functions and expected calling codes. Although this method is effective, it is easy to lose the scope of the error, so it is difficult to provide meaningful error information to users. Error package can solve this problem by allowing us to add context and stack trace to return error
another problem is that we may forget to handle errors. Static analysis tools such as errcheck and megacheck can avoid these errors. Although these solutions are very effective, they may not be the right way.

2.

Bitcoin is not the only digital currency on the Internet. There are also ripple, stellar, litecoin, Ethereum and other digital currencies. Of course, the most popular is still bitcoin. But many times, some developers, entrepreneurs or enterprises will let us know that we need better digital currency. A programmer named Jed McCaleb, the father of electric donkeys, developed the reborn coin, which should be better than the bitcoin. Later, he launched the star coin, which is better than the reborn coin. What is more gratifying is that he is not fighting alone

now there is a trend that the instry hopes to develop a technology that enables all these online digital currencies to flow to each other, which means that you can transfer money freely in different online digital currency systems in the future. This technology is known as "interleaver protocol (ILP)", initiated by ripote. However, in recent months, that is, after the company released this idea, they also got the support of many famous companies in the instry, including Microsoft and the world wide web. Obviously, Ruibo currency company wants to set the technical standard of digital currency on the Internet. They want to develop a single global network, which can not only unify all digital currencies, but also unify all enterprises and indivials who use these digital currencies

"we want to be on a higher level and extract the differences between various digital currencies," said Stephen Thomas, chief technology officer of ripple. "We are trying to develop a global standard for payment."

with the launch of this agreement, we hope to enable more people to use online digital currency, expand the scope of use of online digital currency, and let us transfer funds more efficiently. This is actually the goal of many existing projects. For example, the original intention of the design of reborn currency and star currency is to allow users to transfer money to these two digital currency accounts in any currency, and to enable these two digital currencies to be converted into other currencies correspondingly. You can send bitcoin, and then the other party gets it. You can also send us dollars, and the other party will get dogecoin. However, for businesses and the developer community, there are restrictions on their use of these ledgers, so there are some problems because you can't transfer money from one payment network to another. Now, however, the interleaver agreement hopes to change that

to some extent, after ten years of efforts, they hope to develop a new network protocol, which is commonly known as "money Internet". If we go back to the early 1990s, we know that the famous Marc Andreessen founded the Netscape web browser. Now, the project hopes to play a similar role. They want to establish a standard way to send funds on the Internet. In fact, the original Hypertext Transfer Protocol (HTTP, which defined the basic standard of the network) contained code for payment. But this code has never been used. In recent years, many companies (such as coinbase, a bitcoin exchange, and stripe, a company that helps enterprises accept various online digital currencies) are at least trying to create a conventional standard for online digital currencies. In the future, we hope to be able to send and receive money online, just like sending short messages or e-mails. However, we still have a long way to go to this paradise, but at least now we are in the right direction

3. At present, there are many digital currency wallets, some of which have good personal experience

light wallets are good for imtoken, geekwallet, kcash, Cobo, etc.

Hardware wallets are good for ledger, trezor, etc., which involve large amount of digital currency or hold for a long time. Generally, hardware wallets are recommended

big body introces these personal good light wallets

1. Imtoken:

is a mobile light wallet app, which supports Eth and Ethereum erc2.0 standard tokens (such as EOS, DGD, SNT, qtum)

advantages: as Ethereum series light wallet, mtoken supports all the tokens of Ethereum erc2.0 standard, can control the miner's fee of each coin, can set the collection amount, and has convenient transaction record query, refreshing interface and easy operation, so it is suitable for ICO investors who need to receive a variety of erc2.0 standard tokens and trade infrequently

disadvantages: 1. The "discovery" mole of the wallet is not intuitive enough. 2. The tokens that can only be stored on the Ethereum platform, such as BTC and Neo, can't be stored. At the same time, the bifurcations of bitcoin can't be stored

