Schematic HTTP NOTE Summary

The first chapter is about Web and Network Foundation

The Web page is displayed by obtaining information such as a file resource (Resource) from the Web server side, based on the Url,web browser specified in the Address bar of the Web browser (Web client).

Tim Berners-lee, a CERN (CERN), Berners a vision that would allow researchers to share knowledge in distant places.

The basic idea originally conceived: the use of hypertext (hypertext), which is interconnected by multiple documents, is the WWW (World Wide Web), which can be mutually refer to each other.

3 www construction techniques have been proposed, namely:

Use SGML as the HTML for the text markup language of the page;

HTTP as the document delivery protocol;

Specifies the URL of the address where the document is located.

The advent of the current HTTP protocol as long as it is to solve the problem of text transmission. Since the protocol itself is very simple, a lot of application methods are conceived and put into use on this basis. Now the HTTP protocol is beyond the confines of the web framework and is being used in a variety of scenarios.

Commonly used networks (including the Internet) operate on the basis of the TCP/IP protocol family. and HTTP belongs to a subset inside it.

The combination of protocols associated with the Internet, like this, is always called TCP/IP.

The important point in the TCP/IP protocol family is layering. The TCP/IP protocol family is hierarchical: application layer, Transport layer, network layer and data link layer respectively.

Application layer: Determines the activity that communicates when the user is provided with an app service. This includes FTP services, DNS services, HTTP protocols, and so on.

Transport layer: Provides data transfer between two computers in a network connection to the upper application layer. Contains the TCP protocol, UDP protocol.

Network layer: Used to process packets that flow over the network. This layer specifies what path (the so-called transmission route) arrives at the opponent's computer and transmits the packet to the other.

Link layer: The hardware part used to process the network.

An example of TCP/IP communication with HTTP protocol is the transmission process:

First, the client on the sending side sends an HTTP request to see a Web page in the Application layer (HTTP protocol).

Then, for the convenience of transmission, the data received from the Application layer (the HTTP request message) is segmented at the Transport Layer (TCP protocol) and forwarded to the network layer by marking the serial number and the port number on each message.

At the network layer (IP protocol), increase the MAC address as the destination of the communication and then forward to the link layer.

The server at the receiving end receives data at the link layer, which is sent sequentially to the upper layer, to the application tier. When transferred to the application tier, it is true that HTTP requests sent by the client are actually received.

The purpose of the IP protocol is to send various packets to each other. The two important conditions are IP address and MAC address.

The TCP protocol splits the data to make it easier to transfer big data, and the TCP protocol verifies that the data is ultimately delivered to the other party (three handshake).

The DNS service provides parsing services between domain names and IP addresses.

A URI is a positional identifier for a resource represented by a protocol scheme, identifying an Internet resource with a string, and a URL representing the location of the resource (where the Internet is located). The visible URL is a subset of the URI.

Schematic HTTP NOTE Summary