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Microsoft: Developers Are So Yesterday

Posted: August 31, 2007, 10:18pm CEST by Rob Williams

Perfect reprise for the biggest Ape in computing: here. If you haven't seen the YouTube classic Developers, Developers, Developers, spin that first.

Sending a file on the client disk using Applet (HTTP Protocol)

Posted: August 31, 2007, 7:39pm CEST by Hazem Ahmed Saleh

One of the problems I have faced during development is to make an applet that can upload the client files on the server side using HTTP protocol.
After I have done the solution, I would liked to share the main code idea with you.
To realize the high level world, we should make the following :-
1. On the client side : An applet that can send the file over Http connection.
2. On the server side : A servlet that receives the file and save on the server disk.

1. On the client side :
The core method of the applet code which upload the file to the server is as follows:-


  /**

   * This method upload the file to the server ...

   * @param fullFileName :

   *            The file to be uploaded.           

   * @throws IOException

   */

  public void uploadFile(String fullFileName) throws IOException {



    File file = new File(fullFileName);



    FileInputStream fileInputStream = new FileInputStream(file);

    byte[] buffer = new byte[fileInputStream.available()];



    int bytesRead = 0;



    //Open a connection to the resource servlet on the server ...

    URL servleturl = new URL("http://localhost:9080/WebResource/ResourceServlet");

    URLConnection servletConnection = servleturl.openConnection();

    servletConnection.setDoInput(true);

    servletConnection.setDoOutput(true);

    servletConnection.setUseCaches(false);

    servletConnection.setDefaultUseCaches(false);



    DataOutputStream out = new DataOutputStream(servletConnection

        .getOutputStream());



    //Write the streams of bytes to the output stream ...

    while ((bytesRead = fileInputStream.read(buffer)) > -1) {

      out.write(buffer, 0, bytesRead);

    }



    out.flush();

    out.close();

    fileInputStream.close();

    

    //I have to write these 2 lines to successfully uploads the file ...

    DataInputStream inputFromClient = new DataInputStream(servletConnection

        .getInputStream());

    inputFromClient.close();

  }

2. On the server side :
I have made a resource servlet which dumps the client inputStream to the server disk.
Here is the servlet code :-


/**

 * This is the resource servlet that receives the file uploaded from the applet ...

 * @author hazems

 */



public class ResourceServlet extends HttpServlet {  

  

  final String seperator = ".";

  

  /**

   * This method generates a unique filename using the sessionID

   * @param sessionID

   * @return the generated fileName ...

   */

  protected String getGeneratedFileName(String sessionID) {

    return "FILE" + seperator + sessionID + seperator

        + System.currentTimeMillis();

  }

  

  protected synchronized void doGet(HttpServletRequest request,

      HttpServletResponse response) throws ServletException, IOException {

    ServletContext sc = this.getServletContext();



    //Save the file on the server and seu its name to the generated name ...

    String fileName = getGeneratedFileName(request.getSession().getId());



    String path = sc.getRealPath(File.separator) + fileName;



    //Dump the inputStream to the server disk ...

    File file = new File(path);

    FileOutputStream toFile = new FileOutputStream(file);

    DataInputStream fromClient = new DataInputStream(request

        .getInputStream());



    byte[] buffer = new byte[1024];

    int retval = 0;

    while ((retval = fromClient.read(buffer)) > -1) {

      toFile.write(buffer, 0, retval);

    }

    toFile.flush();

    toFile.close();

    fromClient.close();



    System.err

        .println("ResourceServlet called successfully and the file saved at : "

            + path);

  }



  protected void doPost(HttpServletRequest request, HttpServletResponse response)

      throws ServletException, IOException {

    doGet(request, response);

  }



}

This is all about :).

TopCoder UML: Like Top Chef, Hold the Mayo

Posted: August 31, 2007, 5:30pm CEST by Rob Williams

TopCoder says on their site that they were named to Inc. Magazines list of fastest growing companies. What seems to be growing alongside their company is their hubris. They wanted to find a UML tool to use, but couldn't so what do you think they did? They built one, Pal. Step aside. Here it is. (Another early sign of hubris here: they only implemented some of the diagram types, and in a move that defies reason, they did sequence diagrams, but did not add the ability to see the sequence as a collaboration.. but folks, omission is one of the sharpest forms of definition.)
Now, having long flown the flag that the world needed a really good UML tool, I was of course interested. I downloaded and followed the instructions, and what do you know, it doesn't work. No icon appears, and running run.sh gets nothing. Must be because I am on the mac. Announcement, ye of increasing heft: TONS of devs are on macs now. After reading a huge torrent of hyperbole that makes TC seem like the development equivalent of cold fusion (not the templating tinkertoy, the dixie cup sun), it is laughable to push through the first turnstile into an experience that is so fraught with the usual potholes. Here's a clue folks: if yer fusion has platform requirements, get one of the Herculeans to add a short list to the download page, it will make y'all seem a bit less like just another gangway attraction in the Barnumian Universe.

