Testing the Impossible: JavaScript in a Web Page

18. November, 2008

How do you run JUnit tests on JavaScript in a web page? Impossible?

Here is what you need: First, get a copy of Rhino (at least 1.6R7). Then, save a copy of the JavaScript code at the bottom as “env.js“. And here is the setup code for the JUnit test:

    Context cx;
    Global scope;

    public void setupContext () throws IllegalAccessException,
            InstantiationException, InvocationTargetException
    {
        cx = Context.enter();
        scope = new Global();
        scope.init (cx);

        addScript(cx, scope, new File ("html/env.js"));

        File f = new File ("html/demo.html");
        cx.evaluateString(scope, 
                "window.location = '"+f.toURL()+"';\n"
                + "", "setupContext", 1, null);
    }

    public void addScript (Context cx, Scriptable scope, File file) throws IOException
    {
        Reader in = new FileReader (file);
        cx.evaluateReader(scope, in, file.getAbsolutePath(), 1, null);
    }

This will load “demo.html” into the browser simulation. The problem here: The loading is asynchronous (just like in a real browser). Now what? We need synchronization:

import org.mozilla.javascript.ScriptableObject;

public class JSJSynchronize extends ScriptableObject
{
    public Object data;
    public Object lock = new Object ();
    
    public JSJSynchronize()
    {
    }
    
    @Override
    public String getClassName ()
    {
        return "JSJSynchronize";
    }
    
    public Object jsGet_data()
    {
        synchronized (lock)
        {
            try
            {
                lock.wait ();
            }
            catch (InterruptedException e)
            {
                throw new RuntimeException ("Should not happen", e);
            }
            
            return data;
        }
    }

    public void jsSet_data(Object data)
    {
        synchronized (lock)
        {
            this.data = data;
            lock.notify ();
        }
    }
    
    public Object getData()
    {
        synchronized (lock)
        {
            try
            {
                lock.wait ();
            }
            catch (InterruptedException e)
            {
                throw new RuntimeException ("Should not happen", e);
            }
            
            return data;
        }
    }

    public void setData(Object data)
    {
        synchronized (lock)
        {
            this.data = data;
            lock.notify ();
        }
    }
    
}

With this code and “window.onload”, we can wait for the html to load:

        JSJSynchronize jsjSynchronize;
        ScriptableObject.defineClass(scope, JSJSynchronize.class);
        
        jsjSynchronize = (JSJSynchronize)cx.newObject (scope, "JSJSynchronize");
        scope.put("jsjSynchronize", scope, jsjSynchronize);

        cx.evaluateString(scope, 
                "window.location = '"+f.toURL()+"';\n" +
                "window.onload = function(){\n" +
                "    print('Window loaded');\n" +
                "    jsjSynchronize.data = window;\n" +
                "};\n" +
                "", "", 1, null);

        ScriptableObject window = (ScriptableObject)jsjSynchronize.getData();
        System.out.println ("window="+window);
        ScriptableObject document = (ScriptableObject)scope.get ("document", scope);
        System.out.println ("document="+document);
        System.out.println ("document.forms="+document.get ("forms", document));
        ScriptableObject navigator = (ScriptableObject)scope.get ("navigator", scope);
        System.out.println ("navigator="+navigator);
        System.out.println ("navigator.location="+navigator.get ("location", navigator));

        // I've been too lazy to parse the HTML for the scripts:
        addScript(cx, scope, new File ("src/main/webapp/script/prototype.js"));

Slightly modified version of env.js, original by John Resig (original code):

/*
 * Simulated browser environment for Rhino
 *   By John Resig <http://ejohn.org/>
 * Copyright 2007 John Resig, under the MIT License
 * http://jqueryjs.googlecode.com/svn/trunk/jquery/build/runtest/
 * Revision 5251
 */

// The window Object
var window = this;

// generic enumeration
Function.prototype.forEach = function(object, block, context) {
 for (var key in object) {
  if (typeof this.prototype[key] == "undefined") {
   block.call(context, object[key], key, object);
  }
 }
};

// globally resolve forEach enumeration
var forEach = function(object, block, context) {
 if (object) {
  var resolve = Object; // default
  if (object instanceof Function) {
   // functions have a "length" property
   resolve = Function;
  } else if (object.forEach instanceof Function) {
   // the object implements a custom forEach method so use that
   object.forEach(block, context);
   return;
  } else if (typeof object.length == "number") {
   // the object is array-like
   resolve = Array;
  }
  resolve.forEach(object, block, context);
 }
};

function collectForms(document) {
 var result = document.body.getElementsByTagName('form');
 //print('collectForms');
 document.forms = result;
  
 for (var i=0; i<result.length; i++) {
     var f = result[i];
     f.name = f.attributes['name'];
     //print('Form '+f.name);
     document[f.name] = f;
     f.elements = f.getElementsByTagName('input');
     
     for(var j=0; j<f.elements.length; j++) {
         var e = f.elements[j];
         var attr = e.attributes;
         
