Winsock and the OSI Model

In the International Organization for Standardization Open Systems Interconnection (ISO/OSI) model, Winsock operates at the session layer interface to the transport layer. Winsock is an interface between applications and the transport protocol and works as a conduit for data I/O. The following illustration shows Winsock in relation to other Windows CE communication protocols within the context of the ISO/OSI model.

Winsock simplifies application development in the upper ISO/OSI layers by handling the details of network data exchange at the lower layers. Winsock provides a programmable interface between the upper layers, 5-7, and the lower layers, 1-4. Winsock applications reside in the upper, application, presentation, and session layers. Winsock application data is packaged and transmitted over a network by the lower, transport, network, data-link, and physical layers.

TCP/IP and IrDA are lower layer protocols used by Winsock. Specifically, TCP fits into the transport layer and IP fits into the network layer.

Note Winsock provides the only way for an application to access the TCP/IP or IrDA protocols on a Windows CE–based device.