Introduction to Tandem X.25 Capabilities

Using TCP/IP and OSI over X25AM
X25AM Implementations
3–12 065307 Tandem Computers Incorporated
Railway Reservation
System Using TCP/IP
and OSI over X25AM
A railway reservation system combines LAN and WAN functions, by running TCP/IP
and OSI applications over X25AM (Figure 3-6). Transactions are initiated at terminals
connected to UNIX workstations over either an Ethernet LAN or a public data
network. The UNIX workstation routes seat-reservation transactions to the NonStop
system, and routes railway time-table queries to either another system on the LAN or
public data network . The railway reservation application uses Pathway, operating on
an SQL database. The application uses Tandem OSI products for connection to both
local-area and wide-area networks. For the local-area network, the OSI products run
over the Tandem LAN Access Method (TLAM); for the wide-area network, the OSI
products run over X25AM. There is one communications programming task on the
NonStop system: a front-end process using OSI/TS supports cooperative processing
between requesters on the UNIX workstations and database servers on the NonStop
system. The same application code works in both network environments (LAN and
WAN). (The fact that each OSI/TS process uses a different instance of TLAM or
X25AM represents an application designer’s choice, not a configuration restriction.
Multiple instances of OSI/TS can use the same I/O process, and one instance of
OSI/TS can use both X25AM and TLAM.)