Multiplayer Game Programming

Tuesday, June 21

Diablo Valley College is having severe network problems, so the kids' computers are unusable today.

Plan

Dave shows his Roomba, the robotic vacuum cleaner
Is it a computer?
Discussion of programming
What decisions? State? Loops?

Animusic, play tracks from DVD
How was this done? What programming is involved

Kids introduce selves, talk about programming experience

Program demos
Teaching assistants
Chris
Ian
Mine (source in DBSchools project on sourceforge.net)
Math quiz multiplayer game
others (see Java Run dialog)
Run python client to connect to Java server

Introduction to TCP/IP client/server concepts

Reflection

This is a small class. Lots of individual attention. Two students to each teacher/TA. The kids learned:

Multiplayer games often consist of a server and one or more clients.
To connect to a server the client must know the server's name or IP address, and the port the service is on.
A single computer may offer several services: Web, mail, and various games, for example.

I ran a simple server, written in Java, which accepted connections on port 8000. I showed how we can use the "netstat -a" command to confirm that the server is indeed listening on that port. We ran a short Python program which connected to the server and interacted with it. The server is a simple text-based "game" (or the beginning of one, perhaps). The server says "Welcome" and then waits for a command. If a command it recognizes is issued, it sends a certain response.

Then I showed how one can use the telnet command (telnet localhost 8000) to connect to the server, without using a custom-written client.

We had a review where everybody told something they learned in the class.

We watched a Roomba robotic vacuum cleaner and talked about how it works--what kind of programming it must contain. We wonder what kind of awareness it has, and talked about it as if it had human characteristics. I told everybody that that's called "anthropomorphization," and cautioned them, "Don't anthropomorphize computers. They hate it when you do that!" (One of my favorite jokes.) Half of them laughed--hard. I told the rest to keep thinking about it.

Wednesday, June 22

Plan

All classes: review, student introductions

Python: Continue Lesson One (see "Lesson One" announcement)

Squeak: Tutorial 3 from squeakland.org: make a car that drives by itself on a track. Then apply the new skills to make something of your own invention. Here are some ideas:

A skier going down a slope
A plane that flies into a cloud, then does a 180-degree turn
A robotic vacuum cleaner moving around a room with obstacles
Two people that avoid walking into each other

Multiplayer game programming: Demo of the "math quiz game" (see sourceforge dbschools). Break into three groups. Students learn to use Eclipse to create Java programs. Introduction to Java. Creating a ServerSocket. Connecting to it with telnet or a client in Java or Python.

Questions for students:
What is Eclipse?
What is a class?
What is a ServerSocket?
What does it mean to "connect"?

Reflection

We had a review where taking turns, each student chose another student and asked him a question about a key topic from yesterday. It was very effective.

We split into groups of two and learned how to use Eclipse (eclipse.org) to create a Java project and Java class file. The kids liked the individual attention, and seemed to get the concepts. We didn't have a quiz, so we'll see tomorrow in the review how much they retained. The network is still down here so we can't use the QuickQuiz program (dbschools.com) for real time assessments.

We considered how different it is creating a "Hello World" program in Java from doing it in Python. In Python, of course, it's something like:

print 'Hello World'

and in Java, it's more like:

public class Hello {
    public static void main(String[] args) {
        System.out.println("Hello World");
    }
}

There are quite a few more concepts to cover in Java.

I told a little of the history of free (free as in freedom) software and open-source software, and I said that all of my program examples are in the DBSchools project on sourceforge.net.

Thursday, June 23

Plan

Croquet demo

Continue: Introduction to Java. Creating a ServerSocket. Connecting to it with telnet or a client in Java or Python.

Reflection

TA Chris Gibson gave an very interesting ten-minute demo of Croquet (www.opencroquet.org). The kids were fascinated by it. We will think of how we might be able to use it in the classes.

We continued with small group instruction in Java, using the ServerSocket class. Trying to explain a line like

ServerSocket serverSocket = new ServerSocket(1000)

is quite a challenge. I'm leaning towards using Python more than Java.

Tuesday, June 28

Plan

Continue learning Java and ServerSocket. Learn Socket and connect to the ServerSocket with Socket.

Reflection

We had a "checkpoint," where I asked everyone to create a Java class with a ServerSocket that accepts a connection, in ten minutes, using their notes or a set of Web-based resources. None of the six succeeded, but one came very close. I hope everyone learned the value of notetaking. I again thought of doing less with Java and more with Python.

Wednesday, June 29

Plan

Walkthrough of the math quiz game. Getting source code from sourceforge.

Reflection

We learned about ping and traceroute, and finding out what our IP address is. We pinged several machines around the globe and compared the response times. With traceroute we talked about how there are usually several routers in between the endpoints of a connection.

I ran the math quiz game, and the kids connected to it with telnet, and we played for a few minutes.

We learned how to navigate through the DBSchools sourceforge project CVS tree, and we looked at the code for the binary clock and the math quiz game.

I wore my shirt: "There are only 10 types of people in the world: Those who understand binary and those who don't" and that sparked a conversation about the binary number system. We played with the Binary LED Decoding Game (http://davebsoft.com/Computer_Training_for_Kids/Class_Materials/Runnable_Applications/index.html) and kids got the hang of that.

Thursday, June 30

Plan

Getting started with Pygame and networking in Python

Reflection

Today we left Java for awhile and introduced Pygame, similarly to the Python class. One student was able to create a second graphic in the bouncing ball program, with very little help. I announced that we will create a multiplayer game using Pygame and network programming.

Tuesday, July 5

Plan

Introduction to Squeak. TCP client/server programming in Squeak.

Reflection

We had a good introduction to Squeak. I'm getting ideas from the Squeak community on how best to use Squeak for this class.

Wednesday, July 6

Plan

Squeak's collaborative features: dropping a Morph on another student's world.

Discussion of exchanging data between clients and server in Squeak.

s_Socket newTCP
s listenOn: 5000
s2_Socket newTCP
s2 connectTo: (NetNameResolver addressFromString: '127.0.0.1') port: 5000
s sendData: 'abc'
s2 receiveData

Reflection

Playing with Sockets went fairly well, but wasn't nearly as exciting as Squeak's collaborative features.
 

Thursday, July 7

Plan

QuickQuiz:
telnet
ping
traceroute (tracerte)
netstat
ipconfig
ServerSocket
what info to connect to a server
number 5 in binary
Sourceforge
open source
Richard Stallman

Lesson: Walkthrough of the math quiz game

Further play/experimentation with Squeak's collaborative features

Reflection

The kids did pretty well on the quiz. One boy was the clear winner. This boy took notes every day. Most of the rest did very well. I think we were successful in teaching TCP client/server concepts and in building a foundation for learning to create multiplayer games. I was disappointed that we didn't actually have a multiplayer game at the end. This is partly due to my changing "preferred" languages twice, and perhaps because the class is too ambitious for just 9 hours with kids of this age. What will we change for the second session, starting next week?