Tag: computer science

Using Scratch with Minecraft & Scriptcraft – step by step instructions

As described in my previous posts, I found  Scriptcraft, the Minecraft plugin created by Walter Higgins, to be a very powerful tool for Minecraft modding and also for learning Javascript. I use it myself to learn and also for teaching kids to code as they can see immediately the result of the issued commands. One of the features I love is that it implements a drone, described as “an (invisible) object you create every time you execute any of the building or movement functions”, that is very similar to the turtle from other languages.

While kids aged 10 or more can understand how it works and can learn how to create their own functions, younger ones can be overwhelmed by the syntax rules and the need to create the files or to link additional modules.

I’m teaching coding to some 8 years old kids who are pretty good with Scratch and love playing Minecraft so I searched for a solution to make these apps work together. The first configuration, described in Using Scratch & Scriptcraft (& more) to teach kids programming in Minecraft was very complex, using Scratch offline with experimental extensions, Node RED, mosquitto mqtt broker and Spigot Minecraft server with Scriptcraft with mqtt plugin. It was based  on Dave Locke’s idea for sending commands from Scratch as MQTT messages, presented in  Visual programming and integration with Scratch, Node-Red and MQTT.

Recently I found a simple solution to receive http commands and to pass them to Minecraft server, based on Node.js,  presented by Kevin Whinnery   in Child Processes, Streams, and Minecraft Server Management via Text Message using Node.js. This configuration only needs Node.js to link Scratch with Minecraft, where the commands are interpreted and executed by Scriptcraft.

I will try to present here more in detail all what is needed (you can skip any of the sections below if you already installed the related application):

On the server side:

Spigot MC server

You have to download BuildTools.jar from https://hub.spigotmc.org/jenkins/job/BuildTools/ and the to follow the instructions from https://www.spigotmc.org/wiki/buildtools/. Basically you have to run this command (not to double click on the downloaded file)

java -jar BuildTools.jar

and after a while you will find in the same folder craftbukkit-1.xx.jar and spigot-1.xx.jar. When writing this, latest version is 1.10, so I used the file spigot-1.10.jar.

The next steps are described at https://www.spigotmc.org/wiki/spigot-installation/. Follow them and make sure the server works.


Download scriptcraft.jar from http://scriptcraftjs.org/download/latest/ and copy it in the Minecraft server \plugins subfolder.
Restart the server and you will see something similiar to this in the output console:
[14:04:25 INFO]: [scriptcraft] Enabling scriptcraft v3.2.0-2016-03-19

Scriptcraft will create its own folder structure under the Minecraft server main folder.


Download the pre-built installer for your OS from https://nodejs.org/en/download/, launch it and follow the on-screen instructions.

On the client side

Scratch 2.0 offline

Download it from https://scratch.mit.edu/scratch2download/  (start by installing Adobe Air if it isn’t already installed on your computer)

Minecraft client

Install the PC/Mac version from https://minecraft.net/en/download/. You must have a paid account in order to use it.

Making it all work together

Update: you can find the most recent version of the files below (mc.js, scratch.js and MCextension.json) at https://github.com/mpatrascu/ScratchMC/

Following the installation instructions for MC server you should have created a script or a batch file (depending on the OS) containing a line similar to this (I didn’t use the other parameters):

java -Xms512M -Xmx1G -jar spigot.jar

Instead of using this script to launch the server, you must create a mc.js file in the same folder, where you copy the following text (taking care to keep your previous parameters for spawning the new java process):


// Require Node.js standard library function to spawn a child process
var spawn = require('child_process').spawn;

// Create a child process for the Minecraft server using the same java process
// invocation we used manually before
var minecraftServerProcess = spawn('java', [
    'spigot.jar'] );

