What is the concept of Dao in Ethereum

1. Ethereum is an innovation that applies some technologies and concepts in bitcoin to the field of computing. Bitcoin is considered a system that maintains a shared account book that securely records all bitcoin bills. Ethereum uses many mechanisms similar to bitcoin (such as blockchain technology and P2P network) to maintain a shared computing platform, which can flexibly and safely run any program users want (including bitcoin like blockchain programs of course)

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2. Based on the core idea of bitcoin network, Ethereum project puts forward many innovative technical concepts, including smart contract, account based transaction, Ethereum and fuel.

3. Eth is a kind of digital token of Ethereum, which is regarded as "bitcoin version 2.0". It adopts the blockchain technology "Ethereum", which is different from bitcoin. It is an open-source public blockchain platform with intelligent contract results, and a resonance network composed of tens of thousands of computers around the world. Developers need to pay eth to support the application. Like other digital currencies, ether currency can be bought and sold on the trading platform

warm tips: the above explanations are for reference only, without any suggestions. There are risks in entering the market, so investment should be cautious. Before making any investment, you should make sure that you fully understand the nature of the investment and the risks involved in the proct. After a detailed understanding and careful evaluation of the proct, you can judge whether to participate in the transaction
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4.

Ethereum is an open source public blockchain platform with smart contract function. It provides decentralized virtual machine (Ethereum virtual machine) to process point-to-point contract through its special cryptocurrency ether (also known as "Ethereum")

The token on the

blockchain is called ether, and the code is eth. It can be traded in many foreign exchange markets of cryptocurrency, and it is also the medium used to pay transaction fees and computing services on Ethereum

the concept of Ethereum was first proposed by vitalik buterin, a programmer, from 2013 to 2014, inspired by bitcoin, with the general meaning of "next generation cryptocurrency and decentralized application platform", and began to develop through ICO crowdfunding in 2014. As of February 2018, Ethernet is the second highest cryptocurrency in market value, second only to bitcoin

extended data:

Ethereum platform has no characteristics and value. Like programming languages, it's up to entrepreneurs and developers to decide what to use. However, it is clear that some application types benefit more from the functions of Ethereum than others. Ethereum is especially suitable for those applications that automatically interact directly between points or promote group coordination activities across networks

for example, coordinate the application of point-to-point market, or the automation of complex financial contracts. Bitcoin enables indivials to exchange money without the help of financial institutions, banks or governments. The impact of Ethereum may be more profound

in theory, any complex financial activities or transactions can be automatically and reliably carried out on Ethereum with coding. In addition to financial applications, any application scenario with high requirements for trust, security and persistence, such as asset registration, voting, management and Internet of things, will be affected by Ethereum platform on a large scale

5. In the field of blockchain technology, Dao refers to the community of distributed autonomous organizations, and block is a blockchain technology community
Dao is a mechanism through which we can use software on the Internet to achieve reasonable economic incentives (allocation of risks / rewards). With Dao, people can coordinate with each other and achieve common goals on a global scale without relying on trust or a third party. Blockchain technology makes this mechanism feasible
the establishment of block community is under the background of the rapid development of blockchain, which is faced with some problems: the mainstream blockchain community focuses on media positioning, has a fickle mentality, pays attention to currency speculation and ignores the promotion and discussion of blockchain technology; After blockchain project financing, they are keen on media PR promotion, and do not solidly develop procts and build technology communities; There is no platform to focus on the development of blockchain technology, open up instry university research and government departments, and construct a complete blockchain ecosystem; There is no fair, independent and powerful third-party platform in the instry, which can objectively reflect the quality and community influence of blockchain project development
block is a community that serves blockchain developers and projects, and promotes the implementation of blockchain technology and applications.

6. This part of you:
newsservice. Java (hibernate for persistence)
{
construct session factory {
public void addnews (newsvo News) {
try {
session. Save (News)}// Save, transaction start and commit are the Dao layer. Your Dao layer is implemented with hibernate

7.

Dao class is the class for data operation,

is the code for adding, deleting, modifying and querying the data in the database

Dao (data access object) is an object-oriented database interface, which reveals the Microsoft Jet database engine (used by Microsoft Access), and allows visual basic developers to directly connect to access tables through ODBC just like other databases. Dao is most suitable for single system application or small local distribution

The interface is used to standardize the implementation class, and the implementation class is used to operate the database! In general, the steps of modifying, adding, and deleting database operations are very similar. We write a public Dao class. When modifying, adding, and deleting database operations, we directly call the public Dao class

extended data:

Dao (data access object) is a data access interface, data access: as the name suggests, it is to deal with database. Sandwiched between business logic and database resources

In the core J2EE mode, Dao mode is introced as follows: in order to build a robust J2EE application, all access operations to data sources should be abstractly encapsulated in a common API. In programming language, it is to establish an interface, which defines all the transaction methods that will be used in this application. In this application, when you need to interact with the data source, you use this interface, and write a separate class to implement this interface, which logically corresponds to the specific data store

access object

Dao (data access object) is an application programming interface (API), which exists in Microsoft's visual basic and allows programmers to request access to Microsoft's access database. Dao is Microsoft's first object-oriented database interface. Dao objects close the jet function of access. Through jet function, it can also access other structured query language (SQL) databases

8. : data access object: data access layer, which mainly stores database operation (add, delete, modify and query) related codes
biz = = business?: Business logic layer, mainly storing business logic code
util: tool class
Web: storing Java classes related to processing foreground requests

this is the hierarchical idea of MVC
the foreground sends requests to action (stored under the web package), action calls the corresponding methods of service (under the business package), and the methods in these services call the classes under the Dao package to complete business logic. Finally, the processing results are returned to the foreground.