         //forEach(attr, print);
         e.type = attr['type'];
         e.name = attr['name'];
         e.className = attr['class'];
         
         f[e.name] = e;
  //print('    Input '+e.name);
     }
 }
}

(function(){

 // Browser Navigator

 window.navigator = {
  get userAgent(){
   return "Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.8.1.3) Gecko/20070309 Firefox/2.0.0.3";
  },
  get appVersion(){
   return "Mozilla/5.0";
  }
 };
 
 var curLocation = (new java.io.File("./")).toURL();
 
 window.__defineSetter__("location", function(url){
  var xhr = new XMLHttpRequest();
  xhr.open("GET", url);
  xhr.onreadystatechange = function(){
   curLocation = new java.net.URL( curLocation, url );
   window.document = xhr.responseXML;
   collectForms(window.document);

   var event = document.createEvent();
   event.initEvent("load");
   window.dispatchEvent( event );
  };
  xhr.send();
 });
 
 window.__defineGetter__("location", function(url){
  return {
   get protocol(){
    return curLocation.getProtocol() + ":";
   },
   get href(){
    return curLocation.toString();
   },
   toString: function(){
    return this.href;
   }
  };
 });
 
 // Timers

 var timers = [];
 
 window.setTimeout = function(fn, time){
  var num;
  return num = setInterval(function(){
   fn();
   clearInterval(num);
  }, time);
 };
 
 window.setInterval = function(fn, time){
  var num = timers.length;
  
  timers[num] = new java.lang.Thread(new java.lang.Runnable({
   run: function(){
    while (true){
     java.lang.Thread.currentThread().sleep(time);
     fn();
    }
   }
  }));
  
  timers[num].start();
 
  return num;
 };
 
 window.clearInterval = function(num){
  if ( timers[num] ) {
   timers[num].stop();
   delete timers[num];
  }
 };
 
 // Window Events
 
 var events = [{}];

 window.addEventListener = function(type, fn){
  if ( !this.uuid || this == window ) {
   this.uuid = events.length;
   events[this.uuid] = {};
  }
    
  if ( !events[this.uuid][type] )
   events[this.uuid][type] = [];
  
  if ( events[this.uuid][type].indexOf( fn ) < 0 )
   events[this.uuid][type].push( fn );
 };
 
 window.removeEventListener = function(type, fn){
    if ( !this.uuid || this == window ) {
        this.uuid = events.length;
        events[this.uuid] = {};
    }
    
    if ( !events[this.uuid][type] )
   events[this.uuid][type] = [];
   
  events[this.uuid][type] =
   events[this.uuid][type].filter(function(f){
    return f != fn;
   });
 };
 
 window.dispatchEvent = function(event){
  if ( event.type ) {
   if ( this.uuid && events[this.uuid][event.type] ) {
    var self = this;
   
    events[this.uuid][event.type].forEach(function(fn){
     fn.call( self, event );
    });
   }
   
   if ( this["on" + event.type] )
    this["on" + event.type].call( self, event );
  }
 };
 
 // DOM Document
 
 window.DOMDocument = function(file){
  this._file = file;
  var factory = Packages.javax.xml.parsers.DocumentBuilderFactory.newInstance();
  factory.setValidating(false);
  this._dom = factory.newDocumentBuilder().parse(file);
  
  if ( !obj_nodes.containsKey( this._dom ) )
   obj_nodes.put( this._dom, this );
 };
 
 DOMDocument.prototype = {
  createTextNode: function(text){
   return makeNode( this._dom.createTextNode(
    text.replace(/&/g, "&").replace(/</g, "<").replace(/>/g, ">")) );
  },
  createElement: function(name){
   return makeNode( this._dom.createElement(name.toLowerCase()) );
  },
  getElementsByTagName: function(name){
   return new DOMNodeList( this._dom.getElementsByTagName(
    name.toLowerCase()) );
  },
  getElementById: function(id){
   var elems = this._dom.getElementsByTagName("*");
   
   for ( var i = 0; i < elems.length; i++ ) {
    var elem = elems.item(i);
    if ( elem.getAttribute("id") == id )
     return makeNode(elem);
   }
   
   return null;
  },
  get body(){
   return this.getElementsByTagName("body")[0];
  },
  get documentElement(){
   return makeNode( this._dom.getDocumentElement() );
  },
  get ownerDocument(){
   return null;
  },
  addEventListener: window.addEventListener,
  removeEventListener: window.removeEventListener,
  dispatchEvent: window.dispatchEvent,
  get nodeName() {
   return "#document";
  },
  importNode: function(node, deep){
   return makeNode( this._dom.importNode(node._dom, deep) );
  },
  toString: function(){
   return "Document" + (typeof this._file == "string" ?
    ": " + this._file : "");
  },
  get innerHTML(){
   return this.documentElement.outerHTML;
  },
  
  get defaultView(){
   return {
    getComputedStyle: function(elem){
     return {
      getPropertyValue: function(prop){
       prop = prop.replace(/-(w)/g,function(m,c){
        return c.toUpperCase();
       });
       var val = elem.style[prop];
       
       if ( prop == "opacity" && val == "" )
        val = "1";
        
       return val;
      }
     };
    }
   };
  },
  
  createEvent: function(){
   return {
    type: "",
    initEvent: function(type){
     this.type = type;
    }
   };
  }
 };
 
 function getDocument(node){
  return obj_nodes.get(node);
 }
 
 // DOM NodeList
 
 window.DOMNodeList = function(list){
  this._dom = list;
  this.length = list.getLength();
  
  for ( var i = 0; i < this.length; i++ ) {
   var node = list.item(i);
   this[i] = makeNode( node );
  }
 };
 
