Installation guide

18 DC 900-1325I
Freeway Server-Resident Application (SRA) Programmer Guide
1.2.1 Basic SRA Configuration
When the client application resides within the Freeway environment instead of the cli-
ent system, the application is called a server-resident application or SRA. In the Freeway
environment, the DLI and TSI layers still exist. The SRA interfaces with these layer in
the same manner as on the client system. The difference is that the TCP socket interface
between the client and server is replaced by the local loopback IP address (127.0.0.1 or
localhost). Figure 1–2 shows the basic SRA configuration.
The loopback test programs provided by Protogate with each protocol package is a
good example of a basic SRA. The loopback test programs may be run on the client sys-
tem or directly on the Freeway server by logging into the Freeway menus and running
the programs from the FreeBSD shell.
From the perspective of the application programmer, the DLI and TSI code are the same
regardless of whether the application resides on a remote computer or within the
Freeway server. The information in the Freeway Data Link Interface Reference Guide and
the Freeway Transport Subsystem Interface Reference Guide applies to the development
of both client applications and Freeway server-resident applications.
1.2.2 Protocol Converter Configuration
Another example design is to use an SRA as a protocol converter. In this example, the
SRA reads data packets from one protocol on ICP0 and sends the packets out on ICP1
using a different protocol. Figure 1–3 shows this configuration.
Using an SRA in this
manner essentially turns the Freeway server into a standalone protocol converter box.
In addition, the SRA could also make a DLI/TSI connection to an ICP board on another
Freeway server somewhere else on the network. In this configuration, the SRA would
read packets from a local ICP and send them across the network to an ICP board on the
other Freeway server using the same or different protocol.