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Unix Integration

Connecting Wang VS and Unix systems

From "Special Report",  Access to Wang, June 1998
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Since the first part of this decade, Wang Laboratories and Wang VS users have each pursued paths of coexistence and migration with other types of systems. Beginning the with their first alliances with Banyon and IBM, Wang charted a strategy intended to guide their existing customers toward other systems as their needs required - first to Local Area Networks (LANs), then to the AS/400, and finally to Unix systems offered by IBM and Hewlett-Packard. The impetus for this seeming abandonment of the VS by Wang was a realistic assessment of the market and a desire to be a part of their customer's successes. The user community examined the many choices they were offered and some converted to other systems; the large number of VS systems that are still in production is a testimonial to the performance and reliability of the VS architecture.

Of all of the possible options for migration or coexistence, Unix systems have been the most successful. Unix vendors provided high-performance, low-cost systems and the ability to run a broad selection of off-the-shelf software. If you're considering changes to your applications, you've undoubtedly been wondering whether to merge your VS systems and users into a Unix environment and retaining the VS for migration or other purposes. Some of the reasons you might consider running a Unix/VS shop include:

Once you have decided that you need access to both environment, there are a number of issues to consider - and a number of ways to deal with them. We'll assume here that you don't want to create your own connection software and cover some products that can be applied without program development.

Connection models

There are two main methods for connecting VS systems (and users) to Unix systems: through asynchronous connections and via some sort of network connection. Examples of asynchronous connections include ports intended for Wang's 2110 asynchronous terminal and general asynchronous communications ports (DLCs) found on older VS systems. Options for network connections include two products that use the TCP/IP protocol that is native to Unix systems and gateway products such as Lightspeed NVS and Wang VS/LAN Connection. Each of these choices has advantages and disadvantages, so it would be difficult to recommend an approach without a careful study of the requirements.

The best-known asynchronous connection to the VS is the 2110 terminal specification, which allows a standard terminal to access a VS system. A typical configuration for 2110 workstation setup is shown in Figure 1, below. 2110 terminals resemble standard VT-100 terminals in features and protocol. Connections are made using standard serial connections (e.g. RS-232) and standard cables, modems, and other devices. The speed is limited to about 19,200 characters per second, but this is generally adequate for VS applications.

Network connection approaches provide a link between an existing LAN and the VS. TCP/IP products available from Wang and Sentinel Systems connect the VS to a network that uses the uses the TCP/IP protocol (see Figure 2). In addition, both offer Wang versions of two industry-standard connection services: Telnet, which supports terminal access to a system; and FTP (File Transfer Protocol), a file transfer and directory access system. Both services use the familiar host/terminal metaphor, where a "terminal" locates a "host" and "logs on" to that system, providing a user ID and password in the process.

Gateway connection approaches such as Lightspeed NVS (Figure 3) connect users of a LAN to the VS through a intermediate system "gateway" (typically a specially-configured PC) - one that is connected both to the network and to the VS using a Wang Local Office Connection (WLOC, a.k.a. the "928" connection) card. The gateway can be used to provide VS workstation services to with multiple PC users that are connected to the same network.up to seven other VS workstations. Like the 2110 solution mentioned above, connections to the Unix system must be provided by other means - typically, terminal services using the Telnet protocol.

Providing terminals to both systems: asynchronous terminals

If your users need access to Wang and Unix systems simultaneously but do not need many other features, using terminal emulation might be a good choice. This connection model provides the end user with access to both systems, which "integrates" the systems only in the sense of providing an easy way of moving between them. Since most workstations are now desktop systems, it is relatively easy to switch screens to access one system or the other as needed.

Setting up users with 2110 terminal connections is relatively easy: connections are made with serial communications, using industry-standard cables, connectors, and modems. Workstations can be simple serial terminals ("dumb terminals"), but are more often desktop systems using terminal emulation software. You can use specialized 2110 emulation software (available from several sources listed below) or use standard VT-100 terminal emulation software. The specialized 2110 emulation programs offer support for keyboard mapping, file transfer, and printer support that is tailored to the needs of Wang users. If a standard emulation program is used, however, the same program might be used for access to the Unix system as well.