 DOMNodeList.prototype = {
  toString: function(){
   return "[ " +
    Array.prototype.join.call( this, ", " ) + " ]";
  },
  get outerHTML(){
   return Array.prototype.map.call(
    this, function(node){return node.outerHTML;}).join('');
  }
 };
 
 // DOM Node
 
 window.DOMNode = function(node){
  this._dom = node;
 };
 
 DOMNode.prototype = {
  get nodeType(){
   return this._dom.getNodeType();
  },
  get nodeValue(){
   return this._dom.getNodeValue();
  },
  get nodeName() {
   return this._dom.getNodeName();
  },
  cloneNode: function(deep){
   return makeNode( this._dom.cloneNode(deep) );
  },
  get ownerDocument(){
   return getDocument( this._dom.ownerDocument );
  },
  get documentElement(){
   return makeNode( this._dom.documentElement );
  },
  get parentNode() {
   return makeNode( this._dom.getParentNode() );
  },
  get nextSibling() {
   return makeNode( this._dom.getNextSibling() );
  },
  get previousSibling() {
   return makeNode( this._dom.getPreviousSibling() );
  },
  toString: function(){
   return '"' + this.nodeValue + '"';
  },
  get outerHTML(){
   return this.nodeValue;
  }
 };

 // DOM Element

 window.DOMElement = function(elem){
  this._dom = elem;
  this.style = {
   get opacity(){ return this._opacity; },
   set opacity(val){ this._opacity = val + ""; }
  };
  
  // Load CSS info
  var styles = (this.getAttribute("style") || "").split(/s*;s*/);
  
  for ( var i = 0; i < styles.length; i++ ) {
   var style = styles[i].split(/s*:s*/);
   if ( style.length == 2 )
    this.style[ style[0] ] = style[1];
  }
 };
 
 DOMElement.prototype = extend( new DOMNode(), {
  get nodeName(){
   return this.tagName.toUpperCase();
  },
  get tagName(){
   return this._dom.getTagName();
  },
  toString: function(){
   return "<" + this.tagName + (this.id ? "#" + this.id : "" ) + ">";
  },
  get outerHTML(){
   var ret = "<" + this.tagName, attr = this.attributes;
   
   for ( var i in attr )
    ret += " " + i + "='" + attr[i] + "'";
    
   if ( this.childNodes.length || this.nodeName == "SCRIPT" )
    ret += ">" + this.childNodes.outerHTML + 
     "</" + this.tagName + ">";
   else
    ret += "/>";
   
   return ret;
  },
  
  get attributes(){
   var attr = {}, attrs = this._dom.getAttributes();
   
   for ( var i = 0; i < attrs.getLength(); i++ )
    attr[ attrs.item(i).nodeName ] = attrs.item(i).nodeValue;
    
   return attr;
  },
  
  get innerHTML(){
   return this.childNodes.outerHTML; 
  },
  set innerHTML(html){
   html = html.replace(/</?([A-Z]+)/g, function(m){
    return m.toLowerCase();
   });
   
   var nodes = this.ownerDocument.importNode(
    new DOMDocument( new java.io.ByteArrayInputStream(
     (new java.lang.String("<wrap>" + html + "</wrap>"))
      .getBytes("UTF8"))).documentElement, true).childNodes;
    
   while (this.firstChild)
    this.removeChild( this.firstChild );
   
   for ( var i = 0; i < nodes.length; i++ )
    this.appendChild( nodes[i] );
  },
  
  get textContent(){
   return nav(this.childNodes);
   
   function nav(nodes){
    var str = "";
    for ( var i = 0; i < nodes.length; i++ )
     if ( nodes[i].nodeType == 3 )
      str += nodes[i].nodeValue;
     else if ( nodes[i].nodeType == 1 )
      str += nav(nodes[i].childNodes);
    return str;
   }
  },
  set textContent(text){
   while (this.firstChild)
    this.removeChild( this.firstChild );
   this.appendChild( this.ownerDocument.createTextNode(text));
  },
  
  style: {},
  clientHeight: 0,
  clientWidth: 0,
  offsetHeight: 0,
  offsetWidth: 0,
  
  get disabled() {
   var val = this.getAttribute("disabled");
   return val != "false" && !!val;
  },
  set disabled(val) { return this.setAttribute("disabled",val); },
  
  get checked() {
   var val = this.getAttribute("checked");
   return val != "false" && !!val;
  },
  set checked(val) { return this.setAttribute("checked",val); },
  
  get selected() {
   if ( !this._selectDone ) {
    this._selectDone = true;
    
    if ( this.nodeName == "OPTION" && !this.parentNode.getAttribute("multiple") ) {
     var opt = this.parentNode.getElementsByTagName("option");
     
