Field Installation of a Distributed Database Application—Concept vs. Reality
E. L. Evans, M. R. Berry, M. C. Goings · SPE Computer Applications · 1993
Summary A PC-based equipment-failure reporting system was designed as a distributed database over a wide area network (WAN). Speed-related communication problems were encountered, necessitating program redesign. In the original design, data for local failures were to reside in several local field offices. Division-level reporting was to be accomplished by concatenating the field offices' databases over the network. Validation information was to reside in several small databases on the division fileserver. These data were to be accessed by the field offices as a remote link. The program executables were to reside on yet another fileserver belonging to the service organization that maintained the program code. Both the field and division offices were to access the program code as a remote link. It soon became apparent that the communications link between the division and field offices was too slow for both division failure reporting and field failure validation. Although not encountered, a break anywhere in the chain of communications would disable the application in all locations. These problems were overcome by actually running from local copies of the files but continuing to treat the various files as if they were in remote locations. Maintenance routines were created to update the local copies. This paper discusses the network and communications facilities in place, the original design, the performance encountered, the design changes, and current performance. A brief discussion of possible future modifications is included.