2. Geek wallet

geek wallet is a simple and convenient light wallet, which supports the storage and management of mainstream digital currency assets such as bitcoin (BTC), lightcoin (LTC), Ethereum (ETH), EOS, usdt, etc. Using bip44 mnemonics, local private key, off-line signature and other security mechanisms, as well as mobile phone and computer al backup strategy, completely solve the loss of digital currency assets caused by hacker attacks, virus infection, mobile phone loss, forgetting mnemonics and other ways, and provide users with online Multi Chain digital assets one-stop management service. The platform also has tiaoshao market, which can carry out token trading of physical assets on the chain

advantages: it has high security factor, adopts local private key security mechanism, as well as mobile phone and computer al backup strategy, supports the current mainstream currency, and has a jump market on the platform, which can carry out token trading of physical assets on the chain

disadvantages: usdt transaction must use 0.0001 BTC as transaction handling fee, does not support some small currencies, page optimization is good, but the function is relatively few

3. Kcash

kcash is also a light wallet. At present, it supports BTC, ETH, LTC, etc, act and digital currency based on Ethereum and achain smart contract platform. Kcash has cross chain and cross contract technology, and the supported currencies are still increasing

advantages: as a Multi Chain Wallet, kcash supports multiple types of digital currencies and is very friendly to users who invest in multiple series of digital currencies. In addition, kcash also has the function of sending red packets, and in the future, it will launch currency transaction, bank card connection and other functions

deficiency: too many features lead to poor usability. In addition, there are some compatibility problems with Android versions. Some Android models will flash back when opening apps< Cobo

4. Cobo

Cobo is a professional digital asset management wallet, which can help you store your assets safely. The unique POS gain can help you increase the value of your assets. It supports more than 20 kinds of digital assets including eth, EOS and TRX, as well as more than 500 kinds of tokens

advantages: Cobo security is in the lead in the same level, using multiple security verification, hot and cold separation storage, HSM multi signature, Cobo provides you with stable income through intelligent voting, dpos vote pool, POS mining digital asset gain matrix

disadvantages: poor page optimization, complex functions, a little difficult to get started, and there is also a flash back problem of Android version

5. Ledger

Hardware wallet, which supports eth, BTC, zcash and other mainstream currencies, uses encryption chip technology to build security solutions for users, and is used to protect users' digital assets and block chain application security. This is a hardware bitcoin wallet specially designed for consumers. It provides enterprise level security hardware moles and hardware procts supporting the Internet of things

6, ledger

Hardware wallet, support eth, BTC, zcash and other mainstream currencies; Using encryption chip technology to build security solutions for users to protect users' digital assets and block chain application security. This is a hardware bitcoin wallet specially designed for consumers. It provides enterprise level security hardware moles and hardware procts supporting the Internet of things.

4. Blockchain is an important concept of bitcoin. It is essentially a decentralized database. At the same time, as the underlying technology of bitcoin, it is a series of data blocks generated by using cryptographic methods. Each data block contains a batch of information about bitcoin network transactions, Used to verify the validity of its information (anti-counterfeiting) and generate the next block.

5. Decentralized organization Dao launched smart contract for the world! Support 100% open source in github.io, true decentralization, 100% contract on the chain, intelligent constraints
start a 100% free on chain game! 100% fair
Plato world, in the name of trust, the coin circle opens the circle revolution< No server, no domain name, no app, no backstage, no customer service, no operator
all programs are built on Ethereum smart contracts and can only participate through formal Ethereum wallets such as imtoken
② funds are safe. All funds are in the contract (non personal address), and no indivial or organization can use the funds without permission. Only when the contract conditions are reached can the proceeds be automatically distributed according to the contract. And all the information on the chain is completely fair, just, open and transparent, and can't be tampered with
③ there is no need to register with mobile phone / email or ID card, as long as there is a decentralized Ethernet wallet address, you can participate in the game, and there is no leakage of any private information, and there is no security risk
④ cash at any time, and the smart contract on the chain is processed, No one, no organization approval required
⑤ never shut down the network, run on the chain, and no background management< (6) business logic is closely linked, dynamic and static distribution is reasonable, large and small reward pools promote, global shareholders are determined by quantitative performance, transparent and profiteering, lasting and stable

