Making Things Talk

112 MAKING THINGS TALK

Figure 3-11

The finished cat bed (at

right) and a detail of the

sensor pad, which sits

under the cat bed itself. A

bamboo jewelry box from a

nearby gift store houses the

electronics, and matches

the furniture. The USB cable

runs to the computer. Make

sure to secure the wires

throroughly, or the cat may

try to chew on them.

Conclusion

The Internet is actually a network of networks, built up

in multiple layers. Successful network transactions rely

on there being at least one reliable route through the

Net from client to server. Client and server applications

exchange strings of text messages about the files they

want to exchange, transferring their files and messages

over network ports. To communicate with any given server,

you need to know its message protocols. When you do,

it’s often possible to test the exchange between client and

server using a telnet session and typing in the appropriate

messages. Likewise, it’s possible to write programs for a

personal computer or microcontroller to send those same

messages, as you saw in the cat bed project. Now that you

understand how simple those messages can be, you’ll get

the chance to do it without a personal computer in the

next chapter, connecting a microcontroller to the Internet

through a serial-to-Ethernet converter that’s not much

bigger than the microcontroller itself.

X

Now you’ve got an understanding of the ...