// Listen for events coming from the minecraft server process - in this case,
// just log out messages coming from the server
function log(data) {
minecraftServerProcess.stdout.on('data', log);
minecraftServerProcess.stderr.on('data', log);

var http = require("http");

scratchResponse=[];  //stores the IP and current block values in MC for each Scratch client: 

http.createServer(function(request, response) { //communicates with Scratch extension on port 8088
var ip = request.connection.remoteAddress.slice(7);

if (request.url!="/poll"){ //commands from Scratch - URL format is /command/first_param/second_param/../last_param/
    var command=request.url.toString().slice(1);
    minecraftServerProcess.stdin.write('js scratch("' + command + '","' + ip + '")' + '\n');
    if (request.url=="/reset_all"){ //end of Scratch session        
        for(i=0;i<scratchResponse.length; i++){             if (scratchResponse[i].ip==ip){                 position=i;                                 }             }         if (position>-1) scratchResponse.splice(position,1);
        console.log('Scratch client on IP: ' + ip + ' disconnected. Remaining ' + scratchResponse.length + ' connections.');
else{ //polling by Scratch
    bltype = -1;
    bldata = -1;
    result = -1;
    for(i=0;i<scratchResponse.length; i++){
        if (scratchResponse[i].ip==ip){

    response.write("blockType " + bltype + "\nblockData "+bldata + "\nresult " + result);


http.createServer(function(request, response) {  //receives updates from Minecraft server on port 8089 - URL format is /blockType/blockData/IP/
console.log("update information received: " + request.url.toString().slice(1));

for (i=0; i < scratchResponse.length;i++){
if (!found)
    scratchResponse.push({bltype:params[0], bldata: params[1], result: params[2], ip:params[3]});

response.write('ip'+(found?' found':' added to list'));

You invoke this file by typing
>node mc.js
It will launch Minecraft server as a child process and will listen to ports 8088 and 8089. On port 8088 it receives commands and poll requests from Scratch and on port 8089 it receives information from MC server – current block values and result of some operations. You can leave the ports unchanged, or you can choose other values, but you will need to also update the following two files.
In the Scriptcraft plugins folder you have to copy the file scratch.js which interprets commands passed by the Node.js script.
var Drone = require('/drone/drone').Drone
var foreach = require('utils').foreach

var JavaString = java.lang.String;
var http = require('http');
var utils = require('utils');

var scratchReturnAddress = '';

function scratch(command,ip){
    var players = utils.players();    
    var cmd=command.split("/");
    var index=-1;    
    var drona='';

        if (scratchClients[i].ip==ip){
            console.log("target player: "+scratchClients[i].playerName);
            console.log('trying to connect to player ' + cmd[1]);
            for (pl in players){  //use server.getPlayer(playerName)
                if (players[pl].name.toLowerCase()==playerName.toLowerCase()){
                    drona=new Drone (targetPlayer.location);
                    if (index==-1){ //new player
                        scratchClients.push({playerName:playerName, targetPlayer:targetPlayer,drone:drona, ip:ip});
                        echo(targetPlayer, "Connected to Scratch client on IP "+ip);
                    else { //update existing player
            if (index==-1) { //use of other command before connecting to any player
                console.log('Player not found');
                scratchReturn(-1, -1, 'player_not_found', ip); 
            else { //return to Scratch current block
                scratchReturn(bl.typeId, bl.data, 'connected', ip); //updates values for current block to be read by Scratch     
    if (index==-1) { //use of other command before connecting to any player
        console.log('No target player defined');
        scratchReturn(-1, -1, 'no_target_player', ip); 
    console.log("command received -" + cmd[0]+";");
         case 'boxCommand':   
         case 'box':    
        case 'box0':
        case 'box0Command':               
        case 'cylinder':
        case 'cylinder0':
        case 'prism':
        case 'prism':
        case 'rainbow':
        case 'bed':
        case 'torch':

        case 'stairs':