how to participate
① with imtoken 2.0, trustwallet, wheat, and other decentralized wallets, you can participate without additional registration< (2) exchange purchases eth or wallet stores eth; (3) exchange eth for tickets (PLT): tickets are 1 / 10 of the amount of money involved in the game<
4 login portal (block browser of major decentralized wallets)
ten highlights of mode innovation
1 Ethereum smart contract, true decentralization
2 fair, open, transparent, tamper proof
3 everyone has the opportunity to participate in enjoying the global performance branch
4 PLT destruction mechanism, with increasing value
5 low threshold investment, With the static exit of xiaoboda
6, the exit account re investment adds infinite circulation
7 eth in and out security, there is no centralized control
8 big prize pool business model, never collapse
9 small prize pool winning amount, everyone has the opportunity
10 Ethernet wallet address registration account, security protection

the era of real blockchain + smart contract has come!

6.

Generally speaking, the steps of deploying smart contract are as follows:

1. start an Ethereum node (such as geth or testrpc)

2. use Solc to compile smart contracts=& gt; Get the binary code

3. deploy the compiled contract to the network This step will consume Ethernet currency, and you need to use the default address or specified address of your node to sign the contract.)=& gt; Get the blockchain address and ABI of the contract (JSON representation of the contract interface, including variables, events and callable methods) The author confused ABI with contract interface here. ABI is the binary representation of the contract interface.)

4. use the JavaScript API provided by web3.js to call the contract Depending on the type of call, it may consume Ethernet currency.)

7.

Ledger is a book with a certain format and several account pages. Based on the accounting documents, it records all economic business in chronological order and classification, which is what we usually call the ledger. Blockchain represents a unique data record format. Blockchain is "block + Chain". The so-called block is the meaning of data block. Each block is connected by a certain mark to form a chain

Super ledger

hyperledger (Chinese name is super ledger, collectively referred to as hyperledger) is an open source project launched by Linux foundation in 2015 to promote blockchain digital technology and transaction verification. The goal of hyperledger is to enable members to work together to build an open platform to meet the needs of various users from different instries, while greatly simplifying the business process. The founding members of hyperedge include IBM, Intel, Cisco and other large companies. By the end of this book, more than 183 organizations and companies have joined hyperedge, and they are growing rapidly

at the beginning of hyperledger project, Linux foundation has received a number of different code bases, including IBM code base (inspired by Ethereum to a certain extent), Dah (bits of proof bitcoin code base) and sockstream code base (an extension of bitcoin code base). In addition, there are digital asset and ripple contributions. With the development of the instry, a single project has been unable to meet the needs of the business, so hyperledger has graally developed from a single project into a project group. At present, hyperledger is not a specific technology, but a set of blockchain technology frameworks. Up to now, the hyperledger project team contains 9 formal projects and more than 50 moles related to these formal projects

the Xueshuo innovation blockchain Technology Workstation of Lianqiao ecation online is the only approved "blockchain Technology Specialty" pilot workstation of "smart learning workshop 2020 Xueshuo innovation workstation" launched by the school planning, construction and development center of the Ministry of ecation of China. Based on providing diversified growth paths for students, the professional station promotes the reform of the training mode of the combination of professional degree research, proction, learning and research, and constructs the applied and compound talent training system

8. They are all distributed ledgers, with different degrees of application and public ownership

9. Oneledger released our MVP (minimum available proct) at the end of last month. This month, oneledger launched the atom exchange between Ethereum and bitcoin, which will be the basis of oneledger's cross chain capability.