Reflections on learning blockchain for beginners

2. Do you want to learn blockchain development technology or just want to know what blockchain is? If it is the former, you can look at the code of other blockchain projects and learn about it first. If it is the latter, we can pay attention to some good blockchain we media. Blockchain is an emerging instry. There is no ready-made training course. It depends on self exploration and understanding.

3. In a word, blockchain is essentially a decentralized database
whether it's the introction in the network, the answers given by everyone, or the simple and easy to understand introction, you may not really understand blockchain. It's recommended to read more relevant information to understand its landing application. Cryptofinance focuses on blockchain information

4. A brief review of the origin of blockchain
blockchain is the underlying system of distributed ledger in bitcoin. Bitcoin ledgers are built in a distributed and spontaneous way. Anyone can generate new currency blocks by performing specific cryptographic calculations, so as to obtain a digital "currency" that can be used for transactions. Bitcoin's impact on the world monetary system can be said to be subversive, which is also an important reason why it has attracted a lot of people's strong attention since it came out. After that, there were dozens of similar electronic currencies such as
"lightcoin". The abstract extraction of distributed digital currency technology from bitcoin forms a "blockchain" technology, which can be used in more fields
the basic idea of blockchain is to establish a network-based public ledger (data block), each block contains the information of a network transaction. All the participating users in the network work together to keep accounts and check accounts. All the data are open and transparent, and can be used to verify the effectiveness of the information. In this way, the authenticity and non tamperability of information can be guaranteed at the technical level without the central server as the trust intermediary
the significance of blockchain lies in "decentralization", which can fundamentally solve the fraud and rent-seeking phenomenon in value exchange and transfer by building a more reliable network system. With the popularization of blockchain technology, the digital economy will be more authentic, and the economic society will become more fair and transparent
not only digital currency, but also blockchain technology is infiltrating into more innovative fields.
virtual digital currency such as bitcoin is just an application scenario of blockchain technology. Theoretically speaking, based on the characteristics of blockchain technology, human beings can create a very rich form of services and procts, such as finance, government, enterprises, etc There are a large number of scenarios suitable for blockchain technology in cross instry and other fields, with broad prospects. At present, many countries around the world have started the research of blockchain technology, and a series of instry organizations and alliances have been established. However, as blockchain technology is a brand-new technology, which subverts the traditional centralized mode, major institutions are still in the research stage, with only a small number of actual projects landing, and the great development of the instry has just begun
now, blockchain economy is on the eve of outbreak. The exploration of financial instry is ahead of others, while the application of other instries is developing rapidly. The obvious advantage of blockchain instry application is to optimize business process, rece operation cost and improve collaborative efficiency. This advantage has been graally reflected in financial services, Internet of things, public services, social welfare and supply chain management
as the backbone of emerging technologies, blockchain is not only used in the field of virtual currency, but also in other fields such as finance, medical care, intellectual property certification, etc. a large number of excellent enterprises have emerged in China to explore or enter the blockchain instry. According to the in-depth analysis report on business model innovation and investment opportunities of blockchain instry released by foresight Instry Research Institute, as of the end of 2016, there were 105 blockchain related enterprises in China, 80% of which were concentrated in eastern coastal cities, including Shanghai, Hangzhou and Taipei
from the perspective of global blockchain technology application development, as of April 2017, financial service companies accounted for 55.43% of the 267 blockchain venture capital companies; From the perspective of the Chinese market, 34 of the top 50 blockchain venture capital companies in 2016 are involved in financial services, mainly in cross-border payment, bill discounting and financial service platform<
analysis of the development trend of blockchain
the combination of blockchain and cloud computing is more and more close, and baas is expected to become a public trust infrastructure
cloud computing is the general trend. We believe that the combination of blockchain and cloud is also an inevitable trend. There are two modes for the combination of blockchain and cloud, one is blockchain in the cloud, the other is blockchain in the cloud. The latter, namely baas, blockchain-as-a-service, refers to that the cloud service providers directly provide blockchain as a service to users. In the future, more and more cloud service enterprises will integrate blockchain technology into the ecological environment of cloud computing. By providing baas function, they can effectively rece the deployment cost of enterprise application blockchain and rece the initial threshold of innovation and entrepreneurship
the security problem of blockchain has become increasingly prominent, and security protection needs the overall consideration of technology and management
blockchain system is almost perfect mathematically, with the advantages of openness and transparency, difficult to tamper, reliable encryption, anti DDoS attack, etc. However, from the engineering point of view, its security is still restricted by infrastructure, system design, operation management, privacy protection and technology update iteration. In the future, we need to consider the overall situation of technology and management, strengthen basic research and overall protection, so as to ensure the application security
the competition of blockchain is becoming increasingly fierce, and patent competition has become an important field of competition
with the increase of participants, the competition of blockchain will become more and more fierce, and the competition is all-round, including technology, mode, patent and other dimensions. We believe that in the future, enterprises will strengthen the layout of blockchain patents. Since 2014, the number of blockchain patent applications has grown explosively. Blockchain patents are mainly distributed in the United States in North America, the United Kingdom in Europe, China and South Korea in Asia, and this pattern will be maintained in the future. The patent gap between China and the United States is narrowing, and the number of applications in China in 2016 has surpassed that in the United States. It can be predicted that the patent competition of blockchain will become increasingly fierce in the future
with the acceleration of domestic policy process, the development of the instry ushers in a new opportunity
blockchain has attracted attention from all walks of life e to its core advantages of high performance, high security, high-speed access, efficient operation and so on. In the context of the rapid development of blockchain, China conforms to the needs of globalization, closely follows the international pace, and actively promotes the research, standardization and instrialization development of domestic blockchain related fields
trustworthiness is the core requirement of blockchain, and the importance of standards and specifications is becoming increasingly prominent
in the future value delivery network based on blockchain, we will completely use algorithms and software to build the trust foundation. However, we believe that this is far from enough, and we need the standard to increase the credibility of the blockchain. In the future, the standard of blockchain will standardize the technology and governance of blockchain from the perspective of users, business oriented, and from the dimensions of smart contract, consensus mechanism, private key security, and authority management, so as to enhance the credibility of blockchain and add weight to the trust of blockchain.

