1. Computer network structure hierarchy
2.TCP / IP communication transmission stream
When network communication using TCP / IP protocol family, it will be communicated with each other through a hierarchical order. Go down from the transmitting side application layer, the link layer from the receiving end to go up. as follows:
3.TCP / IP communication transmission stream
- First, as the sender of the client application layer (HTTP protocol) want to send a HTTP request to a Web page.
- Next, in order to facilitate transport, the transport layer (TCP protocol) received from the data at the application layer (HTTP request message) is divided, and marked with the tag ID and the port number forwarded to the network layer in each packet.
- Forwarded to the link layer is the network layer (IP protocol), increase as the communication destination MAC address. Thus, the communication request sent to the network to complete the preparation.
- Receiving end server receiving the data link layer, sequentially transmitted to the upper layer until the application layer. When the transmission to the application layer, can be considered actually received by the client sent from the HTTP request.
as the picture shows:
4.HTTP request
HTTP protocol (HyperText Transfer Protocol, Hypertext Transfer Protocol) is a protocol used to transfer hypertext transfer from the WWW server to the local browser. It can make the browser more efficient, so that network traffic is reduced. Not only does it ensure that the computer correctly and quickly transfer hypertext document, the document also determines which part of the transmission, and which first part of the show (such as text prior to graphics) and so on.
HTTP is an application layer communication protocol between the client browser and the Web server, or other program. On the Web server on the Internet are stored hypertext information, client needs hypertext transfer protocol HTTP information to be accessed through. HTTP contains the commands and transmit information, not only for Web access can also be used for communication between other Internet / Intranet applications, enabling a variety of applications hypermedia access to resources integration.
We called the URL (Uniform Resource Locator, uniform resource locator) in the website address in the address bar of the browser input. Like every household has a house the same address, each page also has an Internet address. When you enter a URL in the browser address box or click a hyperlink, URL to determine the address to browse. Browser via Hypertext Transfer Protocol (HTTP), the Web site on the server page code extracted and translated into beautiful web.