     if ( this == opt[0] ) {
      var select = true;
      
      for ( var i = 1; i < opt.length; i++ )
       if ( opt[i].selected ) {
        select = false;
        break;
       }
       
      if ( select )
       this.selected = true;
     }
    }
   }
   
   var val = this.getAttribute("selected");
   return val != "false" && !!val;
  },
  set selected(val) { return this.setAttribute("selected",val); },

  get className() { return this.getAttribute("class") || ""; },
  set className(val) {
   if (typeof val != 'string') { val = "" + val; }
   return this.setAttribute("class",
    val.replace(/(^s*|s*$)/g,""));
  },
  
  get type() { return this.getAttribute("type") || ""; },
  set type(val) { return this.setAttribute("type",val); },
  
  get value() { return this.getAttribute("value") || ""; },
  set value(val) { return this.setAttribute("value",val); },
  
  get src() { return this.getAttribute("src") || ""; },
  set src(val) { return this.setAttribute("src",val); },
  
  get id() { return this.getAttribute("id") || ""; },
  set id(val) { return this.setAttribute("id",val); },
  
  getAttribute: function(name){
   return this._dom.hasAttribute(name) ?
    new String( this._dom.getAttribute(name) ) :
    null;
  },
  setAttribute: function(name,value){
   this._dom.setAttribute(name,value);
  },
  removeAttribute: function(name){
   this._dom.removeAttribute(name);
  },
  
  get childNodes(){
   return new DOMNodeList( this._dom.getChildNodes() );
  },
  get firstChild(){
   return makeNode( this._dom.getFirstChild() );
  },
  get lastChild(){
   return makeNode( this._dom.getLastChild() );
  },
  appendChild: function(node){
   this._dom.appendChild( node._dom );
  },
  insertBefore: function(node,before){
   this._dom.insertBefore( node._dom, before ? before._dom : before );
  },
  removeChild: function(node){
   this._dom.removeChild( node._dom );
  },

  getElementsByTagName: DOMDocument.prototype.getElementsByTagName,
  
  addEventListener: window.addEventListener,
  removeEventListener: window.removeEventListener,
  dispatchEvent: window.dispatchEvent,
  
  click: function(){
   var event = document.createEvent();
   event.initEvent("click");
   this.dispatchEvent(event);
  },
  submit: function(){
   var event = document.createEvent();
   event.initEvent("submit");
   this.dispatchEvent(event);
  },
  focus: function(){
   var event = document.createEvent();
   event.initEvent("focus");
   this.dispatchEvent(event);
  },
  blur: function(){
   var event = document.createEvent();
   event.initEvent("blur");
   this.dispatchEvent(event);
  },
  get elements(){
   return this.getElementsByTagName("*");
  },
  get contentWindow(){
   return this.nodeName == "IFRAME" ? {
    document: this.contentDocument
   } : null;
  },
  get contentDocument(){
   if ( this.nodeName == "IFRAME" ) {
    if ( !this._doc )
     this._doc = new DOMDocument(
      new java.io.ByteArrayInputStream((new java.lang.String(
      "<html><head><title></title></head><body></body></html>"))
      .getBytes("UTF8")));
    return this._doc;
   } else
    return null;
  }
 });
 
 // Helper method for extending one object with another
 
 function extend(a,b) {
  for ( var i in b ) {
   var g = b.__lookupGetter__(i), s = b.__lookupSetter__(i);
   
   if ( g || s ) {
    if ( g )
     a.__defineGetter__(i, g);
    if ( s )
     a.__defineSetter__(i, s);
   } else
    a[i] = b[i];
  }
  return a;
 }
 
 // Helper method for generating the right
 // DOM objects based upon the type
 
 var obj_nodes = new java.util.HashMap();
 
 function makeNode(node){
  if ( node ) {
   if ( !obj_nodes.containsKey( node ) )
    obj_nodes.put( node, node.getNodeType() == 
     Packages.org.w3c.dom.Node.ELEMENT_NODE ?
      new DOMElement( node ) : new DOMNode( node ) );
   
   return obj_nodes.get(node);
  } else
   return null;
 }
 
 // XMLHttpRequest
 // Originally implemented by Yehuda Katz

 window.XMLHttpRequest = function(){
  this.headers = {};
  this.responseHeaders = {};
 };
 
 XMLHttpRequest.prototype = {
  open: function(method, url, async, user, password){ 
   this.readyState = 1;
   if (async)
    this.async = true;
   this.method = method || "GET";
   this.url = url;
   this.onreadystatechange();
  },
  setRequestHeader: function(header, value){
   this.headers[header] = value;
  },
  getResponseHeader: function(header){ },
  send: function(data){
   var self = this;
   
   function makeRequest(){
    var url = new java.net.URL(curLocation, self.url);
    
    if ( url.getProtocol() == "file" ) {
     if ( self.method == "PUT" ) {
      var out = new java.io.FileWriter( 
        new java.io.File( new java.net.URI( url.toString() ) ) ),
       text = new java.lang.String( data || "" );
      
      out.write( text, 0, text.length() );
      out.flush();
      out.close();
     } else if ( self.method == "DELETE" ) {
      var file = new java.io.File( new java.net.URI( url.toString() ) );
      file["delete"]();
     } else {
      var connection = url.openConnection();
      connection.connect();
      handleResponse();
     }
    } else { 
     var connection = url.openConnection();
     
     connection.setRequestMethod( self.method );
     
