Take you step by step to understand the blockchain! (Lesson 3)

How Blockchain Works

Blockchain is a decentralized database technology, and its operation principle includes the following steps:

1. Create a transaction: The user creates a transaction, including transfer information and identity verification of both parties.

2. Verify the transaction: the node verifies whether the transaction is legal, including verifying the identity of both parties to the transaction and the integrity of the transaction.

3. Packaged transactions: Transactions that pass verification are packaged into a block.

4. Confirm the block: the block is sent to each node in the network for confirmation, and the block is added to the blockchain after the confirmation is correct.

5. Update status: The records of all transactions are stored in the blockchain, and nodes can update the status of the system according to these transactions.

6. Incentive-driven: Nodes are rewarded by verifying transactions and packaging blocks, and are incentive-driven.

The above is the basic operation process of the blockchain. Its decentralized and decentralized characteristics make the blockchain highly secure and reliable.

Blockchain programming language

There are many blockchain programming languages, the following are some common ones:

1. Solidity: Solidity is a high-level programming language for smart contract development on the Ethereum platform, similar to JavaScript.

2. Java: Java is a popular programming language for developing blockchain applications and can be used for blockchain platforms such as Hyperledger Fabric and Corda.

3. C++: C++ can be used in the development of blockchain platforms such as Ethereum and Bitcoin, with high speed and efficiency.

4. Python: Python is a concise and easy-to-read programming language that can be used for blockchain application development, such as the EOS platform.

5. Go: The Go programming language is an open source programming language developed by Google and can also be used for blockchain development, such as Hyperledger Fabric.

The above are common blockchain programming languages, and different blockchain platforms may support different programming languages.

Common blockchain development frameworks:

1. Ethereum: Ethereum is one of the most popular blockchain development frameworks. It provides Solidity programming language and smart contract development tools, and developers can build decentralized applications on it.

2. Hyperledger Fabric: Hyperledger Fabric is an enterprise-level blockchain framework that can be used to build highly scalable blockchain applications that support multiple programming languages.

3. Corda: Corda is an enterprise-level blockchain platform designed specifically for financial services, providing development support for smart contracts and decentralized applications.

4. EOSIO: EOSIO is a high-performance blockchain development framework that supports smart contracts for developing decentralized applications. 5. Quorum: Quorum is an enterprise-level blockchain framework developed by JP Morgan Chase. It is based on Ethereum and designed specifically for financial institutions, providing high scalability and privacy.

The above are several common blockchain development frameworks, and developers can choose the appropriate framework according to specific needs.

Common blockchain open source projects and literature:

1.Bitcoin: Bitcoin is the first blockchain project whose source code is open source and available on GitHub.

2. Ethereum: Ethereum is an open source blockchain platform whose source code is also available on GitHub.

3. Hyperledger Fabric: Hyperledger Fabric is an enterprise-level blockchain open source project hosted by the Linux Foundation, and its source code can also be found on GitHub.

4. Corda: Corda is an open source enterprise-level blockchain platform led by R3, whose source code is also available on GitHub.

5. Mastering Bitcoin: "Mastering Bitcoin" is an open source book written by Andreas Antonopoulos, which introduces the basics and principles of Bitcoin and blockchain.

6. Ethereum Whitepaper: The Ethereum Whitepaper is an open source archive written by Vitalik Buterin, which introduces the design and technical principles of Ethereum.

7.Bitcoin Whitepaper: The Bitcoin Whitepaper is an open source archive written by Satoshi Nakamoto, which introduces the design and technical principles of Bitcoin.

The above are some common blockchain open source projects and documents, which will help developers understand the basic knowledge and principles of blockchain technology.

To write a blockchain, you need to understand its basic structure and operating principles, including blocks, transactions, consensus mechanisms, etc., and then choose a suitable programming language and development framework for development. At the same time, you need to consider factors such as security and efficiency. It is recommended to refer to relevant open source projects and literature for practice and optimization.

Developing a blockchain requires a combination of multiple technologies. Here are some basic steps:

1. Select a blockchain platform: According to specific needs, choose a suitable blockchain platform, such as Ethereum, Hyperledger Fabric, Corda, etc.

