Technical issues can be perplexing! In this section we attempt to explain technical matters that have special interest in the WISL community.

Network Interface

Information systems sometimes require communication between different computers. This can be as simple as the communication required to share a printer amongst several PC workstations or it may involve sharing data amongst different types of computers(ie. computers running different operating systems) during an interactive process. In the latter case, common ground must be found as a basis for communication between the different machines. It is assumed that the computers would be connected on a network with a cable(often ethernet twisted pair or BNC) with a basic messaging protocol(often TCP/IP which is the protocol used on the internet). Computer communication protocol has the same connotation as the word used in a diplomatic context ie. the computers follow  "protocol", an expected message and response pattern, during communication.

Each computer is running its own version of the program that is expecting a given pattern of message/response from the other. Simple tasks such as request and acknowledgement of operational status are usually handled by the basic layer but more complex procedures such as file transfer often require additional layers of communication software(in the case of TCP/IP, file transfer is usually handled by a software layer known as FTP - File Transfer Protocol).

The LANPoint PRO computer from Intelligent Instruments Inc which runs on DOS offers two options for network communication. It supports NFS(Network File System) and ODBC(Open Data Base Connectivity) protocol. 

Since the DBMS that WISL uses in its server based applications(UniVerse) supports ODBC and all operating systems that WISL employs to run its server based applications(Windows NT, LINUX or UNIX) support NFS, it is the requirements of the specific application and the corresponding features of the two methods that determines which protocol is utilized. The essential difference between the two protocols is that ODBC provides for record level update over the network whereas NFS handles access and update only at the file level. Although NFS provides less functionality, it is less complex to implement and presents fewer opportunities for operational difficulties. WISL's process control applications do not require record level access and therefore NFS is utilized as the communication protocol between the LANPoint PRO and the server.