Writing SQL the OO Way II

Posted: August 31, 2007, 5:03pm CEST by Solomon Duskis

I didn't include code last entry on this subject. Basically, I wanted a really simple abstraction to a select statement so I can:

produce strings rather than technology dependent results
easily combine select clauses to create sub-selects, INSERT-INTO-SELECT-FROM or union queries
create a common base-line query to be used for a given DAO
add from/where/order by/select clauses in a logical unit
flexibility to write SQL, HQL or JPA-QL
flexibility to add what I need when I need it (for example, I don't need "Group By" clauses now, but I can add it really easily if and when I'll need them)

All of this was written for situations where I have the same basic query over and over again, with slight variations, mostly driven by different user options. It's very similar to what you can do with Hibernate's Criteria object, except I'm dealing with a very thin abstraction over a string rather than a new paradigm.

With out further ado, here's the code:

package builder;

import java.util.*;

import org.springframework.util.CollectionUtils;
import org.springframework.util.StringUtils;

/**
 * This class represents a select statement.
 *
 * @author sduskis
 */
public class SearchQuery {

    private List select = new ArrayList();
    private List from = new ArrayList();
    private List where = new ArrayList();
    private List order = new ArrayList();
    private Map parameters = new HashMap();

    public String toString() {
        StringBuffer selectString = new StringBuffer();
        addSqlString("SELECT ", this.select, ",nt", selectString);
        addSqlString("FROM ", this.from, ",nt", selectString);
        addSqlString("WHERE ", this.where, "ntand ", selectString);
        addSqlString("ORDER BY ", this.order, ",nt", selectString);
        return selectString.toString();
    }

    private StringBuffer addSqlString(String prefix, List list, String delimiter, StringBuffer s) {
        if (CollectionUtils.isEmpty(list))
            return s;
        if (s.length() != 0)
            s.append("n");
        return s.append(prefix).append(StringUtils.collectionToDelimitedString(list, delimiter));
    }

    public SearchQuery select(String s) {
        return add(select, s);
    }

    public SearchQuery from(String s) {
        return add(from, s);
    }

    /** add joins to an existing "table */
    public SearchQuery appendFrom(String appendStr, int location) {
        String fromStr = from.get(location).toString();
        fromStr += appendStr;
        from.set(location, fromStr);
        return this;
    }

    public SearchQuery where(String s) {
        return add(where, s);
    }

    public SearchQuery orderBy(String s) {
        return add(order, s);
    }

    public SearchQuery parameter(String key, Object param) {
        parameters.put(key, param);
        return this;
    }

    private SearchQuery add(List l, Object o) {
        if (o != null)
            l.add(o);
        return this;
    }

    ... GETTERS ...
}

Java 7 - Self-types

Posted: August 31, 2007, 4:37pm CEST by Stephen Colebourne
I just screamed at Java again. This time my ire has been raised by the lack of self-types in the language.
Self-types
So what is a self-type. Well, I could point you at some links, but I'll try and have a go at defining it myself...

A self-type is a special type that always refers to the current class. Its used mostly with generics, and if you've never needed it then you won't understand what a pain it is that it isn't in Java.

Here's my problem to help explain the issue. Consider two immutable classes - ZonedDate and LocalDate - both declaring effectively the same method:
```
 public final class ZonedDate {
   ZonedDate withYear(int year) { ... }
 }
 public final class LocalDate {
   LocalDate withYear(int year) { ... }
 }
```
The implementations only differ in the return type. This is essential for immutable classes, as you need the returned instance to be the same type as the original in order to call other methods (like withMonthOfYear).

Now consider that both methods actually contain the same code, and I want to abstract that out into a shared abstract superclass. This is where we get stuck:
```
 public abstract class BaseDate {
   BaseDate withYear(int year) { ... }
 }
 public final class ZonedDate extends BaseDate {
   // withYear removed as now in superclass, or is it?
 }
 public final class LocalDate extends BaseDate {
   // withYear removed as now in superclass, or is it?
 }
```
The problem is that we've changed the effect of the method as far as ZonedDate and LocalDate are concerned, because they no longer return the correct type, but now return the type of the superclass.

One solution is to override the abstract implementation in the subclass, just to get the correct return type (via covariance):
```
 public abstract class BaseDate {
   BaseDate withYear(int year) { ... }
 }
 public final class ZonedDate extends BaseDate {
   ZonedDate withYear(int year) {
     return (ZonedDate) super.withYear(year);
   }
 }
 public final class LocalDate extends BaseDate {
   LocalDate withYear(int year) {
     return (LocalDate) super.withYear(year);
   }
 }
```
What a mess. Imagine doing that for many methods on many subclasses. Its a large amount of pointless boilerplate code for no good reason. What we really want is self-types, with a syntax such as <this>:
```
 public abstract class BaseDate {
   <this> withYear(int year);
 }
 public final class ZonedDate extends BaseDate {
   // withYear removed as now correctly in superclass
 }
 public final class LocalDate extends BaseDate {
   // withYear removed as now correctly in superclass
 }
```
The simple device of the self-type means that the withYear method will now appear to have the correct return type in each of the subclasses - LocalDate in LocalDate, ZonedDate in ZonedDate and so on. And without reams of dubious boilerplate.
Summary
Self-types are a necessary companion for abstract classes where the subclass is to be immutable (and there are probably other good uses too...).

