HTTP is an application layer of the face object of the protocol, simple and fast, suitable for distributed hypermedia information System. The current WWW version is 1.0 of the sixth edition http features: 1: Support client/server mode  2: Simple and fast. The client wants the server to send the request, only the request method and path are required. The requested method has get post head 3: Flexible: HTTP allows the transfer of any type of data object. 4: No connection. The meaning of no connection is to limit each link to the processing of one request. When the server finishes processing the customer's request and is answered by the customer, the link is broken. In this way, the transmission time can be saved. 5: no status. The HTTP protocol is a stateless protocol. Stateless means that the protocol has no memory ability to deal with things. A lack of state means that if the previous information is required for subsequent processing, he must retransmit. This can result in large data transfers per transmission. The http request consists of three parts: the request line, the message header, the request body http The response is also composed of three parts: status line, message header, response body Status code consists of three digits, the first number defines the category of the response. 1XX Indicate West information-indicates that the request has been accepted and continues processing. 2XX Success--Indicates that the request has been successfully received and continues processing 3xx redirection--the request to be completed must take a step further action 4xx client error--request is not implemented by syntax error or request cannot implement 5XX Server error-Server failed to implement legitimate request  HTTP Protocol related Technology supplement:: high-level protocol: FTP file Transfer Protocol, e-Mail Transfer Protocol: SMTP, Domain Name System service:dns intermediary There are three kinds: proxy, gateway, channel, Agent: Intermediate program, can act as a server. You can also act as a client to make requests for other customers. is a special network service that allows a network outage to be connected to another network terminal via a non-direct connection The computer system that provides the proxy service is known as a proxy server through other types of network terminals. Gateways: Gateways are also known as inter-network connectors, protocol converters. Gateway on the transport layer to achieve network interconnection, is the most complex network interconnection devices, only for two high-level protocols different network interconnection. A gateway is a computer system or device that acts as a transformation task. The gateway is a translator between two systems that use different communication protocols, data formats or languages, and even architectures that are completely different。 Unlike bridges, which simply convey information, the Gateway will repackage the information received to suit the needs of the intended system. The gateway can also provide filtering and security features. Most gateways run on the top layer of the OSI 7 layer protocol-the application layer. [1] The gateway as the name implies is connected to two network devices, for the Voice gateway, he can connect to the PSTN network and Ethernet, which is equivalent to VoIP, the different phones in the analog signal through the gateway and converted to digital signals, and to join the protocol to transfer.
HTTP protocol Related knowledge
