WebSocket protocol is typically located in the application layer, which is the seventh layer of the OSI model. WebSocket is a protocol that provides a full-duplex communication channel for web applications, enabling the establishment of a persistent connection between the server and client for real-time data transmission.
For example, in a real-time chat application, when using HTTP, the client must initiate a new HTTP request each time a user sends a message and wait for the server's response. This method is slower, and re-establishing the connection each time is required. In contrast, WebSocket establishes a persistent connection following the initial handshake, allowing bidirectional data transmission through this connection without re-establishing it, significantly improving communication efficiency and speed.
Additionally, although the WebSocket protocol resides in the application layer, it often works alongside transport layer protocols such as TCP to ensure reliable data transmission. Therefore, while primarily an application layer protocol, its implementation also relies on support from lower-layer protocols.