Why do I need a processing code when I pair Arduino with bluetooth

[marellasunny]

Why do I need a "processing" code when I pair Arduino with bluetooth

I have a need to connect my [Arduino+Bluetooth dongle JY-MCU V1.02] to my laptop in-built bluetooth device.Most forums suggest using a processing code to go ahead and do this http://www.instructables.com/id/Success-Using-the-JY-MCU-linvor-Bluetooth-Module/?ALLSTEPS.
"Demonstration of a Processing client searching for and connecting to a service."
Name of processing library: Bluetoothdesktop library by extrapixel.

Now,I am a mechanical engineer with very little/no idea of how the processing code goes about in establishing the bluetooth device on my laptop as master. In simple words,it looks like the processing code controls the devices in-built in my laptop whereas the arduino code controls the signals to and from the arduino.Is that right?

 

[JeffEvarts]

Fair question!

The short answer is: information security. If you own the laptop, you might not want to go connecting to any random (potentially hostile, malware-laden) bluetooth device that wanders into range. Likewise if you own a bluetooth device (say, your insulin pump) you might not want anyone with a laptop to gain control of it. Entering the code secures ONE of those connection directions (usually convinces the device that the laptop is an "authorized" thing to talk to) but in an ideal world, both the laptop and the device would generate a code, and you wouldenter each code on the other device for bidirectional security.
-Jeff