If the number of terminal connections you require is small, 2110 emulation might be the best choice. Any type of serial connection may be used, including direct cable, modems, or terminal servers (devices that convert network sessions into serial connections).

Network interconnection using TCP/IP

Connecting single terminals between Unix and VS systems can be helpful in many cases, but network connections between the systems add file transfer and standard terminal services to the capabilities. If the connection between the systems uses the TCP/IP protocol, you can also use a variety of standard tools and protocols and even provide public access to your VS system if you wish. Both Wang and Sentinel TCP/IP products provide standard host services that can be used with a variety of client products. These include the following:

Each of the two TCP/IP products has very different hardware and software requirements. Wang's product is built on their WSN (Wang Systems Networking) products and requires the base network software and interconnection hardware before the TCP/IP product can be used. Sentinel's product uses a dedicated PC system as a gateway between the TCP/IP network and the VS system.

While TCP/IP connections to the VS are flexible, the setup cost is high. Wang's TCP/IP products require Wang Systems Network (WSN) core components in addition to specific TCP/IP software and a special controller, so it may be too costly a solution unless you already have a substantial involvement with WSN components. Sentinel's TCP/IP solution requires a dedicated personal computer with both network and Wang terminal emulation cards installed. Naturally, the cost of LAN cabling must also be considered if you do not already have it in place.

Integration with gateway systems

Gateway products from Wang and Lightspeed Software's products use a PC much like Sentinel's TCP/IP product. Each gateway PC must have a network interface card (NIC) and a Wang Local Office Connection (WLOC) board as well. Each of these gateways can provide access for eight or more workstations, depending on the product version. Software is also required at the PC end to connect with the VS and provide printer support through a local or network printer. Unlike the two TCP/IP products, either product Lightspeed can use a variety of network protocols.

Conclusion

The products and technologies required to merge Unix and VS operations are diverse and must be evaluated against your needs. The capabilities of each of the four options discussed above are summarized in Figure 4.

The products and methods mentioned here are by no means exhaustive. Since several manufacturers provide the means to create custom communications applications that work with the VS, it is possible to create other communication systems to meet specialized needs. Some of these include:

VS/Unix integration can provide your organization with additional capacity, the ability to use standard network client software, and public access to your information. The way you use these capabilities depends on the future you see for the Wang systems in your shop - a short-term migration strategy, long-term access to core business information, or something between.

References

Sentinel Technologies, Inc.
2550 Warrenville Road
Downers Grove, Illinois 60515
630-769-4300
http://www.sentinel.com/

Lightspeed Software
1800 19th Street
Bakersfield, CA 93301

805-324-4291
sales@lightspeedsoftware.com
http://www.macsoft.com/

Wang Laboratories Inc.
600 Technology Park Drive
Billerica, MA, 01821-4130

978-967-5000
http://www.wang.com/service/


Figure 1: 2110 Terminal Connection Model

[Diagram of Wang 2110 Workstation Connections]

Figure 2: TCP/IP Connection Model

[Diagram of TCP/IP Connections to the VS]

Figure 3: Gateway Connection Model

[Diagram of Lightspeed NVS]

Figure 4: Comparison of Services

Service Wang TCP/IP Sentinel TCP/IP 2110 Terminal Emulation Lightspeed NVS
Inbound Terminal Services X X X X
Outbound Terminal Services X X    
Printing     X 1 X
Electronic Mail Interchange X 2     X 3
Document Conversion     X 4  

Notes:

1. Services available when required VS software is also present.

2. Works only between Wang Office and specific LAN electronic mail packages.

3. Requires optional software.

4. Requires optional software.


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Copyright 1998 Dennis S. Barnes
Reprints of this article are permitted without notification if the source of the information is clearly identified