4.3.6 Legacy Applications and External Communications
Several legacy ITS applications will be integrated with CHART II: SCAN, EORS, Econolite Aries signal control system, and WSI Weather for Windows via their database. figure 4-10 expands on the architecture illustration in figure 4-5. figure 4-11 illustrates a topological view of the legacy interface architecture. As an object wrapper, each protocol translator may operate on legacy data, control stream, and/or communication protocol.
As figure 4-11 illustrates, the mechanics of information transfer between the legacy application and the CHART II user will be handled by a processing utility—the object wrapper (middleware in contemporary terms)—that performs the data exchange. The protocol translator provides an IDL interface between CHART II and the legacy application acting as an application program interface translator.
Figure 4-10. Protocol Translators CHART II Software Architecture Components
CSC/PBFI Advantage: Legacy applications are integrated into CHART II using protocol translators
The legacy applications just discussed are shown on the right side of figure 4-11. On the left side are cooperating external ITS organizations. CHART II and these external organizations share incident information that may affect travel on major routes throughout the region. For external communications message and communications protocol translation must be performed rather than the process translation done for legacy applications. Message translation is relatively straightforward. Communications protocol translation is a bit more complex, but the translator would have the same object-oriented architecture illustrated by figure 4-10.
Figure 4-11. A CHART II Legacy System Interface Architecture Topological View
CSC/PBFI Advantage: Information transfer between legacy applications and the CHART II consumer will be handled by a processing utility that performs the data exchange