Hack My Planet

Day 14: Static IP & Client/Server Chat

Opening Comments

• Today will be composed of team challenges.

• Don't be afraid to ask for help if you don't understand something.

• IF SOMETHING DOESN'T WORK, DOUBLE CHECK YOUR CODE. IF YOU ASK FOR HELP AND IT'S A SYNTAX ERROR, WE WILL NOT HELP YOU.

Python Review

• Loops
• Functions
• Parameters
• White space
• Return()

Function Review

Define a function overlapping() that takes two lists as arguments (parameters) and returns True if they have at least one member in common, False otherwise.

Note: Write this using a nested for-loop

Static IP

• Dynamic vs Static
• Instructions:
  •  
  • Add the following lines at the bottom of the file:
    • Note: X is your assigned number; Ctrl+O to save, Ctrl+X to exit

• Testing:
  • s
  • i
  • You should see the IP address you set in the eth0: entry 

Preparation

• Do all of the following exercises and slides in the directory ~/Documents/python_work

• Download the network.py module with:

wget https://goo.gl/UJMdZh -O network.py --no-check-certificate

Setting Up a Chat Network

• Network your Pi with your neighbor's to test the connection
  • s
    • IP_ADDRESS = your neighbor's static IP
    • DON'T ACTUALLY TYPE IP_ADDRESS
• Set up the chat program
  • Using Geany, create the file 'chat.py'
  • Code is on the following slide

sudo ping IP_ADDRESS -c5

chat.py

# A simple internet-chat application

import network
import sys

def heard(phrase):
  print("them: " + phrase)

if (len(sys.argv) >= 2):
  network.call(sys.argv[1], whenHearCall=heard)
else:  
  network.wait(whenHearCall=heard)

while network.isConnected():
  phrase = input()
  print("me: " + phrase)
  network.say(phrase)

Chatting

• Set up the server Pi with:

• Set up the client Pi with:

python3 chat.py

python3 chat.py SERVER_IP

SERVER_IP is the server's static IP address, DON'T ACTUALLY TYPE SERVER_IP

• Type out a message and press Enter

Editing the Source Code

• Customize your chat by playing around with the code
• Some examples are:
  • Display a welcome message when your program starts
  • Display a welcome message for your caller when they connect
  • When the word "random" is typed, send one of a number of different random messages to your caller (Hint: look at Magic Eight Ball source code)