Network of test and development - Common Service Protocols

agreement , It's short for network protocol , Network protocol is a set of agreement that both sides of communication computer must comply with . How to establish a connection 、 How to identify each other, etc . Only by following this Agreement , Computers can communicate with each other . The three elements of it are ： grammar 、 semantics 、 sequential . (1) grammar ： That is, the structure or format of data and control information ; (2) semantics ： That is, what kind of control information needs to be sent , What actions to complete and what responses to make ; (3) sequential （ Sync ）, That is, a detailed description of the sequence of event implementation .

TCP/IP

TCP/IP Protocol is the protocol used in today's Internet . It's not just about TCP、IP Two parts , But by the FTP、SMTP、TCP、UDP、IP And so on .TCP/IP Of the agreement 4 layer - The network layer , Responsible for creating network connection between hosts , And the completion of IP Addressing and forwarding function of .

DNS

DNS（Domain Name System, The domain name system ） It's a domain name resolution service . It resolves the domain name into IP Address , In order to facilitate the use of easy to remember English letters , To access the Internet . The following example completes a parse , adopt ping domain name , We can get it IP Address .

Local domain name resolution

Except with the help of DNS, When we access internal servers through domain names , You can use local HOSTS File to complete the domain name resolution , Note that this process takes precedence over DNS Of . Windows The next file is C:\WINDOWS\system32\drivers\etc\hosts,Linux Next in /etc/hosts, Here is an example .

DHCP

DHCP（Dynamic Host Configuration Protocol, Dynamic Host Configuration Protocol ） It is used to dynamically allocate available IP Address . stay Windows Next , Use ipconfig command , You can view the assigned IP Address ,Linux Please use the ifconfig Instead of .

Two are shown here IP Address ：

• lo0 127.0.0.1 Is the loopback address used for internal communication of this machine . It's the same for every machine 、 Permanent virtual machine local IP Address ;
• en0 192.168.0.100 yes DHCP The server's dynamic allocation for the first Ethernet card IP Address . When the machine is shut down ,DHCP It'll be for the machine （ network card ） Keep this address for a while .

HTTP/HTTPS

HTTP（HyperText Transfer Protocol, Hypertext transfer protocol ） It's the most widely used protocol on the Internet . This article you are reading in your browser , This is the protocol used to transmit .HTTPS On the basis of it , Implemented encryption . HTTP/HTTPS It's a connectionless 、 Stateless application layer protocol . in other words , The browser sends a request to the server through it to get the response , The connection is closed . Between the browser and the server , It uses a method called Session（ conversation ） The mechanism of , When the next request comes , The server still knows who the visitor is . Server identification Session Methods , It's usually a request URL or Header A unique identification carried in （ Such as jsessionid、bearer token、cookie） To work . Next, when we introduce interface testing , We'll go further .

WebSocket

WebSocket Establish a persistent connection between the client and the server , Allows the server to actively push data to the client , To achieve real-time two-way data transmission . It solves the problem of using in the past HTTP When the agreement , You can only pull data , Or use HTTP When simulating long connections ,Long Polling The problem of excessive consumption of resources . WebSocket It's the application layer protocol , yes TCP/IP A subset of protocols , It connects through HTTP Agreement complete handshake .

RPC

RPC（Remote Procedure Call Protocol, Remote procedure call protocol ） Most of them are used in the current popular microservice architecture , It is convenient for one computer to call the program on another directly , You don't need to know the underlying network technology / agreement .RPC Can be based on HTTP（ application layer ） agreement , You can also directly TCP（ Transport layer ） The protocol realizes