Opinions welcome as always!

Property ListCellRenderer for JLists

Posted: August 31, 2007, 3:53pm CEST by Wim Deblauwe

A lot of times you need to create a custom ListCellRenderer, just to display a property of the class you are showing in your JList. Normally you would write something like this:

	private static class MyObjectListCellRenderer extends DefaultListCellRenderer
	{
		@Override
		public Component getListCellRendererComponent( JList list, Object value, int index, boolean isSelected, boolean cellHasFocus )
		{
			JLabel label = (JLabel)super.getListCellRendererComponent( list, value, index, isSelected, cellHasFocus );

			label.setText( ((MyObject)value).getName() );
			return label;
		}
	}

To avoid having to write this, I create a PropertyListCellRenderer (inspired by GlazedList's TableFormat method) that avoids that you need to subclass, you can just create one like this:

ListCellRenderer renderer = new PropertyListCellRenderer( "name", 
                                                          MyObject.class );
myJList.setCellRenderer( renderer );

This is the code for the PropertyListCellRenderer:

package com.jroller.fester.swing;

import org.apache.log4j.Logger;

import javax.swing.*;
import java.awt.*;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 *
 */
public class PropertyListCellRenderer extends DefaultListCellRenderer
{
	private static final Logger logger = Logger.getLogger( PropertyListCellRenderer.class );

	private final String m_propertyName;
	private final Class m_clazz;

	/**
	 * @param propertyName the name of the property you want to be shown in the list
	 * @param clazz		the class of the objects that are in the list model
	 */
	public PropertyListCellRenderer( String propertyName, Class clazz )
	{
		m_propertyName = propertyName;
		m_clazz = clazz;
	}

	@Override
	public Component getListCellRendererComponent( JList list, Object value, int index, boolean isSelected, boolean cellHasFocus )
	{
		JLabel label = (JLabel)super.getListCellRendererComponent( list, value, index, isSelected, cellHasFocus );

		try
		{
			String methodName = "get" + m_propertyName.substring( 0, 1 ).toUpperCase() + m_propertyName.substring( 1 );
			Method m = m_clazz.getMethod( methodName );
			if (m == null)
			{
				throw new IllegalArgumentException( "Method '" + methodName + "' could not be found" );
			}
			if (m_clazz.isAssignableFrom( value.getClass() ))
			{
				String text = (String)m.invoke( value );
				label.setText( text );
			}
			else
			{
				throw new IllegalArgumentException( "The value in the list is not of class " + m_clazz.getName() + ", but class " + value.getClass().getName() );
			}
		}
		catch (NoSuchMethodException e)
		{
			logger.error( e.getMessage(), e );
		}
		catch (IllegalAccessException e)
		{
			logger.error( e.getMessage(), e );
		}
		catch (InvocationTargetException e)
		{
			logger.error( e.getMessage(), e );
		}
		return label;
	}

}

It is pretty straight forward and using standard Java reflection techniques.

A tiny issue when using properties file in an ant property definiton

Posted: August 31, 2007, 2:32pm CEST by Hasan Turksoy

today i lost some time while struggling with a tiny(possibly buggy) case... my case is: put a property in a properties file and use it from an ant build file :)
in fact, it's so easy.. but a tiny issue caused to lose some time of mine... dropping it may help others...

suppose we have property file like this;


modul.properties


prop1=val1

prop2=val2

myJarDir=gisjars

...

above property file defines a property, myJarDir, to hold the directory name of may jars...

second, we have an ant build.xml file which includes a task to create a directory with "myJarDir" property's value;


build.xml


<project name="sampleAntProject" basedir="." default="make-jar-dir">



 <!-- my property files will be in this directory -->

 <property name="prop-file-dir" location="config" />

 

 <property name="webcontent-dir" location="WebContent" />

 

 <!-- this is the property to hold the full directory name to put jars -->

 <property name="mylib-dir" value="${webcontent-dir}/${myJarDir}" />

 

 <!-- load my property file into ant -->

 <loadproperties srcfile="${prop-file-dir}/module.properties" />



 <!-- create a directory(with "mylib-dir" value) -->

 <target name="make-jar-dir">

  <mkdir dir="${mylib-dir}" />

 </target>

 

</project>

now, when you run the task you will see that; it will create a folder as "WebContent${myJarDir}" not our expected "WebContentgisjars" folder...

problem is; ant can not see the property from my property file if i load that property file after its usage in another property. To get the correct result, we should load our property file before its usage(above the "mylib-dir" property).

working build.xml should be written like below;


build.xml


<project name="sampleAntProject" ................>



 ..................

 <!-- this part is same as above -->

 ..................