        case 'wallsign':
            for (i=1; i<5; i++)
        case 'summon':   //summons mobs using Scriptcraft predefined drone's summon method
            console.log("summon "+cmd[1]);
            drona.spawn(cmd[1]) ;           
            break ;
        case 'moveDrone':
            console.log("before moveDrone: " + parseInt(10*drona.x)/10 + ":" + parseInt(10*drona.y)/10 + ":" + parseInt(10*drona.z)/10);
                case 'reset':
                    drona=new Drone (targetPlayer.location);
                case 'up':
                case 'down':
                case 'left':
                case 'right':
                case 'fwd':
                case 'back':
                case 'turn':
                case 'save_chkpt':
                case 'goto_chkpt':
            //console.log("after moveDrone: " + parseInt(100*drona.x)/100 + ":" + parseInt(100*drona.y)/100 + ":" + parseInt(100*drona.z)/100);            
        scratchReturn(bl.typeId, bl.data, 'ok', ip); //updates values for current block to be read by Scratch

function scratchReturn(bltype, bldata, result, ip){ //updates values for current block to be read by Scratch
    var http = require('http');
    http.request( scratchReturnAddress + bltype + '/' + bldata + '/' + result + '/' +ip,function(responseCode, responseBody){console.log(  responseBody );});

It keeps track of IPs for each client so you can have multiple connections from different computers. You can leave for scratchReturnAddress as the processes run on the same machine, and the port must be the same as the second one from mc.js (8089).
On the client you will have to use MCextension.json file for Scratch. The port must be the same as the first port defined in mc.js (8088), but you need to update the IP address to match the server’s address if you are using a separate computer. You should also update the default player, replacing playerName with the one you will use most frequently.
   "extensionName": "Minecraft",
   "extensionPort": 8088,
   "useHTTP": true, 
   "blockSpecs": [
     [" ", "Connect User %s", "connect","playerName"],
     [" ", "box blType:%n blData:%n width:%n height:%n depth:%n", "boxCommand", 1, 0, 1, 1, 1],
     [" ", "box0 blType:%n blData:%n width:%n height:%n depth:%n", "box0Command", 1, 0, 1, 1, 1],
     [" ", "prism blType:%n blData:%n width:%n depth:%n", "prism", 1, 0, 3, 1],
     [" ", "prism0 blType:%n blData:%n width:%n depth:%n", "prism0", 1, 0, 3, 1],
     [" ", "cylinder blType:%n blData:%n radius:%n height:%n", "cylinder", 1, 0, 5, 1],
     [" ", "cylinder0 blType:%n blData:%n radius:%n height:%n", "cylinder0", 1, 0, 5, 1],    
     [" ", "stairs blType:%n blData:%n width:%n height:%n", "stairs", 1, 0, 1, 1],    
     [" ", "rainbow radius:%n", "rainbow", 12],     
     [" ", "place bed", "bed"],
     [" ", "hang torch", "torch"],
     [" ", "wallsign message :%s :%s :%s :%s", "wallsign", "", "", "", ""],
     [" ", "move drone %m.commands %n", "moveDrone", "fwd", 1],
     [" ", "summon %m.entities", "summon", "Chicken"],
     ["r", "blockType", "blockType"],
     ["r", "blockData", "blockData"],
     ["r", "result", "result"]
        "commands": ["fwd", "back", "left", "right", "up", "down", "turn", "reset", "save_chkpt", "goto_chkpt"],
        "entities": ["Chicken", "Cow", "Wolf", "Pig", "Sheep", "Rabbit", "Horse", "Ocelot", "Villager", "Zombie", "Skeleton", "Creeper", "Spider"]
Pressing Shift and clicking File in Scratch will provide access to Import experimental HTTP extension (the last option in the list) for opening the MCextension.json file.
By doing this, in the More blocks category you will have access to new blocks and variables. Before issuing any other command you should use Connect User and the name of a player with an open MC session on the server as a parameter. When connected, it will put a message in Minecraft chat and will automatically create a drone at player’s position, which will execute all the commands.
The new blocks defined in MCextension.json file try to replicate some of the functions that Walter Higgins defined in the drone plugin. For short descriptions of those functions and needed parameters please check https://github.com/walterhiggins/ScriptCraft/blob/master/docs/API-Reference.md#drone-plugin.
The box, prism, cylinder and rainbow are used to create solid structures, while box0, prism0 and  cylinder0  are for hollow structures – just walls without ceiling and floor.You can specify the material – block type and block data – and the dimensions.
Stairs, bed, torch and wallsign are used to place specific elements which must take into account player’s orientation.
The move drone function tells the drone where to move. The last drone position will be remembered so if you want to start again from the player’s position, you have to use move drone reset or Connect user again.
Summon is used to spawn the mobs from the predefined list. You can update this list for new mobs.
At the end of the file there are some variables updated by the Minecraft server:  blockType and blockData contain information about the block where the drone is, while result contains the result of last executed command.
If you want to check the values for blockType and blockData, you should insert a delay  of at least 0.2 secs (using standard Scratch block) after the last move drone instruction before using them.

