Session Layer
The session layer establishes, manages, and terminates communication
sessions between presentation layer entities. Communication sessions
consist of service requests and service responses that occur between
applications located in different network devices. These requests and
responses are coordinated by protocols implemented at the session layer.
Some examples of session-layer implementations include Zone Information Protocol
(ZIP), the AppleTalk protocol that coordinates the name binding process; and
Session Control Protocol (SCP), the DECnet Phase IV session-layer protocol.
Also provides dialog control between devices or nodes. Coordinates and
organizes communications between system by offering three different modes:
simplex, half-duplex, and full-duplex. The layer basically keeps different
applications' data separate from other applications' data.
Session Layer Protocols and Interfaces
NFS
-Network File System, developed by Sun Microsystems and used with TCP/IP
and Unix workstations to allow transparent access to remote resources.
SQL
-Developed by IBM to provide users with a simpler way to define their
information requirements on both local and remote systems.
RPC
-A broad client / server redirection tool used for disparate service
environment. Its procedures are created on clients and performed on
servers.
X Window
-Widely used by intelligent terminals for communications with remote Unix
computers, allowing them to operate as though they were locally attached
monitors.
AppleTalk Session Protocol
-A client / server mechanism which establishes and maintains sessions
between AppleTalk client and server machines.
Digital Network Architecture Session Control Protocol
-A DECnet session layer protocol.
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