 

 <!-- LOAD PROPERTIES FILE BEFORE THAT PROPERTY USED! -->

 <loadproperties srcfile="${prop-file-dir}/module.properties" />

 

 <!-- USE FILE PROPERTIES AFTER LOADED -->

 <property name="mylib-dir" value="${webcontent-dir}/${myJarDir}" />

</project>

it's interesting that; if i use "${webcontent-dir}/${myJarDir}" directly at mkdir task, it's working as normal.. This error occurs only if i put "${webcontent-dir}/${myJarDir}" value into another property(mylib-dir) before the loadproperties task and use that property at my mkdir task.

i've googled and looked at ant docs but can not see any information about definition order of properties.. if anyone see a doc explaining property definition order of ant, i'll be glad to read it..

Yahoo Pipes saving Us From Mobile Fragmentation

Posted: August 31, 2007, 1:40pm CEST by Fred Grott

I am tired of certain handset OEMs hiding bug dat about sdks and JVMs behind walls that I cannot access. Thus, this weekend I will be setting up page scrappers to create feeds of certain j2me developer forums since j2me developers are usually the first ones to document the bugs and than feed that into a specially created Yahoo Pipe setup.

It will be imperfect as the feed data will be dynamic and need reading each week to get value but I am not waiting for the rest of the damn handset OEMs to finally determine that they need a common bug database for their JVM implementations.
How was Java named?

Posted: August 31, 2007, 12:48pm CEST by Navaneetha krishnan

Begin forwarded message:
From: James Gosling

Date: August 24, 2007 8:16:58 PM PDT

To: Jonathan Schwartz

Subject: How was Java named?

The story goes like this:

We needed a name. We had been using "oak" (which was selected
essentially randomly by me), and while the team had grown attached to
it, the trademark lawyers ruled it out. We had lots of email debates
about names, but nothing got resolved. We ended up in the awkward
position where the #1 thing stopping us from shipping was the name.

Our marketing lead knew someone who was a "naming consultant"
(I don't remember his name, but he was great). We could neither afford
the price nor the time of a conventional product naming process. He
agreed to do something rather odd, but effective and quick: he acted as
a facilitator at a meeting where about a dozen of us locked ourselves
in a room for an afternoon. He started asking us questions like "How
does this thing make you feel?" (Excited!) "What else makes you feel
that way?" (Java!) We ended up with a board covered with essentially
random words. Then he put us through a sorting process where we ended
up with a ranking of the names. We ended up with a dozen name
candidates and sent them off to the lawyers: they worked down the list
until they hit one that cleared their search. "Java" was the fourth
name on the list. The first name on the list was "Silk", which I hated
but everyone else liked. My favorite was "Lyric", the third one on the
list, but it didn't pass the lawyers test. I don't remember what the
other candidate names where.

So, who named Java? Marketing organized the meeting, the
consultant ran it, and a whole pile of us did a lot of yelling out of
random words. I'm honestly not real sure who said "Java" first, but I'm
pretty sure it was Mark Opperman.

There certainly wasn't any brilliant marketing mind who went through a coherent thought process.

URL: http://blogs.sun.com/jonathan/entry/better_is_always_different
GridGain: Presenting at JavaZone 2007

Posted: August 31, 2007, 8:56am CEST by Nikita Ivanov

I will be presenting at JavaZone 2007 in Oslo, Norway September 13-14. JavaZone is one the largest European Java conferences and this is a great opportunity for us to talk about GridGain project and most importantly about the technology and ideas behind it and our view on grid computing in general. I will be presenting on "Java Grid Computing with AOP – Fun, Simple and Productive". In this presentation I will show a live coding example where I will create a simple grid application in just 10-15 minutes. Should be fun!
JavaZone is a must go if you can travel (and if you are in Europe – you are just couple of hours flying away at the most).
It's always something simple...

Posted: August 31, 2007, 8:49am CEST by Lazy Guru

So I finally stumbled across the problem that has been plaguing me with my spring/hibernate application. It turns out it was the database's fault. Well, OK, it's not the database's fault. But still ....
The problem was due to the fact that one of the objects was declared having an ID of type String (java.lang.String) and the database column was a CHAR(20) while the data was only of length 16. (Have you figured out what the problem was yet?). Apparently, Hibernate recognizes a difference between "ABCD" and "ABCD ". Once I created a view that wrapped the column in a TRIM(), everything started working beautifully.
So that's the short version of what happened. If your curious about the long version, read on.
I started by alternating between bag and set while moving inverse="true" to either hbm.xml file (thanks for the pointer Eric). No matter what I did, I still couldn't retrieve the List (or Set) of objects; and, to make matters worse, I wasn't getting any error messages. Then I ran across a blog entry that talked about the difference between load and get. I noticed I was using load, so I changed it to get. I also read some blogs about not using the Spring templates and wrappers, so I made my DAO extend HibernateBaseDao and changed my calls to use the HibernateTemplate. Then, wham! I started getting error messages about the ID being changed (or something like that, sorry I don't remember the exact message). Well, if you read my previous entry you'd know that an error message can be a good thing. After a little bit of googling with no luck on a solution, I ran across a forum post describing the issue and mentioning the trailing spaces. Then it occurred to me to try wrapping the column in a TRIM(); and, well, you know the rest. Everything works great now. I can retrieve a List of either object from either side.
All in all, I'd say it was a good learning experience and hopefully someone else who's having similar problems will stumble across my blog and be inspired with an answer to their problems. (If so, please let me know )
Love and Hate Java