Known issues

Sometimes commands are not executed in order, especially when the server is busy. It’s better to avoid launching command sequences from more than one computer at the same time, although it could work.
move drone save_chkpt and move drone goto_chkpt don’t work yet.

Future developments

Hunting for bugs, adding new functions, showing the equivalent Javascript commands on screen.



Piper – Play Minecraft. Build Electronics


Piper is a complete computer based on Raspberry Pi and contains a customized version of Minecraft that can interact with a DYI controller and external  lights.

The Pi comes with a 7″ screen, power bank, mouse, memory card with all needed software and accessories to create your the hardware that interacts with Minecraft – wires, boards, switches, buttons, lights. The player receives in-game instructions for putting them in place and once done he will gain new power-ups.

Read more on http://www.withpiper.com/

Which Programming Language Should I Learn First?

Carlcheo.com guide on choosing the programming language to learn

So you want to learn programming. Maybe you have asked your developer friends for recommendations and get different answers. They explained with terms that you don’t understand (what is object-oriented?!). To help you to pick your first programming language to learn, here is an easy-to-understand infographic that recommends the best option, depending on your purpose and interest. Details such as learning difficulty, popularity, and average salary for each computer programming language are provided too.

Infographic: Which Programming Language Should I Learn First

full guide plus a list of best programming tools and resources for each programming language on http://carlcheo.com/startcoding

How to Teach Computing

Little Big Planet 2 – Logic Tutorials by QuietlyWrong on PSN Forum

Very useful tutorials for powerful logic capabilities of Little Big Planet 2, created by user QuietlyWrong on http://community.eu.playstation.com

LBP2 Logic Level Link

#1 Boolean Logic, AND and OR
Welcome to the first in a series of articles in which I hope to explain as much as I can about using Logic in LBP2. I’m going to start from the very beginning and work up to some complex systems with a load of examples on the way. Please give me feedback to stop me getting bored!…

#2 Microchips in LBP2
In the first tutorial, I was building the logic right on the level. This isn’t normally the best place to put it. LBP2 provides you with a gadget that is specially designed to hold logic circuits…

#3 NOT, truth tables, XOR and inversions
So far, we’ve looked at ways of combining signals from two or more inputs. If you remember back to the first tutorial, we saw how the AND gate responds if ALL of the inputs are on and the OR gate responds if ANY of the inputs is on.
The NOT gate is unique in that it only operates on a single input – a single wire…

#4 Timers and Counters
The next thing I’d like to talk about are timers and counters. These are incredibly useful – so useful, in fact, that when I was trying to come up with logic examples for the tutorials and the tutorial level, I struggled to avoid introducing one or the other of these ‘advanced logic’ gadgets. They really are the bedrock of gameplay logic, and it’s worth spending some time getting to know these two gadgets and how the various tweak options work…

Teaching Kids Programming

A new resource for teaching Programming to kids, based on the “Intentional Method”:


Teaching Kids Programming

The TKP Intentional Method

We at ‘Teaching Kids Programming’ have invented and use a new method of teaching children programming. We call this the intentional method. It consists of courseware and teaching techniques. All of this material is freely available to use and improve.  The Intentional Method simply stated is teaching by guiding pairs of children from English comments (the intention) to code those comments correctly into some other programming language.  The core programming language that we use is Microsoft SmallBasic.  We have also developed Intentional teaching materials for Java, T-SQL and for Microsoft Kodu (visual programming).  There are a few key concepts that we attempt to follow in writing and in teaching all our TKP lessons (recipes).  These concepts include the following:

1) One line of English = One line of code

2) Code one line and then run your program to verify that your translation was correct

3) After correctly coding a line of English (comment), then delete that line

We have done this mainly with the SmallBasic Recipes, but have extended to a few other classes.

More Information:
Who are our Teachers? 
Our teachers are volunteers. They come from the professional developer community. We’ve also done work with classroom teachers. We’ve heard from homerschoolers as well. If you’d like to teach our courseware we recommend you complete the courseware, as a student, first. Then process to our ‘teaching tips` sections(s) of this website. In particular, you may want to take a look at our teaching training videos.


Computer Science education week – Hour of code



An Hour of Code for every student

Computer Science is a foundation for every student. Help introduce it to 10 million.
All it takes is one Hour of Code.

Join us
Ages 6-106
No math needed
No computers either
11,634 events, 1,897,124 students, 144 countries

What’s an Hour of Code?
It’s a one-hour introduction to computer science, designed to demystify “code” and show that anyone can learn the basics to be a maker, a creator, an innovator.

We’ll provide a variety of self-guided tutorials that anybody can do, on a browser, tablet, or smartphone. We’ll even have unplugged tutorials for classrooms without computers. No experience needed.

Why computer science?
Computer science provides a foundation for virtually any career – everybody can benefit from learning the basics. Visit Code.org for inspiration.

Other CSEdWeek events
Computer Science Education Week is observed each year, in recognition of the birthday of computing pioneer Admiral Grace Murray Hopper (December 9, 1906).

The Hour of Code is just one of many different events planned for CSEdWeek. If you are a CS teacher, see our Participation Kit for CS Teachers, and if you plan a special event tell us about it so we can celebrate your hard work.

Europe Code Week


Europe Code Week

About the initiative and resources

The initiative was launched by Neelie Kroes’ Young Advisors with the support from DG Connect at the European Commission. Sounds fancier than it really is. We’re just a bunch of young people with a dream of a world where all sort of crazy ideas are given a chance to change the world. But it’s not really about us.

It’s about Pia, who felt like she had to study law, even though she always enjoyed maths and playing with computers. It’s about Mark, who has the idea for a better social network, but can’t build it on his own. It’s about Alice, who dreams about making robots because her parents don’t allow her to have a cat.

It’s about Karl, who’s bored of his career in marketing and wants a new challenge and his colleague, Mila, a project manager who just can’t seem to speak the same language as software developers on the project. It’s about Linda, who wants to start her own company, it’s about Leo, a talented designer, who wants to show his clients how his design really works, not just looks like. We’re sure you’ve heard many stories like these.

It’s about those of you who are already helping these dreams come true.
Actually, it’s about all of us. Our future. Technology is shaping our lives, but we’re letting a minority decide what and how we use it for. We can do better than just sharing and liking stuff. We can bring our crazy ideas to life, build things that will bring joy to others.

It’s never been easier to make your own app, build your own robot, or invent flying cars, why not! It’s not an easy journey, but it’s a journey full of creative challenges, a supportive community, and tons of fun. Are you ready to accept the challenge and become a maker?



20 resources you can use to teach beginners about computer programming

Published on 23 Nov 2013

@daniel_oreilly from @CoderDojoArmagh compiled a great presentation with ideas/tools/resources that can help you introduce programming to your classroom or computer club.