In understanding the HTTP protocol family components, so let’s take a look from his family.
Most of the networks we use, including the Internet, operate on top of our TCP/IP family of protocols. HTTP is a subset of it.
TCP/IP protocol
A protocol is a rule that computer and network devices must communicate in the same way.
For example, rules on how to detect a communication target, which side initiates the communication first, which language is used for communication, and how to end the communication need to be determined in advance. Communication between different hardware, operating systems, all of this requires a rule. This rule is called a protocol.
There are all sorts of things in agreements. From cable specifications to the method of selecting IP addresses, the method of finding remote users, the order in which the two parties establish communication, and the Web page display of the steps to be processed, and so on.
A collection of protocols associated with the Internet like this is collectively called TCP/IP. It is also said that TCP/IP refers to TCP and IP. Another view is that TCP/ IP is the general name of the protocol family used in IP protocol communication.
TCP/IP layer and corresponding network protocol
An important aspect of the TCP/IP protocol family is layering. The TCP/IP protocol family is divided into four layers: application layer, transport layer, network layer, and data link layer.
The advantage of having TCP/IP layered is. For example, if the Internet is governed by only one protocol, when a design change is needed somewhere, all parts must be replaced altogether. After layering, you only need to replace the changing layers. Once the interfaces between the layers are laid out, the internal design of each layer is free to change.
It is worth mentioning that the design becomes relatively simple after the layering. Applications at the application level can just think about the tasks assigned to them, without having to figure out where on earth they are, what their transmission routes are, and whether they can ensure delivery.
Application layer: Generally writing applications determines the application services provided to users. The application layer can communicate with the transport layer through system calls. For example, FTP, DNS, and HTTP.
Transport layer: The transport layer provides the transfer function between two computers in a network connection to the application layer through system calls. At the transport layer there are two different protocols, TCP and UDP.
Network layer: Used to deal with packets of data flowing over the network. Packets are the smallest unit of data transmitted over the network. This layer defines the path through which the data reaches and is transmitted to each other’s computers.
Link layer: The hardware part that connects to the network, including the control operating system, hardware device drivers, NICS, and optical fibers. Hardware categories are within the scope of the link layer.