Posted: August 31, 2007, 7:59am CEST by Paul Gregoire
Sometimes I really hate coding.. These periods are short lived but arise from messages such as this:
```
java.lang.ClassCastException: 
org.springframework.context.access.ContextBeanFactoryReference cannot be cast to 
org.springframework.context.access.ContextBeanFactoryReference
```
I assume this is a classloader issue but I'm not yet sure how to solve it. The same jars (versions) are available on the classpath and the webapps are running under a single instance of Tomcat. Any ideas??
Update
After reading the Classloader chapter of "Professional Apache Tomcat 5" I found a way around this "problem" by putting the spring jars under the "shared" classloader which means to put them in tomcat/lib for Tomcat 6. The exception is caused when two different classloaders within the same VM load the same class. It is raised when you try to manipulate them in someway in the classloader that loaded the opposite class. To make a long story short I decided not to write my own classloader but to load all the main classes into one war and make connections from the other wars via HTTP.
Single-responsibility principle and class design (this time in C++)

Posted: August 31, 2007, 7:04am CEST by Tiago Silveira
As some of you know, I haven't written a single line of Java code since I joined Google in April. I've been working mostly with C++. As usual, you won't find any Google-specific information in this post.

I have always been a fan of Test-driven development. Good unit tests make extensive use of Mock objects, so I am a fan of Dependency Injection as well. In its bare form, where we don't have a magical container that injects dependencies for us, we're talking about DI's origins, Inversion of Control: taking away the control flow of instantiation from inside the classes. Inversion of Control is a technique that helps you enforce the Single Responsibility Principle: the idea that each class should have one and only one purpose, one (small) thing that it's responsible for — and delegate all the rest. In the specific case of instantiation, it also delegates the construction of objects.

For example, if a class uses a special map that you can, say, load and save to a file, but the main responsibility of the class is to process something doing lookups on the map, you can refactor the map code to a separate class, say, SpecialMap, and leave the original class with the processing code, delegating the lookup to SpecialMap. You would then pass the SpecialMap in the constructor, fully initialized and ready for use. In Java, this is peanuts. In C++, it might be hard work, because all classes have one additional responsibility, namely memory management.
```
// this doesn't work:
MyObject start(const string& param) {
  MyDelegate delegate(param);
  MyObject obj(delegate);
  obj.start();
  // return-by-value, this will copy obj
  // into another instance!
  return obj;
  // delegate gets destructed here!
}
```
In C++, local variables have local scope, and the default behaviour is pass-by-value. This means that object instances are copied around. In the snippet above, two things might happen:
1. MyObject's constructor receives a full, pass-by-value instance of MyDelegate, so delegate will be copied into obj;
2. MyObject's constructor receives a reference, which is transparent to the call. The caller never knows if he's passing a reference or the instance.
If the former is true, then a new instance of MyObject will be stored in the variable that calls the function start(), thus copying the delegate object a third time! This is hardly ever what you want.

Side note: Java only has pass-by-value. But Java variables are either primitives or references: there are no object variables nor pointer variables. And that's a pretty good reason to provide garbage collection. In 1994, Java was slow not only in the evolutionary sense.

What people do in C++ is allocate the object from the heap using new and write the constructor to receive a pointer to an object:
```
class MyObject {
  public:
  MyObject(MyDelegate* delegate);
  ~MyObject();

  private:
  MyDelegate* m_delegate;
};

// Now this works:
MyObject* works(const string& param) {
  MyDelegate* delegate = new MyDelegate(param);
  MyObject* obj = new MyObject(delegate);
  obj->start();
  return obj;
}
```
But who's responsible for the deallocation of these objects? To avoid memory leaks, it must be clear to the clients. Anybody instantiating a MyObject should know right away if it's going to delete the delegate when it's gone. Suddenly everybody is busy with lifecycles, because either:
- MyObject doesn't delete m_delegate, and thus the instance created by the client must live at least as long as MyObject; or
- MyObject deletes m_delegate in its destructor and the MyDelegate instance created by the client can only be used as long as MyObject is alive
So much for separation of concerns, right? I never thought that adding inversion of control to code would encourage the use of Evil Singletons.

A little research brought me to this post by Michael Feathers where he explains why building a decent DI framework for C++ is so difficult. Add to that that your own code using DI is nothing trivial and I wonder if we're ever going to see the end of the tunnel here.

In practice (and remember, I have only a few months practice, a little more if you count my graduation years), it's easy do choose what's going to happen: either the two lifecycles are completely intertwined, or the two objects have independent lives and it's pretty easy to know who dies first. Two examples:

Example 1: Your code parses some text and does something else with it, the parsing should be delegated to a separate class. But there's no reason for anyone else to reuse the parser, so you explicitly state (by leaving a comment) that your class deletes the parser when it's destroyed.

Example 2: Your code uses a heavyweight object like a GUI toolkit, connection pool, etc. In general, these big, heavy objects are designed to be used by many different objects and have easily recognizable traits (for example, being thread-safe). So you should explicitly state that you don't delete the object when your class is destroyed.

