applied solutions: Compression Speeds Data Deliveries to Food City Stores
Before your chain supermarket can sell you your weekly groceries it has to know what to charge you. Sale prices can change daily and they have to be uniform in every store.
Every night K-VA-T Food Stores Inc., based in Abingdon, Va., transfers data files from its AS/400 Model 510 to its chain of 80 Food City Supermarkets in Kentucky, Virginia and Tennessee. The files contain information the stores will need in order to do business the following day: information on price changes, future price and product changes, and the labels and signs that the stores will have to print.
According to Patrick Shrader, senior systems analyst, a file sent to a single store typically will contain about 16 MB of uncompressed data, and all 80 stores have to receive them before they open in the morning. Unless the data is compressed, the nightly transmission would take too long.
In addition, files have to be sent to Unix-based NCR processors at the stores, chosen for their small footprint, and their ability to communicate with the stores' point-of-sale computers.
Until three years ago, the out-going files, generated by a legacy RPG program on the AS/400, would be sent over a LAN to a Unix processor at the Abingdon headquarters, compressed one at a time using the Unix compress command, then sent via the Hughes satellite network to the stores.
"We created the files on the AS/400, and transferred them to the Unix machine here. Then, when all the files were compressed, an operator had to manually hit the send button on the Unix machine. That took a lot of time. Somebody had to pay attention to it. If that person got tied up or distracted, the files might not get out."
To save time, Shrader wanted to find a data compression utility program for the AS/400 that would allow it to communicate directly to the Unix processors in the stores without the intermediate Unix machine.
Shrader was familiar with the Miamisburg, Ohio-based Ascent Solutions PKZIP product for DOS, having used it during his high school and college days. "We wondered if there was a product like PKZIP for the AS/400," he says. "We found that Ascent Solutions had the same PKZIP utility available for both the AS/400 and Unix."
"It was the best product we found that would allow us to use the same algorithm on the AS/400 and the Unix machines at the store level," he continues. "As a result, the file transfer process is now completely automated. A single command at the AS/400 will create the files and the next thing you know they are at the store with no manual intervention."
By doing the compression at the AS/400 instead of the Unix machine, not only is the need for the presence of an operator eliminated, but the whole process runs from three to four hours faster.
"We start the transfer process about six in the evening and finish about three in the morning," Shrader says. "Previously, it would finish closer to seven. In that respect it's a tremendous saving. The data compression is also much better than the Unix algorithm--we're getting a compression ratio of nearly fifteen to one. But that's a relatively insignificant benefit for us. It's the time saving and the ease of being able to transmit directly from the AS/400 that's the big advantage."
According to Shrader, K-VA-T has found an additional use for PKZIP and is considering more. "We have created an internal messaging system," he says. "It's not full blown email, but it allows us to send PC documents out to the stores."
In this application, he says, a PC generates a word processing or spreadsheet printer file, prints it to a disk file, compresses the disk file using PKZIP on the PC, and transmits the file over the satellite network to the store. The store uncompresses the file using the Unix version of PKZIP and prints it.
"They get an exact copy of what the document looked like here," Shrader says, "but we don't have to print eighty copies, stuff them in envelopes and send them to the stores."
Essentially, it operates like an enterprise-wide fax. "We basically developed an enterprise fax forwarding system," he explains. "Since we already had the equipment at all the locations, it only took a few hours for a couple of programmers to do it. It's a huge time and labor savings. The stores can get the information they need in hours instead of days."
In the future, Shrader would like to put the PKZIP utility on additional machines at the store level. "We have about ten point-of-sale system PCs in the stores, running either DOS or SCO Unix. I'd like to put the PKZIP product on the point-of-sale systems to directly communicate certain information directly to them. Now I can go to the in-store processor--the NCR Unix machine. But I could go to the point-of-sale boxes as well using the same application," he says. "It's not a big issue, but it would make things even easier."