Application Layer in OSI model explained.
The 7th layer in the OSI model is the application layer. It interacts with the lower layer, which is the presentation layer. The user of the application layer is the software or application that implements the functionality. For example, if we talk about the web service. Then HTTP is an application layer protocol. HTTP works in a client-server model.
The web browser and web server are examples of the users of the Application layer. But in the case of HTTP. The OSI model is not followed thoroughly. There are no session and presentation layers below the HTTP.
If we want to understand the application layer, we need to understand the protocol examples. Below is a list of examples.
Application layer example protocols :
| Protocol | Description |
|---|---|
| XMPP | Extensible Messaging and Presence Protocol |
| VTP | Virtual Terminal Protocol |
| SSMS | Secure SMS Messaging Protocol |
| SNTP | Simple Network Time Protocol |
| SMP | Server Message Block |
| DeviceNet | automation industry protocol |
| COAP | Constrained Application Protocol |
| DDS | Data Distribution Service |
| eDonkey | classic filesharing protocol |
| FasTrack | Filesharing, known from KaZaa and more |
| HTTP | HyperText Transfer Protocol |
| H.323 | Packet-Based Multimedia Communications System |
| IRCP | Internet Relay Chat Protocol |
| LDAP | Lightweight Directory Access Protocol |
| MIME(S-MIME) | Multipurpose Internet Mail Extensions and Secure MIME |
| NIS | Network Information Service |
| RDP | Remote Desktop Protocol |
| RTP | Real-time Transport Protocol |
| SIP | Session Initiation Protocol |
| SSH | Secure Shell |