My conclusion is that it's a tough problem, but usually easy to feel what is the right approach. And your answer will also lead you to consider your own class: is it something that clients will want to use in many different objects, or is it more likely that people who delegate to your class will declare local variables of it and/or cascade delete it? And if you really have to do all this thinking, is a DI framework valuable at all?

P.S.: If the Java world had been forced to think about this issue for every class ever to join the API, maybe the StringBuilder would have come out much, much sooner.
Red Hat Developer Studio Mini Review

Posted: August 31, 2007, 3:18am CEST by David Heffelfinger

I am currently working on a project involving JSF, Facelets and JPA. I had recently downloaded Eclipse Europa, specifically the JDT and WTP. Unfortunately WTP does not include Facelets support by default, but I had read somewhere that RHDS does, therefore I decided to download it and take it for a spin.

In case you have been living in a cave for the last few years, let me give a very brief introduction to Facelets. By default, JSF uses JSP as its view technology, but allows this default view technology to be replaced by an alternative view technology. Facelets is a very popular alternative view technology for JSF. Facelets are usually written using XHTML. XML name spaces are used for JSF specific components.

The standard XML editor that comes with the Eclipse Web Tools project does not offer autocompletion of JSF components when editing XHTML, but the XHTML editor in RHDS does. In my experience, the editor completion worked as expected, the only problem I found was that RHDS would occasionally freeze. Unfortunately it froze frequently enough that I found myself switching to good old Eclipse Europa when working with artifacts other than Facelets, then switching back to RHDS to get Facelets autocompletion.

By the way, even though JBoss is now a Red Hat product, RHDS does not tie you to JBoss, I am, as a matter of fact, deploying the project I'm developing with RHDS to GlassFish without any difficulty.
GlassFish Book Publication Date Details

Posted: August 31, 2007, 2:59am CEST by David Heffelfinger

I received a tentative date in which my new book, Java EE 5 Development With GlassFish Application Server, will be published. Expect to see it in select online and brick and mortar bookstores on or before September 24^th.

It will be available on Amazon, BookPool, Borders, and others. Additionally it is currently available for pre-order directly from Packt Publishing.

The book covers all major Java EE APIs including JSF 1.2, EJB 3, JPA, JAX-WS and more. Additionally, frameworks that build on top of Java EE are covered, including Facelets, Seam and Ajax4jsf
Retiring JVending

Posted: August 31, 2007, 1:17am CEST by Shane Isbell

After three and half years, I am finally retiring JVending on sourceforge. Over the years, I have uploaded a number of interesting mobile projects under JVending: a JSR-124 implementation (with P2P content sharing), a J2ME MMS client (JDJ Article), J2ME DRM wrapper, a PPG Client and a registry framework for CDC devices.

I have a newer version of my 2001 J2ME GPS client ( JDJ Article) still sitting on my computer that I never uploaded (this newer version was originally for a client that backed out). I also have a fairly complete implementation of the MMI spec (DRM). A good portion of my life went into these projects, but I haven't done a release in over a year.

Since there is no JVending community, with my schedule I can't justify spending more time on development. Looking back, I can see why building a JVending community was so hard: not many people need to setup their own mobile provisioning server; most don't know what a PPG is (even if they had access); and they certainly aren't going to be interested in adding DRM.

My expectation back in 2004 was that a lot of enterprises would start looking for ways to directly enter the mobile content area and this would be JVending's niche. A lot of enterprises did start entering the mobile content area (I got some good consulting gigs out of it), but eventually these companies found that dealing with carriers was such a pain, they started going through aggregators that had pre-existing relationships with the carriers. It's a carrier's market and carriers aren't going to deploy anything without support of a backing company.

JVending is still the only open-source version of JSR-124 that I know of. It hasn't passed a TCK, but if you are interested in poking around the code to see how it works, download the source; feel free to contact me with any questions.

Comfortable XPath accessor

Posted: August 31, 2007, 12:50am CEST by Daniel Schneller

Three weeks ago I blogged about a "Groovy way" to create XML documents in Java. This article now is about a convenient way to access XML without requiring more than a single class (downloadable here) on top of the JRE's own XML library functions.

In fact I wrote this class before I even looked for an easy way to create XML myself, because at the time I just had to parse some XML and extract the values in an easy to use fashion.

