Beginner Introduction to OSI Model and HTTP Protocol
The Open System Interconnection (OSI), Standardize the way computer systems send information to each other, have to follow a protocol with standardize system which grab into play OSI model to address information communication protocol. which is commonly used to focus on how information network function to connect each other.
Layers
Communication within computer systems ought to be progress on flow of data between them. Those systems have some computer programs which can communicate them as to send and receive data properly.
Knew that, always having challenges for communicate information one point to another point thus to solve specific type of problems, authorities come up with a solution as architecture of the model in layers which was minimized to seven layers. Different problems are solved by numerous protocols that have evolved with time. Let’s discuss all the seven layers one by one in the next section.
Application Layer
This layer comply for user to access internet, simply any of the client can access the internet through this layer. Data exposure is happen in this layer.
Such Remote access Databases, Remote transfers . These data transform through some protocols, which are enable through this application layers
such as protocols are:
HTTP — Hyper Text Transfer Protocol
FTP — File Transfer Protocol
SMTP — Simple Mail Transfer Protocol
DNS — Domain Name System
Presentation Layer
This layer is concerned with the semantics and syntax of the information exchanged between the systems.
below are the key procedures covering from this layer:
- Encryption/Decryption of data: In simple words, encryption is the method of transforming the original message and sending it so as to ensure the privacy of data being transmitted. The decryption reverses the original process to transform the message back to its original form.
- Compression: It is the reducing the number of bits contained in the information to be sent. This plays vital role in the transmission of information in form of audio, video, images, etc.
- Translation: The information exchanged between two systems happens in form of bit streams (many bits at once), but since different computers use different encoding systems( ASCII, Unicode or may be some other), it is the responsibility of this layer to ensure interoperability between these different encoding methods.
Session Layer
This layer establishes, maintains, and terminates sessions. A session is a mutually agreed upon connection that is established between two network applications.
Following are the key concepts of this layer:
Dialog Control: It allows the communication between two processes to take place in half duplex (one way at a time) or in full duplex mode ( both ways at a time)
Synchronization : To ensure data packets are transmitted correct order this layer implementing check points with in the transformation tunnel. This mechanism helpful to troubleshoot the errors when finally recognized all data packets are not received/having error.
Transport Layer
This layer applicable and ensuring Process to Process data transformation.
Accept the data from the session layer, divide into small chunks while ensuring data order sending to network layer as small chunks of packets.
Following are the key functionalities of this layer:
Flow Control: With Data link layer implements flow control mechanism.
Error Control: With the help of Data link layer, transport layer on sender side ensures that the message arrives correctly on the transport layer on the other side.
Network Layer
This layer is responsible for ensuring the source to destination delivery of a packet. This layer applicable for if systems are connected different networks are going to share data.
Some of the responsibilities of the network layer are:
Logical Addressing: This layer add in its headers, the logical addresses of the sender and the receiver before passing down to Data Link Layer.
Routing: It is the mechanism of identifying suitable routes for sending data packets in the fastest possible and efficient way.
Data Link Layer
This layer makes the physical layer appear error-free to the upper layer. It provides end-to-end validity of the data being transmitted.
Some key functionalities are:
Flow Control: It ensures the data traffic between receiver to sender as with the help from Transport layer
Error control: Provides mechanism to detect and retransmit damaged or lost frames. This is done by adding a trailer at the end of the frame.
Access Control: When two or more devices are connected to the same link, the This layer determines which device will have control over the link at any given time.
Logical Link Control (LLC): Mechanism for identifying data from the physical layer and transmit the data to higher level layer by identifying the Internet Protocol (IP).
Physical Layer
Lowest layer of the OSI Model, with capable of physically deal with systems as connecting devices through certain network protocols. And coordinate between all the functions required to carry a bit stream over a physical medium. expose procedures that physical devices and interfaces should follow and progress each other.
That’s all about OSI layer. Now let’s move into HTTP protocol.
What is HTTP Protocol
It is a client-server protocol means requests are initiated by the recipient(i.e Web browser). Communication between them is done by HTTP Requests and HTTP Responses. It gives a way to interact with web resources(eg. HTML files) by sending hypertext messages between clients and servers. HTTP clients use TCP/IP connections to communicate with the servers.
How does HTTP protocol works
Client-Server communication is done by request and response:
- Browser sends an HTTP request to the server.
- A web server receives the request.
- The server runs an application to process the request.
- The server returns an output(HTTP response) to the browser.
- Browser receives HTTP response.
- And finally browser interpret and render the HTTP response.
Hope you all understand the OSI model and HTTP.
Happy Learning.