transport layer interface (TCP/IP) (TLI)

The Transport Layer Interface or Transport Level Interface (TLI) is a protocol-independentprogramming interface( API) via which the application programs can access network services.

The functions of the Transport Layer Interface are adapted to the transport layer according to the International Standards Organization( ISO). It was first introduced with UnixSystem V Release 3.0 (SVID) and its specifications are defined by SVID. It is a transport mechanism for network interfaces with a preference for sockets.

The Transport Layer Interface (TLI) and the X/Open Transport Layer Interface(XTI) were used extensively until Unix 98, which preferred the programming interface over POSIX sockets. They are still supported by Unix System Release 4.0 (SVR4).