I believe it is easiest to show an example of how to use the class. Consider the following very simple Java class:

import java.math.BigDecimal;

/**
 * Simple value object for a contact.
 */
public class Contact {
    public String firstname;
    public String lastname;
    public boolean withAccount;
    public Integer numberOfCalls;
    public BigDecimal amountDue;
}

Usually the fields would not be public of course, but for the sake of the example, just imagine the getters and setters being there ;-)

Now consider getting an XML string back from an external system that you cannot change:

<representative>
   <address>
         <street>Somewhere</street>
         <city>Over The Rainbow</city>
         <details>null</details>
   </address>
   <personal>
       <name>Someone</name>
       <firstname>Special</firstname>
       <age>55</age>
       <acct>true</acct>
   </personal>
   <supportHistory>
       <phone>
          <total>14</total>
          <x11>5</x11>
          <x12>9</x12>
       </phone>
       <incident>
          <id>1</id>
          <cost>1.50</cost> 
       </incident>
       <incident>
          <id>2</id>
          <cost>2.50</cost>
       </incident>
       <incident>
          <id>3</id>
          <cost>3.50</cost>
       </incident>
       <incident>
          <id>4</id>
          <cost>4.50</cost>
       </incident>
   </supportHistory>
   <current> 
       <due>44.12</due>
       <total>100.88</total>
   </current> 
</representative>

What's the easiest way to get this into the “Contact” class above, without using persistence frameworks, mapping tools and the like? What about this:

XPathAccessor acc = new XPathAccessor(someXML);
Contact contact = new Contact();
     
contact.firstname = acc.xp("representative", "personal", "firstname");
contact.lastname = acc.xp("representative", "personal", "name");
contact.withAccount = acc.xpBool("representative", "personal", "acct");
contact.numberOfCalls = acc.xpInt("representative", "supportHistory", "phone", "total");
contact.amountDue = acc.xpBD("representative", "current", "due");

I find this rather straightforward. Of course the Strings should be declared as constants somewhere to prevent typos.

The example is really simple, because we just extract some plain values from the XML. However, you have the full power of XPath at your disposal. This means you could do something like this:

BigDecimal getTotalIncidentCost(String someXML) throws SAXException,      
     IOException, ParserConfigurationException, XPathExpressionException {
    XPathAccessor acc = new XPathAccessor(someXML);
    BigDecimal tResult;
    Node historyNode = acc.getNode("representative", "supportHistory");
    tResult = acc.xpBD(historyNode, "sum(incident/cost)");
    return tResult;
}

The XPathAccessor instance could (and should) be reused, of course, depending on how often you need to access the document. As it caches XPath expressions that have already been used, it saves some cycles to re-use it for all accesses to a particular document.

Getting the “historyNode” first is of course not really necessary in this simple case, however sometimes it can come in handy to keep the expressions readable when you need to access deeper parts of the XML.

As with the XElement class, feel free to use this one, too. I would be happy to get feedback and/or improvements.

Get Lazy

Posted: August 30, 2007, 9:04pm CEST by Chris Mathias
This is basically a dump from my wiki entry at [code.google.com]

OK, this seems totally obvious now that it's all worked out. However, working it out was...well...less than obvious. Once again Paul Hixon turns the Crank. Here's the 'gold standard' configuration for making your Entity Manager/Hibernate Session/Domain Objects live long enough to see their children.

The obvious part is employing the OpenEntityManagerInView interceptor (or filter - but I never did get that one working right).
```
    <bean id="openEntityInView"
```
```
        class="org.springframework.orm.jpa.support.OpenEntityManagerInViewInterceptor">
```
```
        <property name="entityManagerFactory">
```
```
            <ref local="cep-webEntityManagerFactory" />
```
```
        </property>
```
```
    </bean>
```
The not-so-obvious part is how to get this to actually apply. I had tried several configurations of bean name proxies and whatnot, before Paul finally hit the spot with this one. Again - duh - but somehow just from reading the docs it didn't all quite click in. Note the reference to to the intereceptor in the servlet handler.
```
    <bean id="handlerMapping"
```
```
        class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping">
```
```
        <property name="interceptors">
```
```
            <list>
```
```
                <ref bean="openEntityInView" />
```
```
            </list>
```
```
        </property>
```
```
    </bean>
```
S'alright?! Sok! Thank you Paul. You saved my hairy...well...n/m. You really helped me out again.
Spring Controller Upload Progress Bar

Posted: August 30, 2007, 8:48pm CEST by Massimiliano Dessì

Il SimpleFormController per l‘upload di MagicBox si è abbellito con la barra di stato dell‘ upload

Ricetta :
1 SimpleFormController
1 AbstractController
1 JSP
2 Velocity Template
1 Commons Upload Listener
1 prototype script
css a piacimento

La prossima settimana articolo completo + recensione Spring in Action Second edition

Stay Tuned
OpenJPA 1.0.0 is now available

Posted: August 30, 2007, 8:27pm CEST by Patrick Linskey

Earlier this week, the OpenJPA community released OpenJPA version 1.0. The release is available for download at http://openjpa.apache.org/downloads.html. Read the release notes for more details.