     // Add headers to Java connection
     for (var header in self.headers)
      connection.addRequestProperty(header, self.headers[header]);
    
     connection.connect();
     
     // Stick the response headers into responseHeaders
     for (var i = 0; ; i++) { 
      var headerName = connection.getHeaderFieldKey(i); 
      var headerValue = connection.getHeaderField(i); 
      if (!headerName && !headerValue) break; 
      if (headerName)
       self.responseHeaders[headerName] = headerValue;
     }
     
     handleResponse();
    }
    
    function handleResponse(){
     self.readyState = 4;
     self.status = parseInt(connection.responseCode) || undefined;
     self.statusText = connection.responseMessage || "";
     
     var stream = new java.io.InputStreamReader(connection.getInputStream()),
      buffer = new java.io.BufferedReader(stream), line;
     
     while ((line = buffer.readLine()) != null)
      self.responseText += line;
      
     self.responseXML = null;
     
     if ( self.responseText.match(/^s*</) ) {
      //try {
       self.responseXML = new DOMDocument(
        new java.io.ByteArrayInputStream(
         (new java.lang.String(
          self.responseText)).getBytes("UTF8")));
      //} catch(e) {
      //}
     }
    }
    
    self.onreadystatechange();
   }

   if (this.async)
    (new java.lang.Thread(new java.lang.Runnable({
     run: makeRequest
    }))).start();
   else
    makeRequest();
  },
  abort: function(){},
  onreadystatechange: function(){},
  getResponseHeader: function(header){
   if (this.readyState < 3)
    throw new Error("INVALID_STATE_ERR");
   else {
    var returnedHeaders = [];
    for (var rHeader in this.responseHeaders) {
     if (rHeader.match(new Regexp(header, "i")))
      returnedHeaders.push(this.responseHeaders[rHeader]);
    }
   
    if (returnedHeaders.length)
     return returnedHeaders.join(", ");
   }
   
   return null;
  },
  getAllResponseHeaders: function(header){
   if (this.readyState < 3)
    throw new Error("INVALID_STATE_ERR");
   else {
    var returnedHeaders = [];
    
    for (var header in this.responseHeaders)
     returnedHeaders.push( header + ": " + this.responseHeaders[header] );
    
    return returnedHeaders.join("rn");
   }
  },
  async: true,
  readyState: 0,
  responseText: "",
  status: 0
 };
})();

1 Comment | Software | Tagged: , , , | Permalink
Posted by digulla

UPCScan 0.7: Where is my stuff?

16. November, 2008

UPCScan 0.7 is released. New features:

  • UPCScan can now find music CDs
  • If UPCScan can’t find something on Amazon, it will still create an entry which you can then edit to fill in the details.
  • Entries can be deleted.
  • I’ve added lending information so you can quickly figure out who your new “ex-friends” should be.
  • I’m working on a series/issue information system to make it more simple to complete your collection. With this version, you’ll need to edit the database directly to add series/issue information but the user interface can already display this data.
  • I’m working on a feature to create an OpenOffice document with the locations. This would allow you to print this out and then scan the locations in as you scan your collection to tell UPCScan under which location to file the items. If you can’t wait, then you can use the barcode.py script to generate PNG images with barcodes which you can import in OpenOffice to achieve the same effect.

Download: upcscan-0.7.tar.gz (26,921 Bytes, MD5)

1 Comment | Software | Tagged: , , | Permalink
Posted by digulla

Testing the Impossible: User Dialogs

11. November, 2008

How do you test a user dialog like “Do you really want to quit?”

This code usually looks like this:

    public void quit () {
        if (!MessageDialog.ask (getShell(),
            "Really quit?",
            "Do you really want to quit?"
        ))
            return;

        ... quit ...
    }

The solution is simple:

    public void quit () {
        if (askToQuit ())
            return;

        ... quit ...
    }

    /** For tests */
    protected boolean askToQuit () {
        ... ask your question here ...
    }

In test cases, you can now extend the class, and override askToQuit:

    public boolean askToQuitWasCalled = false;
    public boolean askToQuitResult = true;

    protected boolean askToQuit () {
        askToQuitWasCalled = true;
        return askToQuitResult;
    }

Now, you can find out if the question would be asked and you can verify that the code behaves correctly depending on the answer. Tests that just want to quit won’t need to do anything special to get the desired behavior.

The same applies to more complex dialogs: Refactor them to put their data into an intermediate structure which you can mock during the tests. That means to copy the data if the dialog is a black box but that’s a small price to be paid for being able to test modal user dialogs.

Lesson: You don’t want to test the dialog, you want to test whether it is opened at the right place, under the right circumstances and if the result is processes correctly.

