Blockchain information map
blockchain is a new application mode of distributed data storage, point-to-point transmission, consensus mechanism, encryption algorithm and other computer technologies. Blockchain is an important concept of bitcoin,
in essence, it is 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 of bitcoin network transactions, Used to verify the validity of its information (anti-counterfeiting) and generate the next block
extended data
most blockchain public chains are limited by scalability. The biggest feature of blockchain technology is decentralization, which requires that all accounts in the network need to deal with the accounting process. Distributed accounting has high security, low misoperation rate, political neutrality and correctness
however, blockchain technology embraces these features at the same time, sacrificing scalability, unable to meet the personalized supervision, and slightly insufficient in protecting data privacy. Moreover, with the increase of the number of ledger, the interaction delay will increase exponentially, that is to say, the more ledger in the blockchain network, the higher the delay
MACD is called the moving average of similarities and differences, which is developed from the double index moving average. The fast line dif is obtained by subtracting the slow index moving average (ema26) from the fast index moving average (ema12), and then 2 × Fast line dif-dif's 9-day weighted moving average (DEA) obtained MACD column. The significance of MACD is basically the same as that of double moving average, that is, the dispersion and aggregation of fast and slow moving average represent the current long short state and the possible development trend of stock price, but it is more convenient to read. When MACD turns from negative to positive, it's a buy signal. When MACD turns from positive to negative, it's a sell signal. When MACD changes from a large angle, it means that the gap between the fast moving average and the slow moving average widens very quickly, which represents the change of a market trend.
blockchain is a digital account book that can be jointly bookkept, and will record all transactions that have occurred and have been unanimously recognized by the system it's the same as the whole family. You're bookkeeping, and your father and mother are also bookkeeping. They can see the general ledger, but the saved information can't be tampered with any more
In 2008, Nakamoto first proposed the concept of blockchain subsequently, blockchain has become the core component of electronic currency bitcoin, which serves as the public account book for all transactions. By using peer-to-peer network and distributed timestamp server, the blockchain database can be managed independentlyextended data:
type of blockchain
1, public blockchain
any indivial or group in the world can send transactions, and transactions can be effectively confirmed by the blockchain, and anyone can participate in its consensus process. Public blockchain is the earliest and the most widely used blockchain. The virtual digital currencies of bitcoin series are all based on public blockchain. There is only one blockchain corresponding to this currency in the world
2, Alliance (instry) blockchain
instry blockchain: multiple preselected nodes are designated as bookkeepers within a group, and the generation of each block is jointly determined by all preselected nodes (preselected nodes participate in the consensus process), and other access nodes can participate in the transaction, However, regardless of the bookkeeping process (in essence, it is still managed bookkeeping, only distributed bookkeeping, how many preselected nodes, and how to determine the bookkeeper of each block to become the main risk point of the blockchain), anyone else can conct limited query through the open API of the blockchain
3, private blockchain
only uses the general ledger technology of blockchain for bookkeeping. It can be a company or an indivial, and enjoys the write permission of the blockchain. This blockchain is not very different from other distributed storage schemes
The strict definition of blockchain refers to the distributed database technology that multiple nodes in peer-to-peer network jointly maintain a continuously growing list ledger constructed by time stamp and orderly record data blocks through consensus mechanism based on cryptography technology. This technical solution allows any number of nodes in the participating system to calculate and record all the information exchange data in the system in a period of time to a data block through cryptography algorithm, and generate the fingerprint of the data block for linking the next data block and checking. All participating nodes in the system jointly determine whether the record is true
blockchain is a technical solution similar to NoSQL (non relational database). It is not a specific technology, and can be implemented through many programming languages and architectures. There are many ways to realize blockchain, including pow (proof of work), POS (proof of stake), dpos (delegate proof of stake), etc
the concept of blockchain was first proposed in the paper "bitcoin: a peer-to-peer electronic cash system" by indivials (or groups) who call themselves Satoshi Nakamoto. Therefore, bitcoin can be regarded as the first application of blockchain in the field of financial payment
< H2 > [popular explanation]no matter how big the system or how small the website is, there is a database behind it. So who will maintain this database? In general, who is responsible for the operation of the network or system, then who is responsible for the maintenance. If it is wechat database, it must be maintained by Tencent team, and Taobao database is maintained by Alibaba team. We must think that this way is natural, but blockchain technology is not
