User guide

1: Overview
DC 900-1303C 17
1.2 Freeway Client-Server Environment
Freeway acts as a gateway that connects a client on a local-area network to a wide-area
network. Through Freeway, a client application can exchange data with a remote data
link application. Your client application must interact with the Freeway server and its
resident ICPs before exchanging data with the remote data link application.
One of the major Freeway components is the message multiplexor (MsgMux) that
manages the data traffic between the LAN and the WAN environments. The client
application typically interacts with the Freeway MsgMux through a TCP/IP BSD-style
socket interface (or a shared-memory interface if it is a server-resident application
(SRA)). The ICPs interact with the MsgMux through the shared-memory interface of
the industry-standard bus to exchange WAN data.
This document is intended to support clients that use a TCP/IP BSD-style socket inter-
face only. Server-resident applications that use a shared-memory interface are beyond
the scope of this document.
Figure 1–2 shows a Freeway connected to locally attached clients by a TCP/IP network
across an Ethernet LAN interface. Note the following about the clients in this figure:
• Both clients do not use the DLI.
• Client1 uses the client TSI layer. If this is the case with your client applications,
you will only need to reference this document to determine packet header formats
and field values. Your primary reference for TSI information will be the Freeway
Transport Subsystem Interface Reference Guide.
• Client2 does not use the client TSI layer. If this is the case with your client appli-
cations, you will need to use this document as your primary development tool.