Lately i have been trying to make munication between minecraft server (running with Java) and scratch (running with JavaScript). I have written the code in java already:

package me.yotam180;

import java.io.IOException;
import java.io.OutputStream;
import java.InetSocketAddress;
import java.util.HashMap;
import java.util.Map;

import org.bukkit.Bukkit;

import .sun.httpserver.HttpExchange;
import .sun.httpserver.HttpHandler;
import .sun.httpserver.HttpServer;


public class HttpProcessor {
     public MainClass plugin;
    public HttpProcessor (MainClass plug) throws IOException {
        plugin = plug;
        plugin.getLogger().info("CREATED HTTTP PROCESSOR");
        HttpServer server = HttpServer.create(new InetSocketAddress(9090), 0);
        server.createContext("/pollplayer", new PollPlayerHandler());
        server.createContext("/killplayer", new KillPlayerHandler());
        plugin.getLogger().info("STARTED HTTTP SERVER");
        server.setExecutor(null); // creates a default executor
        server.start();
    }

    static class PollPlayerHandler implements HttpHandler {

        @SuppressWarnings("deprecation")
        @Override
        public void handle(HttpExchange httpExchange) throws IOException {
            // TODO Auto-generated method stub
            Map <String,String>parms = HttpProcessor.queryToMap(httpExchange.getRequestURI().getQuery());
            StringBuilder response = new StringBuilder();
            response.append(Bukkit.getPlayer(parms.get("name")).getLocation().toString());
            HttpProcessor.writeResponse(httpExchange, response.toString());
        }
    }
    static class KillPlayerHandler implements HttpHandler {

        @SuppressWarnings("deprecation")
        @Override
        public void handle(HttpExchange httpExchange) throws IOException {
            // TODO Auto-generated method stub
            Map <String,String>parms = HttpProcessor.queryToMap(httpExchange.getRequestURI().getQuery());
            Bukkit.getPlayer(parms.get("name")).setHealth(0);
            HttpProcessor.writeResponse(httpExchange, "SUCCESS");
        }
    }

    public static void writeResponse(HttpExchange httpExchange, String response) throws IOException {
        httpExchange.sendResponseHeaders(200, response.length());
        OutputStream os = httpExchange.getResponseBody();
        os.write(response.getBytes());
        os.close();
      }

    public static Map<String, String> queryToMap(String query){
        Map<String, String> result = new HashMap<String, String>();
        for (String param : query.split("&")) {
            String pair[] = param.split("=");
            if (pair.length>1) {
                result.put(pair[0], pair[1]);
            }else{
                result.put(pair[0], "");
            }
        }
        return result;
      }

}

Now I have to make the scratch side HTTP Client. Every way i tried, It just didn't work. I try to open my browser, i write http://localhost:9090/pollplayer?name=yotam_salmon and it reports my player location beautifully. Now my problmem is the scratch JS.

Here it is:

new (function () {
    var ext = this;

    // Cleanup function when the extension is unloaded
    ext._shutdown = function () { };

    // Status reporting code
    // Use this to report missing hardware, plugin or unsupported browser
    ext._getStatus = function () {
        return { status: 2, msg: 'Ready' };
    };

    ext.get_Player = function (name, callback) {
        //in this function i need to call http://localhost:9090/pollplayer?name= + name, wait for the response and then callback it.
        //the response can't be "return response;", and it cannot be call backed from another function. If this function was called, it
        //has to report the location back as a string
    };

    // Block and block menu descriptions
    var descriptor = {
        blocks: [
            ['R', 'location of %s', 'get_Player', 'Player'],
        ]
    };

    // Register the extension
    ScratchExtensions.register('ScratchCraft', descriptor, ext);
})();

I cannot format my JS code differently, because Scratch works only with this format.(It is explained here: /). In the ext.get_Player function i have to go to the Java http server, request /pollplayer?name= + name, and callback it .

I would be happy to get a solution :) Thanks!

Lately i have been trying to make munication between minecraft server (running with Java) and scratch (running with JavaScript). I have written the code in java already:

package me.yotam180;

import java.io.IOException;
import java.io.OutputStream;
import java.InetSocketAddress;
import java.util.HashMap;
import java.util.Map;

import org.bukkit.Bukkit;

import .sun.httpserver.HttpExchange;
import .sun.httpserver.HttpHandler;
import .sun.httpserver.HttpServer;


public class HttpProcessor {
     public MainClass plugin;
    public HttpProcessor (MainClass plug) throws IOException {
        plugin = plug;
        plugin.getLogger().info("CREATED HTTTP PROCESSOR");
        HttpServer server = HttpServer.create(new InetSocketAddress(9090), 0);
        server.createContext("/pollplayer", new PollPlayerHandler());
        server.createContext("/killplayer", new KillPlayerHandler());
        plugin.getLogger().info("STARTED HTTTP SERVER");
        server.setExecutor(null); // creates a default executor
        server.start();
    }

    static class PollPlayerHandler implements HttpHandler {

        @SuppressWarnings("deprecation")
        @Override
        public void handle(HttpExchange httpExchange) throws IOException {
            // TODO Auto-generated method stub
            Map <String,String>parms = HttpProcessor.queryToMap(httpExchange.getRequestURI().getQuery());
            StringBuilder response = new StringBuilder();
            response.append(Bukkit.getPlayer(parms.get("name")).getLocation().toString());
            HttpProcessor.writeResponse(httpExchange, response.toString());
        }
    }
    static class KillPlayerHandler implements HttpHandler {