5. Recommend an introctory book, blockchain, written by Zhang Jian, and then you can read more information about blockchain. In fact, you can understand the current market. If you want to speculate in money, you can download a blockchain app store first, which collects all the necessary software for money speculation in the market, including trading house, wallet, information, community and other software. It is not particularly convenient for users who want to get started. You can search the Internet for beestore.

7. There are almost all of them on the Internet, but the content is not well distributed, so it must be a new technology. In depth understanding can be obtained through some R & D companies and blockchain media, such as Heshu software, blockhouse, Heshu media, blockchain 110 and other websites. I hope I can help you. Thank you

8. 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. The 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 between nodes and communication services between applications. Its main functions are data format, data confirmation and loss retransmission. 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, which 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 (host network layer): receive IP packets and transmit them, receive physical frames from the network, extract IP datagrams and transfer them to the next layer, manage the actual network media, and define how to use the actual network (such as Ethernet, serial line, etc.) to transmit data. TCP / IP protocol structure diagram
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

9. Blockchain technology involves a wide range of disciplines and contents, including network communication, data storage, data encryption, consensus mechanism, security mechanism, cryptography and other related contents. Only by comprehensively mastering these knowledge can we better master the blockchain technology. In addition, the most important thing for learning blockchain technology is to use blockchain in practice, and the real purpose of learning technology is to develop applications that are helpful to life and proction. Xuanling technology has been committed to the development of blockchain technology related applications, and has an experienced development team. If you have relevant intention, you can contact the official website.

10. The popularity of bitcoin has caused a lot of upsurge to study the application of blockchain technology. In the recent September Shenzhen International 5g chain Electronic Exhibition / blockchain exhibition, I saw a company, hashton blockchain company, doing blockchain ecation and training, upgrading by grades, going to advanced class, and going to study for a year out of work.