By Amy Gorin
Many developers of network applications have begun to turn to the Unix operating system over DOS, convinced that it provides a more flexible environment for development and expansion.
At the Kennedy Space Center near Orlando, Fla., a development team at NASA's Design Engineering Directorate is designing a voice-conferencing system that will be used during the next space shuttle mission to link 5,600 NASA employees in 500 separate conference channels. Each channel will be dedicated to a different facet of the launch, such as fueling, hydraulics, navigation and safety.
The team, NASA's Operational Intercom System--Digital (OISD), is also
developing a Unix-based network application
that will allow technicians to monitor and troubleshoot the conferencing network.
OISD is developing the Unix application using 80386-based machines from Intel Corp., Compaq Computer Corp. and NEC Information Systems Inc. running AT&T's Unix System V version 3.1. The PCs running AT&T's Unix also run X Windows, a user interface and windowing software package available from AT&T. To run X Windows, the machines are equipped with very high-resolution (1,600 by 1,200 pixels) monitors and with Bullet Express graphics cards from Bell Technologies of Fremont, Calif.
The OISD developers' machines are networked to each other via Ethernet using Excelan and Micom Ethernet cards and software. The local Ethernet also links to a broadband network, which connects local work groups in the Industrial Area, a cluster of buildings for support and engineering departments at the space center. This lets the OISD group share files and E-mail with over 600 users at the center. NASA is expanding that network, which uses TCP/ IP communications protocols, to serve the 100-square-mile space center.
The TCP/IP network will also be used to help run the voice-conferencing system itself using the OISD application.
Users on the voice-conferencing network will use consoles, which consist of a headset and a telephone control panel, to link to a centralized 68020-based dedicated switching system. The switching system will be connected to the space center's broadband TCP/IP-based wide area netwcrk.
In monitoring the voice-conferencing network, OISD's troubleshooting technicians will use '386-based PCs that are also linked to the space center network and equipped with Unix and X Windows.
Real-time troubleshooting of the voice conferencing network requires that OISD technicians be able to access the status of each user's console at the time a problem occurs to see what channels the user was accessing, and to determine the settings of volume and control switches. If a NASA launch engineer were to have trouble with a conference call, for example, the technicians would have to check the engineer's console settings to help them diagnose the nature of the problem.
Designers of the troubleshooting system "wanted an easy-to-use, intuitive interface, as well as an interface that someone could sit in front of for eight hours and not fall asleep," according to Phil Tharp, software project leader for OISD.
The technicans' PCs provide such an in terface, using a virtual-control panel pro gram called DataViews, by VI Corp. of Amherst, Mass.
Using the Unix/X Windows/DataViews package, the OISD system can simulate a user's console, displaying a picture of the knobs and dials exactly as they would appear to someone looking at the control panel -- complete with the current settings of the controls.
A technician can instruct his or her PC to show the console for any conference participant. If the technician cannot discover a solution by inspection, he or she can then access more complex data.
In either case, the troubleshooting can be done remotely, without the need for a visit to a user who may be several miles away.
According to Mr. Tharp, his team wouldn't even have tried to develop this kind of an application under DOS. Because DOS is not a multitasking operating system, he said, a developer who wants to use DOS in a networked application must "re-invent" pieces of the operating system, such as multiple-program file access and memory allocation, and communications between programs, which would exist in a multitasking system.
"Over the years," Mr. Tharp said, "people have borrowed things from Unix and implemented DOS versions. Why not just use the real thing?"
In addition, the group is now exploring using Al (artificial intelligence) to aid in diagnostics and help automate the trouble shooting process. "Since we're running Unix, which is a nice standard system," Mr. Tharp said, "we can get all kinds of AI-development support."
The use of a non-proprietary, multivendor operating system will also allow NASA to upgrade without fear of incompatibility. According to Mr. Tharp, "What people want is a modularly upgradable system, which drives you to using standards." Otherwise, he said "you keep changing the look of your applications."
NASA as a whole also recognizes the need for standardization to enhance user friendliness as well as connectivity. According to Mr. Tharp, the choice of a TCP/IP standard was driven by this need, and NASA will embrace the as-yet-undetermined government standard version of Unix, called Posix, when it becomes available, in an attempt to minimize the need for users and programmers to relearn variations in operating systems.
That relearning is, Mr. Tharp said, the only significant advantage to OS/2, which uses a DOS-style user interface. "When I try to get non-technical users to use Unix," he said, "they get real upset if anything is different from DOS."
OS/2's other advantage, Mr. Tharp said, is that it "has IBM and Microsoft, and their financial/political backing, behind it."
While NASA turned to Unix (rather than waiting for OS/2) to suit its somewhat esoteric development needs, Banyan Systems Inc., developer of the VINES net working system, chose Unix for more mundane applications: a network development and operating platform.
The company, based in Westboro, Mass., rejected DOS, according to Dave Williams, Banyan's director of product planning, because it is single-threaded and single-tasking. The way in which DOS handles access, allocation and sharing of resources such as memory and disk space make it unsuitable for multiuser and network tasks. "DOS was never designed to support network services. It was designed to be a single-user operating system," Mr. Williams said.
Other network manufacturers, he said, have embraced different strategies to over come DOS's problems: "3Com modified DOS [to overcome its multiuser problems], and Novell wrote its own kernel [a separate operating system]."
Banyan's solution, he said, was to "choose a mature kernel and put its services on top of it." According to Mr. Williams, Banyan chose Unix as the server platorm for VlNES because it is "the most open, most understood multitasking environment in the market today."
NASA's Mr. Tharp put it a bit more succinctly. As a development environment, DOS is completely inadequate, he said. [Actually he said "DOS just sucks," but my editor kinda freaked out on that one. They weren't too thrilled about unix or internet stories in general ...]
VINES users do run DOS programs, however, and are supposed to be shielded from the Unix network environment by a DOS "redirector," a background-resident program that will route a command either to the network or to DOS on the user's machine.
Some end users have other ideas. According to Mr. Williams, several sites are adding their own applications to their Banyan networks. Installations find this option attractive, he said, because the openness of Unix allows users to add their programs to the LAN environment without learning a proprietary operating system.
Some software vendors are looking to use Unix as a platform for new networking applications as well.
Applix Inc., also of Westboro, produces Alis, an integrated office-automation pack age designed to complement existing net works. Alis is compatible with Unix, VMS and DOS, and works with 3Com and Micom networks as well as Banyan's VINES. The Alis server software, however, is Unix- based.
According to Tony Goschalk, director of marketing for Applix, the company
"wanted to produce an office system that was vendor-independent. The need
for that level of' functionality precluded doing (the software] in DOS."
As for OS/2, "the market surrounding OS/2 and its applications," Mr. Goschalk said "is conditioning people to expect a level of utility and function it cannot yet deliver." Mr. Goschalk believes Unix and OS/2 may attract different classes of user, but also said he thinks those attitudes may be naive.
NASA's Mr. Tharp is certainly of the former, perhaps more impatient, class. Unix, he said, is a "real operating system available to take full advantage of the power of the '386 now."