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