        @SuppressWarnings("deprecation")
        @Override
        public void handle(HttpExchange httpExchange) throws IOException {
            // TODO Auto-generated method stub
            Map <String,String>parms = HttpProcessor.queryToMap(httpExchange.getRequestURI().getQuery());
            Bukkit.getPlayer(parms.get("name")).setHealth(0);
            HttpProcessor.writeResponse(httpExchange, "SUCCESS");
        }
    }

    public static void writeResponse(HttpExchange httpExchange, String response) throws IOException {
        httpExchange.sendResponseHeaders(200, response.length());
        OutputStream os = httpExchange.getResponseBody();
        os.write(response.getBytes());
        os.close();
      }

    public static Map<String, String> queryToMap(String query){
        Map<String, String> result = new HashMap<String, String>();
        for (String param : query.split("&")) {
            String pair[] = param.split("=");
            if (pair.length>1) {
                result.put(pair[0], pair[1]);
            }else{
                result.put(pair[0], "");
            }
        }
        return result;
      }

}

Now I have to make the scratch side HTTP Client. Every way i tried, It just didn't work. I try to open my browser, i write http://localhost:9090/pollplayer?name=yotam_salmon and it reports my player location beautifully. Now my problmem is the scratch JS.

Here it is:

new (function () {
    var ext = this;

    // Cleanup function when the extension is unloaded
    ext._shutdown = function () { };

    // Status reporting code
    // Use this to report missing hardware, plugin or unsupported browser
    ext._getStatus = function () {
        return { status: 2, msg: 'Ready' };
    };

    ext.get_Player = function (name, callback) {
        //in this function i need to call http://localhost:9090/pollplayer?name= + name, wait for the response and then callback it.
        //the response can't be "return response;", and it cannot be call backed from another function. If this function was called, it
        //has to report the location back as a string
    };

    // Block and block menu descriptions
    var descriptor = {
        blocks: [
            ['R', 'location of %s', 'get_Player', 'Player'],
        ]
    };

    // Register the extension
    ScratchExtensions.register('ScratchCraft', descriptor, ext);
})();

I cannot format my JS code differently, because Scratch works only with this format.(It is explained here: http://llk.github.io/scratch-extension-docs/). In the ext.get_Player function i have to go to the Java http server, request /pollplayer?name= + name, and callback it .

I would be happy to get a solution :) Thanks!

• java
• javascript
• minecraft
• bukkit
• mit-scratch

Share Improve this question Follow edited Mar 15, 2015 at 16:02 Yotam Salmon asked Mar 14, 2015 at 12:29 Yotam SalmonYotam Salmon 2,41111 gold badge2323 silver badges3636 bronze badges 8

• sun is deprecated. Use a proper HTTP connection, such as the dependency Apache HTTP Library. – Unihedron Commented Mar 15, 2015 at 6:05
• I'm sure you know what you're doing, but the boilerplate code in llk.github.io/scratch-extension-docs looks different from yours; why is that? Have you tried the 'Reporter blocks that wait' code sample (which is very similar to what you want), and did it work? Have you checked your web browser's javascript console for possible errors? Have you tried a packet analyzer to verify the correct URL is sent to the Minecraft server? – Ruud Helderman Commented Mar 15, 2015 at 20:06
• Firstly, Thanks a lot for the answer. The reporterblocks that wait is exactly what I want, but I can't get it to work. I tried the weather example, and it worked. After that, I changed the url in the $.ajax part to my java server and it stopped working. I think that I'm maybe providing the HTTP responses wrong. It's kind of my 1st time with real javascript, so I didn't know that there is a console... How do I open it ni Chrome? and no, I didn't use a packet analyzer, but I'll try. Tommorow in my time zone I will try making different ways of HTTP responses, but thank you. – Yotam Salmon Commented Mar 15, 2015 at 21:09
• If the code sample breaks when changing to your own URL, then that suggests the fault is in the Java part. A packet analyzer shows the 'weather' URL returns an Access-Control-Allow-Origin response header, as proposed here. Your Java code should do the same, otherwise the web browser might reject your URL for being an (unsafe) cross-origin request. In Google Chrome, you will find the JavaScript console in the menu under 'More tools' (shortcut: Ctrl+Shift+J). – Ruud Helderman Commented Mar 16, 2015 at 12:41
• I added the line httpExchange.getRequestHeaders().set("Access-Control-Allow-Origin", "*"); in the response handling, but now it doesn't show the eresponse even in the browser :( – Yotam Salmon Commented Mar 16, 2015 at 19:33

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1 Answer 1

Sorted by: Reset to default 8

The solution was very simple. I just had to add an header of "Allow-Access-Cross-Origin", and it was solved.

httpExchange.getResponseHeaders().set("Access-Control-Allow-Origin", "*");
httpExchange.getResponseHeaders().set("Content-Type", "text/plain");