Running a Closed Loop System

Confirming Pick-to-Light Picks

Running a closed-loop system lets your server to know whether or not the picker acknowledged the pick-to-light pick.

Modern devices support barcodes and QR-Codes that are a natural choice for transaction confirmations.  In fact, the encoded data can be customized for each individual pick.

These options are unavailable on our Classic devices, however, so feedback requires the user to set up his/her own server to receive feedback information.

For modern or classic device users that need callback confirmations, there is a hidden parameter that the user can add to the QueryString URL, called a transaction ID.  (The REST API also supports this parameter.)

https://www.voodoodevices.com/api/D4F660:AFA0CB/pick/Jessica Pick 3/SKU:001256/140,c5,4/20/transactionID001

The user chooses a transaction ID to identify the particular call to the device.  The user can choose whether is a random number, a counter, or a nonce.  It is up to the user to choose. (The REST API simply refers to this parameter as ‘nonce’.)

If the transaction ID is added to the URL, then after the picker presses the button on the device, voodoodevices.com makes a URL call to your server like this:

https://your.domain.com/voodoodevices/transactionID001/ack

If the picker does not press the button (within the time limit specified in the initial URL call), voodoodevices.com makes a URL call to:

https://your.domain.com/voodoodevices/transactionID001/nack

If the device was out of range, or there was some problem communicating with the device, voodoodevices.com does not make a follow-up URL call.*

The server receives one of the following:

  1. An ack message, indicating that the picker pushed the button
  2. A nack message, indicating that the device timed out
  3. No response, indicating that the device is out of range or some other problem *

The prefix of the response URL above, https://your.domain.com/voodoodevices/…, is preapproved and set manually in voodoodevices.com for your account.  It can be any URL prefix you choose, using HTTP or HTTPS.  Contact us to register your URL.

Warning:  Should you choose to use a Closed Loop System setup, you need a very reliable communication system between your server and voodoodevices.com on the cloud.

* After we designed this system, some customers expressed a desire to get a response back to every request.  We therefore added a feature that can send back a ‘lost’ message for devices that does not produce an ack or a nack. Just let us know if you would like us to enable this for your account.

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