Vocational College blockchain
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
legal representative: Ma Xiaofeng
time of establishment: May 18, 2017
registered capital: RMB 1 million
business registration number: 320507000330320
enterprise type: limited liability company
address: 11-12 / F, Lingyu Business Plaza, 66 qinglonggang Road, high speed rail new town, Xiangcheng District, Suzhou
2018 has entered the countdown, and the first year of blockchain is coming to an end. In 2018, blockchain technology has received great attention all over the world, and the governments of various countries are actively making efforts in the field of blockchain in an attempt to seize the commanding height of the next instrial innovation. According to the blockchain instry yearbook, in terms of talent supply, there is a large shortage of blockchain talents, and there is a high demand for compound talents. In addition to social training and training, colleges and universities have started blockchain courses
for example, Stanford University, Massachusetts Institute of technology and University of California, Berkeley have begun to offer courses related to blockchain or digital currency. Moreover, many online courses and large-scale open online courses also began to provide relevant training services
it is true that as a "young" technology, the main force of future development of blockchain technology is bound to be young people. But at present, many practitioners in the blockchain instry are self-taught, without systematic professional knowledge training, or only one-sided talents in cryptography, programming, Internet technology, etc
and blockchain technology pays more attention to compound talents with multiple technologies, which may be the internal reason why blockchain talents are increasingly becoming just needed. In 2019, blockchain technical talents seem to have become new professionals, and will be highly competitive
If bitcoin represents blockchain version 1.0, it proves to the world that digital currency can be realized. Then Ethereum represents blockchain version 2.0, which lets you know more about the play of blockchain, decentralized applications and smart contracts. In 2018, blockchain will enter the stage of 3.0, application and scenario landing will be the core of blockchain, and blockchain based applications in various instries will spring up, which will be the early dividend period of the last stage of blockchain development. The demand for talents driven by the application of blockchain technology has become increasingly large. Blockchain technical talents have become the new professional talents, which are highly competitive, and also have enviable high salaries
whether to form a meaningful large-scale consensus: one of the outstanding advantages of blockchain is that it can effectively form a large-scale consensus by opening account books and notifying the whole network. At present, there is no need to form a network wide consensus for many projects. Some projects are just for crowdfunding and token issuance. The blockchain consensus of projects is meaningless. Does this model have network effect: network effect means that a project will become more and more valuable with more and more users of the project, because the value of the project is not in the users themselves, but in the connection network between users. Bitcoin is a typical example. The more user nodes there are, the more links between nodes will grow exponentially, and the whole ecosystem of bitcoin will be more valuable
of course, in addition to these points, there are many basic principles to judge the project, such as effective incentive mechanism, strong team, project solving pain points, and so on
The deposit fee of 100 yuan for registration can be returned after completing all courses
tutoring class was given under the line, and the lecture lasted for 4 days, with 7800 yuan per person
RMB 88888 per person for 3 days and 2 nights
What is...
blockchain? Maybe few people can really answer this question. It is precisely because of the inherent mystery of "blockchain", that many people are eager to pay for knowledge in order to get on the train to the "future"
therefore, all kinds of blockchain training are also very popular, and all kinds of information, such as "scanning code, entering the group to listen to lectures", are filled with the circle of friends, so it is difficult to distinguish the good from the bad. The training costs are even more uneven: 100 yuan, 300 yuan, 7000 yuan or even nearly 100000 yuan...
