In the previous chapters, you’ve assumed that identity equals address.
Once you knew a device’s address on the network, you started talking.
Think about how disastrous this would be if you used this formula in
everyday life: you pick up the phone, dial a number, and just start talking.
What if you dialed the wrong number? What if someone other than the
person you expected answers the phone?
Networked objects mark the boundaries of networks, but not of the
communications that travel across them. We use these devices to send
messages to other people. The network identity of the device and the
physical identity of the person are two different things. Physical identity
generally equates to presence (is it near me?) or address (where is it?),
but also takes into consideration network capabilities of the device and the
state it’s in when you contact it. In this chapter, you’ll learn some methods
for giving physical objects network identities. You’ll also learn ways that
devices on a network can learn each other’s capabilities though the
messages they send and the protocols they use.
Sniff, a toy for sight-impaired children, by Sara Johansson.
The dog’s nose contains an RFID reader. When he detects RFID-tagged objects, he gives sound and tactile feedback,
a unique response for each object. Designed by Sara Johansson, a student in the Tangible Interaction course at
the Oslo School of Architecture and Design, under the instruction of tutors Timo Arnall and Mosse Sjaastad.
Photo courtesy of Sara Johansson.
Making_Things_Talk.indb 295 11/13/09 4:56 PM

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