HTTP protocol Learning Notes

* Browser Browse Web Links basic Processing process:

1. Resolve the host name in the URL

2. Resolving host names to IP addresses through DNS

3. Resolve the port address in the URL (default 80)

4. Establishing a TCP connection with the server

5. The browser sends an HTTP request message to the server after the connection acknowledgement is received

6. Server Reply Response message

7. Close the browser's TCP connection to the server, and the browser displays the document

* OSI (Open System interconnection Reference model) models:

1. Application layer: HTTP,HTTPS,FTP,TELNET,SSH,SMTP,POP3, etc.

2. Presentation layer: Converts the data into a format that is compatible with the recipient's system format and is suitable for transmission. (deprecated)

3. Session Layer: Responsible for setting up and maintaining the communication connection between two computers in the computer network in the data transmission. (deprecated)

4. Transport layer: The transmission header (TH) is added to the data to form a packet. The transport header contains the sending information such as the protocol used. such as TCP, UDP, TLS\SSL, PPTP, etc.

5. Network layer: Determine the path selection and forwarding of the data, add the network header (NH) to the packet to form a grouping. such as IP, ICMP, RIP, BGP, etc.

6. Data Link layer: Responsible for network addressing, fault detection and error modification. Frames are formed when the header and footer are added to the packet. The Data Link header (DLH) is a method that contains the physical address and error detection and modification. The Data Link footer (DLT) is a string that indicates the end of the packet. such as Ethernet, Wireless LAN (Wi-Fi) and general Packet Radio Services (GPRS).

7. Physical layer: The transfer of frames on local LAN, it is responsible for the management of computer communication equipment and network media interoperability. Includes pins, voltages, cable specifications, hubs, repeaters, network cards, host adapters, and more

* TCP/IP provides: error-free data transmission, sequential transmission, non-segmented traffic.

* URL Universal Naming format:<scheme>://<user>:<password>@

* URLs are commonly escaped notation to represent unsafe characters :% followed by two hexadecimal digits that represent the ASCII code of the character. Sometimes it is not possible to enter unsafe characters directly, but in order to maintain canonical form, it is advisable for the client application to convert all unsafe or restricted characters before sending any URLs to other applications. Each component of a URL will have its own secure/unsafe character (in relation to the scheme), so only the application that receives the URL from the user can determine which characters need to be encoded.

* Common Scenario Format:

common scenarios and their descriptions

http	Hypertext Transfer Protocol Scheme, in addition to no user name and password, in line with the common URL format, the default port is 80. Basic format: http://
Https	The difference from HTTP is that SSL is used to provide an end-to-end encryption mechanism for HTTP connections with a default port of 443. Basic Format:https://
mailto	It points to an email address (which does not point to any object that can be accessed directly). Basic Format:mailto:<e-mail-addr>
Ftp	The file Transfer Protocol URL can be used to download or upload files from an FTP server, and to obtain a list of directory structure contents on the FTP server. Basic Format:ftp://<user>:<password>@
Rtsp,rtspu	The RTSP URL is a audio/video Media Resource identifier that can be parsed through the live streaming protocol (real time streaming Protocol). Basic Format:rtsp://<user>:<password>@ Rtspu://<user>:<password>@
File	The file represents the files that can be accessed directly on a specified host. If you omit the host name, the default is the local host that is using the URL. Basic Format:file://
News	News is used to access some specific articles or newsgroups. The news URL itself contains insufficient information to locate the resource and does not provide a hostname or machine name for the interpreter to obtain such information. Basic Format:news:<newsgroup> news:<news-article-id>
Telnet	Telnet is used to access the interactive business, not the object itself, but an interactive application that can be accessed through the Telnet protocol. Basic format: telnet://<user>:<password>@

HTTP protocol Learning Notes