blockchain training is too hot
I often make up my identity on the dating materials, such as import lighting wholesalers, urban landscape designers, boutique tobacco hotel owners and agricultural loan salesmen. Now, I have finally become an expert in blockchain training courses
} photo source: a screenshot of a recruitment website
and it is reported that a blockchain recruitment advertisement in Beijing recently blew up the circle of friends, requiring candidates to have in-depth research on blockchain technology and cryptography, giving an annual salary of not less than 5 million yuan, and not capped
"this is really the current situation of blockchain talent recruitment. But even so, we can't find people, because it's hard to find qualified people. " Lu Sheng, head hunter of Liepin platform, said
Song Mofei, senior researcher of Suning Institute of finance, said: "in terms of development experience, the rise of domestic blockchain instry has been concentrated in the last two or three years, and few people have long-term blockchain development experience in the talent market." He believes that excessive salary will inevitably attract some speculators, but the increase of salary does not bring about the increase of the application threshold, and even some recruiters only know a little about blockchain technology, which also poses new challenges for the recruitment of blockchain talents
according to Shan Yi, chief data officer of liepin.com, the core of blockchain is the change of social relations and business model based on Internet distributed trust system, which is characterized by decentralization“ There are still many uncertainties in the future development of block chain. There are obvious bubbles at present, and many block chain projects are not reliable. He said
the main protocols are as follows: 1. IP internet protocol IP is the heart of TCP / IP and the most important protocol in the network layer. The IP layer receives the data packet from the lower layer (network interface layer, such as Ethernet device driver) and sends the data packet to the higher layer -- TCP or UDP layer; On the contrary, IP layer also transfers packets received from TCP or UDP layer to lower layer. IP packets are unreliable because IP doesn't do anything to confirm that the packets are sent in order or are not corrupted. IP packet contains the address of the host sending it (source address) and the address of the host receiving it (destination address). When high-level TCP and UDP services receive packets, they usually assume that the source address in the packet is valid. It can also be said that IP addresses form the authentication basis of many services, which believe that packets are sent from a valid host. IP confirmation contains an option called IP source routing, which can be used to specify a direct path between the source address and the destination address. For some TCP and UDP services, IP packets using this option seem to be delivered from the last system on the path rather than from its real location. This option exists for testing purposes, indicating that it can be used to spoof the system to make normally forbidden connections. Then, many services that rely on IP source address for confirmation will have problems and will be illegally intruded. 2. TCP if there are already sealed TCP packets in IP packets, then IP will "up" them to the TCP layer. TCP sorts packets and checks for errors, and realizes the connection between virtual circuits. TCP packets include sequence number and acknowledgement, so packets not received in order can be sorted, while damaged packets can be retransmitted. TCP sends its information to higher-level applications, such as telnet's server and client. Applications send information back to the TCP layer in turn, and the TCP layer sends them down to the IP layer, device drivers and physical media, and finally to the receiver. Connection oriented services such as Telnet, FTP, rlogin, X windows, and SMTP require a high degree of reliability, so they use TCP. DNS uses TCP (send and receive domain name databases) in some cases, but uses UDP to send information about a single host. 3. UDP is in the same layer as TCP, but it doesn't care about the order, error or retransmission of packets. Therefore, UDP is not used for connection oriented services that use virtual circuits. UDP is mainly used for query response oriented services, such as NFS. Compared with FTP or Telnet, these services need to exchange less information. Services that use UDP include NTP (Network Time Protocol) and DNS (DNS also uses TCP). Spoofing UDP packets is easier than spoofing TCP packets because UDP does not establish an initial connection (also known as handshake) (because there is no virtual circuit between the two systems), that is, UDP related services are at greater risk. 4. ICMP ICMP is located in the same layer as IP, which is used to transmit IP control information. It is mainly used to provide information about the path to the destination address. ICMP's "redirect" information informs the host of a more accurate path to other systems, while the "unreachable" information indicates that there is a problem with the path. In addition, if the path is not available, ICMP can terminate the TCP connection "gracefully". Ping is the most commonly used ICMP based service. 