Hot Backup of a TE System

A large New England retailer of sporting goods upgraded their data collection system by installing Symbol Technologies 9060 hand held computers and Symbol's switch based RF network. The hand helds were connected by 802.11 radios to the company's warehouse management system running on an AS/400. The 9060's run a Telnet 5250 session to collect warehouse transactions and send them to the warehouse software.

The first installation of this system was halfway across the country, and our customer needed a way to continue to operate his warehouse if their WAN connection went down. This is a weakness of TE based systems-- if the host goes down, your data collection device becomes a battery powered brick.

Our Solution

The Symbol 9060 runs Windows CE.net 4.2 as an operating system. We installed Switchboard, our Data Collection Server, and wrote them a program in VB.NET that collected transactions when the WAN went down. Transactions are written to a local SQL Server database, and uploaded to the AS/400 when it comes back on line. We also allowed them to store data in the hand helds themselves, in case the RF network went down. With this system, warehouse operations can continue, even if the WAN or the RF network are down

The Pick Menu:

How it works

When the user's AS/400 TE session stops responding, they switch over to the VB program and begin collecting data. If the RF system is available, transactions are immediately posted to a SQL Server table, and later posted to the AS/400 when it becomes available.
If the RF system is down, the reader writes the data in Switchboard format to a text file that is stored on the 9060's and transferred to the Switchboard PC automatically when the RF network becomes back on line. These files are processed by the Batch Client and sent to Switchboard, and then to the SQL Server table.

As a further back up, the text file resides on a Secure Digital card, so in the unlikely event that a 9060 goes down with stored data, the SD card can be removed and the collected data recovered.

Switchboard, our data collection server software, manages all of the uploading, downloading, and communications between the database and the Symbol readers.

Of course, not all transactions can be captured when the system is down, but our customer can capture all inventory movements in their warehouse, and recover much more easily when their system goes down.

Conclusion

We at Accurate Data generally prefer client server architecture to terminal emulation systems, although both have their drawbacks. Our client has managed to combine the best of both systems to minimize his down time, saving significant amounts of money.