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Posted by digulla

I Have Nothing to Hide … I Think

10. November, 2008

So it has happened again. Someone put a nice web site online and when it came to pick and chose between security and comfort, guess who won. Alas, those who do as you shouldn’t still server as a bad example. What has happened?

DHL, a German parcel delivery service, offers a web site where you can track where your brand new gadget is now so you can guess how long it will take until you rip the wrapping off it. That good.

Not so good is that all customers of DHL get the same default password.

Bad is that DHL reuses the tracking numbers after roughly six months (depending on the amount of parcels that go through the system; if there are less, you can look further into the past).

Really bad is that part of DHL’s tracking number of fixed. It’s based on the DHL customer number. That’s not you, this “customer” is the guy or company you ordered from (DHL renders a service for them).

So this leaves us with a convenient way to check who else has ordered anything from those that shop.

Now imagine you ordered something innocent … oh, maybe porn or “adult toys” or something from company B which is the arch enemy of company A which incidentally pays your wage. All of a sudden, a couple of innocent bits of information have turned ugly.

Whenever you put something out to the world, step away for a few moments from your dreams how much good someone could do with your service and think how much bad someone could do with it. And if you can’t think of anything, you should be very, very worried.

Leave a Comment » | Philosophy | Tagged: , | Permalink
Posted by digulla

Multi-line String Literals in Java

30. October, 2008

You want multi-line string literals in Java which work in Java 1.4 and up? Can’t be done, you say?

Sven Efftinge found a way.

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Posted by digulla

Compile VMware tools on openSUSE 10.3

27. October, 2008

I just tried to install the VMware tools on openSUSE 10.3 (Linux kernel 2.6.22.18) so the virtual machine would survive more than 10 days on an ESX server and failed. If you have the same problem, the solution is here.

Errors you’ll see during the installation otherwise:

The directory of kernel headers (version @@VMWARE@@ UTS_RELEASE) does not match your running kernel (version 2.6.22.18-0.2-default). Even if the module were to compile successfully, it would not load into the running kernel.

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Posted by digulla

Failure is not an Option

22. October, 2008

Everyone loves war stories. Here is one of mine. I need a special diet, especially bread. So one Friday evening, I was taking the train home after buying a couple of custom made loafs of bread. In Dübendorf, I left the train and walked home.

About halfway home, I noticed that I had my head, my arms, my bag … but not my bread! ARGH! Stupid, stupid, stupid! I knew I should have stuffed them in my rucksack but didn’t because it was so full and … yeah … okay. My baker needs three days to make these breads so that meant about a week without any for me.

Arriving home, an idea struck me and I fired up the VBZ online service to find out where the train was and when the driver would make the next break. A few moments later, the SBB Train Police got a really strange call by me: “I need my bread. It’s in this train and can you please, please ask the driver to check if the white plastic bag with the bread is still there?”

The woman on the other end was surprised and promised to call me back.

Ten minutes can be sooo long.

From the timetable, I knew that my train would probably come through my town in about twenty minutes when I got the call. Yes, they found it and the driver would take the plastic bag into his cabin and she told me where to wait on the platform so he could hand it over.

Try train was on time (as usual), the driver handed me my bag (and it really was mine and all the bread was still there) and I was really relieved. After thanking him, I went home to have my dinner. Thanks to the SBB train police, a train driver and an unknown person who put my bread in the overhead compartment when I left it behind, I didn’t go hungry that weekend.

Lesson: If all seems lost, take a step back, do something else and you might have the idea which will save the day.

Train related joke: The SBB (Schweizer Bundesbahn – Swiss federation train company) and the German Bundesbahn (the counterpart of the SBB in Germany) wanted to save some money and decided to buy the same information system to inform about arriving trains on the platform. After a longer evaluation, the plan was dropped. The SBB needed signs which said “Train is 1, 2, 3, 4, 5 minutes late” and the German Bundesbahn needed “Train is half an hour, 1 hour, 2 hours, 3 hours, 4 hours, Train Cancelled.”

Leave a Comment » | Fun | Tagged: | Permalink
Posted by digulla

So… You want your code to be maintainable.

14. October, 2008

A great post if you’re interested in TDD or testing in general: So… You want your code to be maintainable. by Uncle Bob. Thanks, Bob!

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Posted by digulla

Good Games for the PS3

11. October, 2008

I’ve recently upgraded to a PlayStation 3. I kept my old PS2, though, since the new PS3 can’t emulate the PS2. I wonder why that is … maybe it’s because Sony is still selling so many PS2’s? Ah, rumors 🙂 Easy to create and hard to kill.

So what good games are there? Here is my list:

  • Burnout Paradise City
  • PixelJunk Eden
  • Ratchet & Clank – Tools of Destruction
  • Flow

Burnout Paradise City

Mindless street racing with a high adrenaline level. Ideal to waste a couple of minutes or an hour. Great graphics, no blood, no violence (it’s more like auto scooter) and nice ideas like smashing ads or the super jumps. If you don’t like some events (haven’t managed to win a single race, yet. I excel at kicking other cars off the street), you can simply ignore them and still complete enough of the game to have fun.

