Presence awareness by wifi

[kgf]

There should be as many ways as possible for people to update their status. Two ways would be to use a barcode tag or a proximity card. This could be implemented using a Raspberry Pi, which could monitor either a proximity card reader, or a video stream from an attached camera. Once it has recognized the presence of one of these tags, it should do an http POST to show this event.
Things to include in the POST:

Raw data from reader or barcode
ID of the raspberrypi
Source of the data (prox reader, video stream, some other scanner, bluetooth, wifi sniffer, et al)
Timestamp of the scan. (This suggests that the pi will need to know the time, which may be tricky)
Some category field, to show that this is a scan. The Pi might also send info POSTs, such as the temperature, or the battery voltage. or anything else)
Please feel free to comment !
@townegr