2. Choose a programming language: According to the selected blockchain platform, choose a suitable programming language, such as Solidity, Go, Java, etc.

3. Design data structure: Blockchain uses data structure to store transaction and state information. According to the requirements, design a suitable data structure.

4. Write smart contracts: Smart contracts are codes on the blockchain that are used to implement transactions and business logic. According to requirements and design, write smart contracts.

5. Design nodes and networks: Blockchain uses nodes and networks to achieve the characteristics of decentralization and distribution. Based on requirements and design, design nodes and network.

6. Testing and deployment: Test the function and performance of the blockchain project, and deploy to the selected blockchain platform and network.

Developing a blockchain is a complex process that requires an in-depth understanding of blockchain technology and related programming languages ​​and tools.

Blockchain technology, as a decentralized digital recording technology, has been widely used in various fields. Its core features are decentralization, immutability and irreversibility, which can ensure the security and transparency of transactions. The following is an example of a blockchain application:

Assume that in a supply chain management system, there are multiple participants, including producers, wholesalers, retailers and consumers, who conduct commodity transactions among them. In order to ensure the transparency and security of transactions, this supply chain system uses blockchain technology to track and record commodities.

When a manufacturer produces a batch of goods, he will record the relevant information of the goods (such as production date, production batch, product specifications, etc.) into a new block on the blockchain. Next, when the batch of goods is shipped to the wholesaler, the wholesaler will add the receipt information of the goods to the same block on the blockchain, and at the same time update the inventory information of the goods.

When this batch of goods is shipped to the retailer, the retailer will also add the receipt information to the same block and update the inventory information of the goods at the same time. Finally, when a consumer purchases this batch of goods, he can view the production and circulation process of the goods from the blockchain.

The following is an example of a simple blockchain smart contract written in the Solidity programming language:

1pragma solidity ^0.8.0;

2

3contract SupplyChain {

4 // product structure

5 struct Product {

6 uint256 productId;

7 string productName;

8 uint256 productBatch;

9 uint256 productPrice;

10 address producer;

11 address wholesaler;

12 address retailer;

13 address consumer;

14}

15

16 // Item number

17 uint256 productId = 0;

18

19 // Product mapping, used to store product information

20 mapping(uint256 => Product) products;

twenty one

22 // The manufacturer adds new products

23 function addProduct(string memory productName, uint256 productBatch, uint256 productPrice) public {

24 productId++;

25 products[productId] = Product(productId, productName, productBatch, productPrice, msg. sender, address(0), address(0), address(0));

26}

27

28 // Wholesaler buys goods

29 function buyFromProducer(uint256 _productId) public payable {

30 Product storage product = products[_productId];

31 require(msg. value == product. productPrice, "Insufficient payment.");

32 product.wholesaler = msg.sender;

33 product.producer.transfer(msg.value);

34}

35

36 // The retailer buys the item

37 function buyFromWholesaler(uint256 _productId) public payable {

38 Product storage product = products[_productId];

39 require(msg. value == product. productPrice, "Insufficient payment.");

40 product. retailer = msg. sender;

41 product.wholesaler.transfer(msg.value);

42}

43

44 // Consumer buys goods

45 function buyFromRetailer(uint256 _productId) public payable {

46 Product storage product = products[_productId];

47 require(msg. value == product. productPrice, "Insufficient payment.");

48 product.consumer = msg.sender;

49 product. retailer. transfer(msg. value);

50}

51

52 // Query product information

53 function getProduct(uint256 _productId) public view returns (uint256, string memory, uint256, uint256, address, address, address, address) {

54 Product storage product = products[_productId];

55 return (product. productId, product. productName, product. productBatch, product. productPrice, product. producer, product. wholesaler, product. retailer,

product.consumer);

}

}

The above is a simple blockchain smart contract example, which is used to realize the basic functions of the supply chain management system. These include functions such as adding new products, purchasing products by wholesalers, purchasing products by retailers, purchasing products by consumers, and querying product information. The program uses the Solidity programming language, and uses functions such as structures, mappings, and decorators. Through the execution of smart contracts on the blockchain, the transparency and security of supply chain information can be achieved.