PixelJunk Eden

A definitive feel of Tarzan or Spiderman when you want to relax a bit. Simple, fitting graphics, no violence, no agression. All that and at the price it’s a steal.

Ratchet & Clank – Tools of Destruction

My favorite jump’n’run. Lots of insane weapons, Ratchet’s ears look great on the PS3, the story has more depth than usual; not sure I like the depressive realization at the end, though. Judge for yourself.

Flow

Like Eden, it’s a brand new kind of game. One of a kind. I play that when I want to come down from all the stress in my life. Go get it!

Bad games

I’ve got a couple of other games. First, we have the Orange Box with Half Life 2, two of the extra episodes, Portal and Team Fortress. I liked the puzzles in Portal. That games was much too short. I didn’t like Half Life 2 much and I hate the episodes. The story was great, the levels gigantic and intelligent. You could almost always find a way around without getting killed. But the handling … Freeman feels like a block of wood when you move him through the levels: You’ll get stuck all the time at hand rails and stuff like that. Sometimes, he’ll be able to jump on something, sometimes not. Sometimes, he’ll stay on top of a barrel, sometimes not. This sucks. And then those stupid zombie levels. Yeah, I’m stuck in the elevator scene in the first episode. Got killed five times in the dark and now, the games goes where it belongs: The trash.

Resistance – Fall of Man. I like the other games by Insomniac and I like this one, too. It’s just too violent for my taste. I like shooting pixels or push empty cars off the street or zoom down a highway at break-neck speed. I don’t like shooting at people. I finished the game but it left me asking: Is that all? Running around, shooting people, blow up stuff? Is that the result of many years of game evolution? Better graphics?

Uncharted: Drake’s Fortune. Oh well. Okay, the levels look great. When you scale the wall of the castle, there is a sense of vertigo. It’s breath taking. The jeep escape is a lot of fun. Smart story (mostly). The game character moves smart. You press a button and he takes cover. He’s smart, not a dead puppet like Freeman. He moves as if he was real. Again the violence cooled me off quickly. Too much killing, not enough puzzles.

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Posted by digulla

Enthought Traits

9. October, 2008

I’m always looking for more simple ways to build applications. Let’s face it, it’s 2008 and after roughly 50 years, writing something that collects a few bits of data and presents them in a nice way is still several days of work. And that’s without Undo/Redo, a way to persist the data, a way to evolve the storage format, etc.

Python was always promising and with the tkinter module, they set a rather high watermark on how you easily could build UIs … alas Tk is not the most powerful UI framework out there and … well … let’s just leave it at that.

With Traits, we have a new contender and I have to admit that I like it … a lot. The traits framework solves a lot of the standard issues out of the box while leaving all the hooks and bolts available between a very thin polish so you can still get at them when you have to.

For example, you have a list of persons and you want to assign each person a gender. Here is the model:

class Gender(HasTraits):
    name = Str
    
    def __repr__(self):
        return 'Gender %s' % self.name

class Person(HasTraits):
    name = Str
    gender = Instance(Gender)
    
    def __repr__(self):
        return 'Person %s' % self.name

class Model(HasTraits):
    genderList = List(Gender)
    persons = List(Person)

Here is how you use this model:

female = Gender(name='Female')
male = Gender(name='Male')
undefined = Gender(name='Undefined')

aMale = Person(name='a male', gender=male)
aFemale = Person(name='a female', gender=female)

model = Model()
model.genderList.append(female)
model.genderList.append(male)
model.genderList.append(undefined)
model.persons.append(aFemale)
model.persons.append(aMale)

Nothing fancy so far. Unlike the rest of Python, with Traits, you can make sure that an attribute of an instance has the correct type. For example, “aMale.gender = aFemale” would throw an exception in the assignment.

The nice stuff is that the UI components honor the information you use to build your model. So if you want to show a tree with all persons and genders, you use code like this:

class Model(HasTraits):
    genderList = List(Gender)
    persons = List(Person)
    tree = Property
    
    def _get_tree(self):
        return self

class ModelView(View):
    def __init__(self):
        super(ModelView, self).__init__(
            Item('tree',
                editor=TreeEditor(
                    nodes = [
                       TreeNode(node_for = [ Model ],
                           children = 'persons',
                           label = '=Persons',
                           view = View(),
                       ),
                       TreeNode(node_for = [ Person ],
                           children = '',
                           label = 'name',
                           view = View(
                               Item('name'),
                               Item('gender',
                                  editor=EnumEditor(values=genderList,)
                               ),
                           ),
                       ),
                       TreeNode(node_for = [ Model ],
                           children = 'genderList',
                           label = '=Persons by Gender',
                           view = View(),
                       ),
                       TreeNode(node_for = [ Gender ],
                           children = '',
                           label = 'name',
                           view = View(),
                       ),
                    ],
                ),
            ),
            Item('genderList', style='custom'),
            title = 'Tree Test',
            resizable = True,
            width = .5,
            height = .5,
        )

model.configure_traits(view=ModelView())

First of all, I needed to add a property “tree” to my “Model” class. This is a calculated field which just returns “self” and I need this to be able to reference it in my tree editor. The tree editor defines nodes by defining their properties. So a “Model” node has “persons” and “genderList” as children. The tree view is smart enough to figure out that these are in fact lists of elements and it will try to turn each element into a node if it can find a definition for it.