5. Port structure of TCP and UDP TCP and UDP services usually have a client / server relationship. For example, a telnet service process starts to be idle on the system, waiting for connection. The user uses the telnet client to establish a connection with the service process. The client program writes information to the service process, the service process reads the information and sends a response, and the client program reads the response and reports it to the user. Therefore, the connection is plex and can be used for reading and writing. How do multiple telnet connections between two systems confirm and coordinate with each other? A TCP or UDP connection uniquely uses the following four items in each message: the source IP address, the IP address of the sending packet. Destination IP address the IP address of the received packet. Source port the port of the connection on the source system. Destination port the port of the connection on the destination system. Port is a software structure, which is used by client program or service process to send and receive information. A port corresponds to a 16 bit number. Service process usually uses a fixed port, for example, SMTP uses 25, xwindows uses 6000. These port numbers are "well known" because these addresses and destination addresses are needed to communicate when establishing a connection to a particular host or service
reference model
TCP / IP protocol does not fully conform to OSI's seven layer reference model. The traditional open system interconnection reference model is a seven layer abstract reference model of communication protocol, in which each layer performs a specific task. The purpose of this model is to make all kinds of hardware communicate with each other at the same level. These seven layers are: physical layer, data link layer, network layer, transport layer, session layer, presentation layer and application layer. The TCP / IP communication protocol adopts a four layer hierarchical structure, and each layer calls the network provided by its next layer to fulfill its own requirements. These four layers are: application layer: the layer of communication between applications, such as simple e-mail transfer (SMTP), file transfer protocol (FTP), network remote access protocol (telnet), etc. Transport layer: in this layer, it provides data transmission services between nodes, such as transmission control protocol (TCP), user datagram protocol (UDP), etc. TCP and UDP add transmission data to the packet and transmit it to the next layer. This layer is responsible for transmitting data and determining that the data has been delivered and received. Interconnection network layer: it is responsible for providing basic packet transmission function, so that each packet can reach the destination host (but not check whether it is received correctly), such as Internet Protocol (IP). Network interface layer: manage the actual network media, define how to use the actual network (such as Ethernet, serial line, etc.) to transmit data
the reason why TCP / IP is a protocol family is that TCP / IP protocol includes TCP, IP, UDP, ICMP, rip, telnet FTP, SMTP, ARP, TFTP and many other protocols, which are collectively called TCP / IP protocol. Here we introce the English names and uses of some common protocols in the protocol family: TCP (Transport Control Protocol), IP (Internet Protocol), UDP (User Datagram Protocol), ICMP (Internet control message protocol) and SMTP (Simple Mail Transfer Protocol) Protocol SNMP (Simple Network Management Protocol) FTP (File Transfer Protocol) ARP (address resolution protocol) address resolution protocol from the perspective of protocol layered model, TCP / IP consists of four layers: network interface layer, inter network layer, transport layer and application layer. Among them: network interface layer, which is the lowest layer of TCP / IP software, is responsible for receiving IP datagrams and sending them through the network, or receiving physical frames from the network, extracting IP datagrams and giving them to the IP layer. The inter network layer is responsible for the communication between adjacent computers. Its functions include three aspects. 1、 After receiving the request, the packet is loaded into the IP datagram, the header is filled, the path to the destination machine is selected, and then the datagram is sent to the appropriate network interface. 2、 Processing input datagram: first check its validity, and then carry out pathfinding - if the datagram has arrived at the sink machine, remove the header and hand over the rest to the appropriate transport protocol; If the datagram has not arrived at the sink, the datagram is forwarded. 3、 Deal with path, flow control, congestion and other issues. The transport layer provides communication between applications. Its functions include: 1. Format information flow; 2、 Provide reliable transmission. In order to realize the latter, the transport layer protocol stipulates that the receiver must send back an acknowledgement, and if the packet is lost, it must be retransmitted. The application layer provides users with a set of common applications, such as e-mail, file transfer access, remote login and so on. Telnet uses telnet protocol to provide interfaces registered on other hosts in the network. Telnet session provides character based virtual terminal. File transfer access FTP uses FTP protocol to provide file function between machines in the network. We have learned the related concepts of OSI reference model. Now let's take a look at how TCP / IP protocol implements the network model compared with the seven layer protocol reference model. Layer functions in OSI: TCP / IP protocol family
