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Linking VAX computers via IBM-based interface.

When the financial information company Quotran became part of Citicorp, the company wanted to take advantage of the bank's Global Report and electronically deliver the information to the stock brokers who make up Quotron's client base.

But there was one hurdle: the two companies had different computer environments. Citicorp used VAX computers from Digital Equipment Corp. to collect and process data for Global Report, which delivers financial news, fixed income reports and foreign exchange rates. Quotron's network communicated with 100,000 custom terminals worldwide using an IBM-based interface know as 3270 binary synchronous, or BSC for short.

"While Quotron wanted to provide Global Report to our clients, we asked ourselves 'How can we get that information from the bank to our clients,'" said Alfred DiMola, director of systems for Quotron's Global Treasury Services (GTS). "The only way Quotron had to communicate over its existing network with its installed terminals was through an IBM-based interface that was incompatible with the bank's VAX computer."

The challenge faced by Quotron was not unusual. In the 1960s and '70s, many organizations, particularly financial companies, built networks based on IBM host computers and terminals. The way the computer communicated with IBM's 3270 terminals was via the BSC communications protocol, the predecessor to today's SNA and SDLC networking interfaces.

In the years since 3270 BSC communications networks were established, however, organizations have brought in non-IBM computer equipment, either through upgrades or mergers of companies with different systems. Rather than make a costly, time-consuming, and difficult switch to a new communications protocol to support the new hardware, the companies retained BSC as the network communications standard.

That was the solution Citicorp and Quotron implemented. They retained their VAX computers for processing and collecting the data for Global Report while also keeping the 3270 BSC as the communications interface to the network.

The information for Global Report, which is now a service of Quotron, flows into the VAX computers at Quotron's information center in Parsippany, N.J.

GTS collects the information for Global Report through satellite dishes, telecommunications lines, Ethernet networks, and high-speed T1 communication lines.

"We gather all this information from various sources and process it on the VAXes to make it useful for our clients," DiMola said. "We combine the data into consistent structures, graphs and formats so it can be dealt with on the same level by everyone."

Quotron faced two challenges in determining how to communicate the VAX information over the BSC interface.

"First, bisynchronous communications is tremendously compute-intensive, requiring extensive protocol processing and data buffering," he said.

Second, DiMola said, communications processing must be able to check for and respond to a wide variety of error conditions if incorrect information is sent or received. Every time a message is completed between a host computer and a terminal, the two systems exchange further information to check that the message has been received correctly.

Quotron faced a significant programming task to write the BSC interface software to cover every possible communications error contingency, DiMola said.

"We solved both problems by offloading communications from the VAX computer onto a front-end processor and buying the BSC interface software off-the-shelf," he said.

The board and BSC software came from Simpact Associates, Inc., a San Diego-based company that specializes in data communications for financial computing applications. The board's microprocessor accommodates all the complex BSC protocol processing and buffering of messages.

These types of communications boards are also known as intelligent communications processors (ICPs) because, like a computer, they can be programmed to handle specific tasks.

DiMola said the programmability of the board provides Quotron with the flexibility to handle another communications problem.

While 3270 BSC is a standard interface, Quotron had customized its version to meet specific requirements.

"We programmed the board to do the specific function of omitting the device number and control unit required by standard BSC," DiMola said.

"Because the board was able to handle our custom BSC network requirements, we were able to avoid extensive rewriting of code on the application side."

By processing its 3270 BSC communications on a front-end board rather than on the VAX computers, Quotron a accomplished several goals. The company was able to leverage its existing computing investments: both the information resource (Global Report) residing on a VAX computer and the IBM-based communications interface. In addition, off-loading communications from the VAX reduced the possible processing overload to Quotron's computers.

"Front-end data communications offered an efficient solution for allowing us to continue with our established communications network yet improve our services by incorporating hardware from a different vendor." DiMola said.
COPYRIGHT 1991 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1991 Gale, Cengage Learning. All rights reserved.

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Title Annotation:connectivity
Publication:Communications News
Date:Aug 1, 1991
Words:759
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