That’s it. Everything else has already been defined in your model and what would be the point in doing that again?

But there is more. With just a few more lines of code, we can get a list of all persons from a Gender instance and with just a single change in the tree view, we can see them in the view. If you select a person and change its name, all nodes in the tree will update. Without any additional wiring. Sounds too good to be true?

First, we must be able to find all persons with a certain sex in Gender. To do that, we add a property which gives us access to the model and then query the model for all persons, filter this list by gender and that’s it. Sounds complex? Have a look:

class Gender(HasTraits):
    name = Str
    persons = Property
    
    def _get_persons(self):
        return [p for p in self.model.persons
                if p.gender == self]

But how do I define the attribute “model” in Gender? This is a hen-and-egg problem. Gender references Model and vice versa. Python to the rescue. Add this line after the definition of Model:

Gender.model = Instance(Model)

That’s it. Now we need to assign this new field in Gender. We could do this manually but Traits offers a much better way: You can listen for changes on genderList!

    def _genderList_items_changed(self, new):
        for child in new.added:
            child.model = self

This code will be executed for every change to the list. I walk over the list of new children and assign “model”.

Does that work? Let’s check: Append this line at the end of the file:

assert male.persons == [aMale], male.persons

And the icing of the cake: The tree. Just change the argument “children=”” to “children = ‘persons'” in the TreeNode for Gender. Run and enjoy!

One last polish: The editor for genders looks a bit ugly. To suppress the persons list, add this to the Gender class:

    traits_view = View(
        Item('name')
    )

There is one minor issue: You can’t assign a type to the property “persons” in Gender. If you do, you’ll get strange exceptions and bugs. Other than that, this is probably the most simple way to build a tree of objects in your model that I’ve seen so far.

To make things easier for you to try, here is the complete source again in one big block. You can download the Enthought Python Distribution which contains all and everything on the Enthought website.

from enthought.traits.api import 
        HasTraits, Str, Instance, List, Property, This

from enthought.traits.ui.api import 
        TreeEditor, TreeNode, View, Item, EnumEditor

class Gender(HasTraits):
    name = Str
    # Bug1: This works
    persons = Property
    # This corrupts the UI:
    # wx._core.PyDeadObjectError: The C++ part of the ScrolledPanel object has been 
    # deleted, attribute access no longer allowed.
    #persons = Property(List)
    
    traits_view = View(
        Item('name')
    )
    
    def _get_persons(self):
        return [p for p in self.model.persons if p.gender == self]
    
    def __repr__(self):
        return 'Gender %s' % self.name

class Person(HasTraits):
    name = Str
    gender = Instance(Gender)
    
    def __repr__(self):
        return 'Person %s' % self.name

# Bug1: This doesn't work; you'll get ForwardProperty instead of a list when
# you access the property "persons"!
#Gender.persons = Property(fget=Gender._get_persons, trait=List(Person),)
# Same
#Gender.persons = Property(trait=List(Person),)
# Same
#Gender.persons = Property()
# Same, except it's now a TraitFactory
#Gender.persons = Property

class Model(HasTraits):
    genderList = List(Gender)
    persons = List(Person)
    tree = Property
    
    def _get_tree(self):
        return self
    
    def _genderList_items_changed(self, new):
        for child in new.added:
            child.model = self

Person.model = Instance(Model)
Gender.model = Instance(Model)

female = Gender(name='Female')
male = Gender(name='Male')
undefined = Gender(name='Undefined')

aMale = Person(name='a male', gender=male)
aFemale = Person(name='a female', gender=female)

model = Model()
model.genderList.append(female)
model.genderList.append(male)
model.genderList.append(undefined)
model.persons.append(aFemale)
model.persons.append(aMale)

assert male.persons == [aMale], male.persons

# This must be extenal because it references "Model"
# Usually, you would define this in the class to edit
# as a class field called "traits_view".
class ModelView(View):
    def __init__(self):
        super(ModelView, self).__init__(
            Item('tree',
                editor=TreeEditor(
                    nodes = [
                       TreeNode(node_for = [ Model ],
                           children = 'persons',
                           label = '=Persons',
                           view = View(),
                       ),
                       TreeNode(node_for = [ Person ],
                           children = '',
                           label = 'name',
                           view = View(
                               Item('name'),
                               Item('gender',
                                  editor=EnumEditor(
                                      values=model.genderList,
                                  )
                               ),
                           ),
                       ),
                       TreeNode(node_for = [ Model ],
                           children = 'genderList',
                           label = '=Persons by Gender',
                           view = View(),
                       ),
                       TreeNode(node_for = [ Gender ],
                           children = 'persons',
                           label = 'name',
                           view = View(),
                       ),
                    ],
                ),
            ),
            Item('genderList', style='custom'),
            title = 'Tree Test',
            resizable = True,
            width = .5,
            height = .5,
        )

model.configure_traits(view=ModelView())

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Posted by digulla

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