application layer file transfer, e-mail, file service, virtual terminal, TFTP, HTTP, SNMP, FTP, SMTP, DNS, rip, telnet
presentation layer data format, code conversion, There is no protocol for data encryption
there is no protocol for session layer to release or establish contact with other nodes
the transport layer provides end-to-end interfaces TCP, UDP
the network layer selects routing IP, ICMP, OSPF, BGP, IGMP, ARP, RARP for data packets
the data link layer transmits addressable frames and error detection functions slip, CSLIP, PPP, MTU
the physical layer transmits data iso2110 and IEEE802 on the physical media in the form of binary data. Ieee802.2
data link layer includes hardware interface and protocols ARP and RARP
crude oil index refers to a combination of the main contracts of the NYMEX light and low sulfur crude oil futures contract. When the main contract is in the period of 1-12 months, the price of that month will be used for the quotation of crude oil index. The world crude oil trade has formed three major markets in North America, Europe and Asia. Each market has price index crude oil, namely WTI crude oil, Brent crude oil in the North Sea and Du crude oil from the Middle East. Among them, the best quality is the futures price of WTI crude oil. WTI refers to the light crude oil from West Texas, which is a common crude oil futures price in North America. Due to the U.S. military and economic capabilities in the world, WTI crude oil has become the benchmark of global crude oil pricing
P / E ratio is the ratio of market price per share to earnings per share of a stock. Market widely talked about P / E ratio, usually refers to the static P / E ratio, which is usually used as an indicator to compare whether stocks with different prices are overvalued or undervalued. It is not always accurate to measure the quality of a company's stock with P / E ratio. It is generally believed that if the price earnings ratio of a company's stock is too high, the price of the stock is bubble and its value is overvalued.
when compared with other virtual currencies, bitcoin always mentions "21 million fixed output". In the early years, bitcoin had not been exposed to investors in a large area. It proced a lot and g a lot, but there was no demand. But now purchase bitcoin, the price is expensive, the output is small, the demand is big
we believe that when there is an imbalance between supply and demand, the price of goods will be affected. Influenced by the policy, many bitcoin holders are now keeping a wait-and-see attitude. The decrease of bitcoin in circulation in the market and the increasing demand for bitcoin in the market are bound to push the price up, but in fact, it will not be the investment speculators who come into the market at this high level who will benefit in the end
popularization of regional chain
the report released by professional institutions mentioned the problem of regional chain technology. The report shows that by 2027, the global investment value of regional chain technology will reach 300 billion to 400 billion US dollars. And the regional chain as an infrastructure development, will be applied to more and more scenarios
at that time, whether the popularity of regional chain will raise the price of bitcoin is also full of uncertainty
investor confidence remains unchanged
although many institutions and financial giants are short of bitcoin, investors are still confident in the future value of bitcoin. After all, in history, is there any trading proct that can soar 7.54 million times in eight years
professional agency analysts said that 10 years ago, the impact of the financial crisis had so far failed to get rid of the shadow of many countries, and the share price bubble continued to expand. Investors would worry whether the original financial system would collapse again. Bitcoin, which has a strong performance, will attract more investors with capital inflows, thus driving up prices. In a way, bitcoin is already a safe haven
although the trading of bitcoin was suspended by China in September 2017, bitcoin surged by more than 233% after de Sinicization< In November 2017, bitcoin began to hard bifurcate, that is to say, dividing the regional chain into two, which is equivalent to doubling the issue of bitcoin, which means that the value of bitcoin will be diluted. Affected by the impending start of hard bifurcations, bitcoin started on November 9, 2017 and has been in a state of decline for four days
the suspension of the 2x fork originally scheled for November 16, 2017 has eased the anxiety of the whole bitcoin instry chain over capacity expansion, and the market is a little relieved of the possible collapse crisis caused by the fork.