if we think of the database as a book, for example, Alipay is a typical account book. Any change of data is bookkeeping. We can think of database maintenance as a very simple way of accounting. In the world of blockchain, everyone in the blockchain system has the opportunity to participate in bookkeeping. The system will select the fastest and best bookkeeper in a period of time, maybe within ten seconds or ten minutes. The bookkeeper will record the changes of the database and the account book in a block. We can think of this block as a page. After the system confirms that the records are correct, the system will record the changes of the database and the account book in a block, It will link the fingerprint of the past account book to this paper, and then send this paper to everyone else in the whole system. Then, over and over again, the system will look for the next person with fast and good bookkeeping, and everyone else in the system will get a of the whole ledger. This means that everyone as like as two peas in the system is called Blockchain. It is also called distributed account technology. P>
as like as two peas (computer) have identical accounting books, and everyone has the same rights, they will not collapse e to the loss of contact or downtime of a single person. As like as two peas, the data is transparent and everyone can see what changes are in every account. Its very interesting feature is that the data can't be tampered with. Because the system will automatically compare, it will think that the same number of books with the largest number are real books, and a small number of books with different numbers are false books. In this case, it's meaningless for anyone to tamper with his own account book, because unless you can tamper with most nodes in the whole system. If there are only five or ten nodes in the whole system, it may be easy to do so. However, if there are tens of thousands or even hundreds of thousands of nodes and they are distributed in any corner of the Internet, unless someone can control most computers in the world, it is unlikely to tamper with such a large block chain
< H2 > [elements]combined with the definition of blockchain, we think that we must have the following four elements to be called public blockchain technology. If we only have the first three elements, we will consider it as private blockchain Technology (private chain)
1, peer-to-peer network (power equivalence, physical point-to-point connection)
2, verifiable data structure (verifiable PKC system, non tampering database)
3, distributed consensus mechanism (Solving Byzantine general problem, solving double payment)
4 Game design of Nash equilibrium (cooperation is the strategy of evolutionary stability)
combined with the definition of blockchain, blockchain will realize four main characteristics: decentralized, trustless, collective maintenance and reliable database. And the other two will be derived from the four characteristics Features: open source Privacy. If a system does not have these characteristics, it can not be regarded as an application based on blockchain technology
Decentralized: there is no centralized hardware or management organization in the whole network. The rights and obligations of any node are equal, and the damage or loss of any node will not affect the operation of the whole system. Therefore, it can also be considered that the blockchain system has excellent robustnesstrustworthiness: there is no need to trust each other when participating in the data exchange between each node in the whole system. The operation rules of the whole system are open and transparent, and all data contents are also open. Therefore, within the specified rule range and time range of the system, nodes cannot and cannot cheat other nodes
collective maintenance: the data blocks in the system are maintained by all the nodes with maintenance function in the whole system, and these nodes with maintenance function can be participated by anyone
reliable database: the whole system will enable each participating node to obtain a of the complete database in the form of sub databases. Unless more than 51% of the nodes in the whole system can be controlled at the same time, the modification of the database on a single node is invalid, and the data content on other nodes cannot be affected. Therefore, the more nodes and computing power in the system, the higher the data security in the system
Open Source: since the operation rules of the whole system must be open and transparent, the whole system must be open source for the program
Privacy Protection: since there is no need to trust each other between nodes, there is no need to disclose the identity between nodes, and the privacy of each participating node in the system is protected
generally, the blockchain platform will provide corresponding interfaces, such as RPC, json-rpc, HTTP, etc. of course, the platforms are not the same, and the degree of friendliness is different
some companies specializing in API, such as blockcypher, can provide friendly calling interfaces, and it is not very convenient to write answers on the mobile phone, Search below
as for the storage content, add a point: in addition to the conventional cloud storage, file entities on the file hash record chain also have blockchain based storage schemes, such as IPFs, storej and so on
the expansion of blockchain is the general trend, but there are differences in the specific operation. According to the different levels of blockchain architecture, the instry has proposed a number of expansion solutions: first, optimize the data transmission protocol for the underlying data layer of blockchain, do not change the upper structure of blockchain, and improve the scalability, such as bloxroute, the 0-layer expansion scheme of blockchain; The second is to change the data structure and consensus algorithm to improve the scalability of the basic protocol of blockchain, such as DAG (directed acyclic graph), fragmentation, dpos algorithm, etc; Third, aiming at the application level, such as side chain, sub chain, state channel lightning network and so on, part of the on chain transactions are transferred to the off chain execution to rece the on chain processing pressure and improve the overall efficiency.