I'd like to thank Marc Prud'hommeaux in particular for all his hard work getting the release built and automating a significant amount of the process.
Offbeat: San-Francisco Minute

Posted: August 30, 2007, 7:16pm CEST by Nikita Ivanov

I was riding back home today on the BART (local train transportation system here in Bay Area). I got down on the escalator and got in line for the train. Right in front of me there was a guy with a backpack that had .NET emblem from some conference. I looked down the line and saw another guy just two or three people away with... Java logo backpack. At this point I thought to myself that I have my own t-shirt with "Bamboo – Well Built" in my bag from the gym. About that time (not making this up) train arrived on opposite platform and one guy caught my eye getting off the train wearing white t-shirt with all too familiar green leaf and some text beneath of… Spring Framework.
All that happened in a span less than a minute. Just a short San Francisco minute...
Verizon UAProfs

Posted: August 30, 2007, 6:41pm CEST by Fred Grott

Verizon still will not allow down loading of j2me applications. However UAprofs are not accessible from non Verizon users. for example this one:

http://uaprof.vtext.com/lg/vx4500/vx4500.xml
Moving to JBoss4.2.1+JBossWS 2.0.1 from JBoss4.0.4

Posted: August 30, 2007, 5:08pm CEST by Genady Beryozkin
This blog entry is a summary of changes I had to implement in order to migrate some EJB3+web services code to the new platform. From the other side of the webservices we have a C# .NET2.0 client. This is not an official reference, and probably few things that I did are the wrong approach. I was trying to minimize changes to the .NET code and try to stay as close to the standards.

NOTE0: I don't have much time to write this summary, so typos and omissions are possible...

NOTE1: The decision to move to JBossWS2.0.1 was almost arbitrary. I switched to the new version because I hoped that some of the stuff that didn't work right away will work in the new version.

NOTE2: When referring to JBoss4.0.4 I collectively refer to all the libraries that ship with it.
The @EJB annotation
JBoss 4.0.4 was released with EJB3 support still in beta. Therefore the @EJB annotation was still in the javax.annotation package. In later releases, including JBoss 4.0.5, it has moved to its final destination in the javax.ejb package. The symptoms of missing this step (and deploying code linked with 4.0.4 on 4.2.x server) : Dependency injection simply doesn't work, and all the "injected" fields are nulls.
Missing constructors/setters
JBoss 4.0.4 has allowed classes that participate in webservices (as parameters or return values) to omit the default constructor if the class was never to be constructed by the remote side. In the new version, all such classes must have a default constructors. Additionally, JBoss 4.0.4 has recognized such classes as beans even if a setter was missing (again, if the class was constructed on the Java side). Now I found that all setters must be present, or each getter must be annotated with the @XmlElement annotation.
The WebContext and the web context root
In JBoss4.0.4, the context root of all the webservices was the file name of their common jar file. For example, if our beans were jarred in a beans.jar file, then the context root would be "/beans" and the webservices can be accessed at [localhost:8080] . This behavior has changed in JBoss4.2.1 (that ships with JBossWS1.2.1) and now each webservices class defines its own context root, which by default is the class name. So if you have 5 classes you end up with 5 different context roots. JBoss doesn't like it and will issue an error at deployment time. The solution is to manually add the JBoss-specific @WebContext annotation to each class, like @WebContext(contextRoot="/beans"). JBossws 2.0.1 uses some kind of compatibility mode, in which there is no need to use the special @WebContext annotation, but the default context root has changed to include the name of the EAR file. So if the beans.jar file is put into a demo.ear file, the context root of the webservices will be [127.0.0.1:8080]. In order to override the new default context, it is possible to use a new annotation @org.jboss.wsf.spi.annotation.WebContext(contextRoot="/beans") on just one of the services.
Capitalization
Another incompatibility is the way in which the parameter classes are named in the WSDL and therefore in the .NET client. For example, if in 4.0.4 I had a webservice that looks like
```
@Stateless
@WebService
public class TestClass2 {

	@WebMethod
	public MyClass getMyClass() {
		return new MySubClass();
	}
}
```
The "MyClass" identified would appear in the WSDL as "MyClass". In newer versions, it is decapitalized to begin with a lowercase letter: "myClass". It breaks the existing .NET code, so I had to manually add the @XmlType(name="MyClass") annotation to the MyClass definition (and to the few dozens of classes that I used).
Passing webservice method parameters
One of the most significant changed in the new webserives implementation is the way it passes parameters and return value of primitive wrapper types (Integer, Long). Previously, such parameters would be defined in the WSDL as "nillable" and the corresponding .NET definition would represent them as .NET nullable types (e.g, "int?"). In the new webservices library, such parameters are given the maxOccurs="0" attribute in the WSDL and therefore appear in .NET as a pair of "int param" and "bool paramSpecified" fields. I could not find a way to cause the parameters to behave like in 4.0.4, so I had to modify our .NET code. Return values have the same problem - if an Integer is returned from Java, it is split into two fields "returnSpecified" which is true if null is returned and "@return" (yes, the "@" symbol escapes the "return" keyword) that contains the returned value. Last issue (the easiest to spot and fix) - the default argument names (if no @WebParam attribute is used) have change to follow the spec (now they are arg0, arg1, etc).
More JAXB issues
When bean classes that are used by the webservices are translated into XML, few incompatibilities arise:
- The class should be annotated with @XmlType(name="TypeName") to avoid decapitalization.
- Wrapper type properties (Integer, Long, etc) should be annotated with @XmlElement(nillable=true, required=true) on the getter to translate them as int? in .NET
- The opposite should be done for properties that are arrays of primitives (int[], float[]). These properties should be annotated with @XmlElement(nillable=false) in order to be translated as int[] and not as Nullable<int>[] (that is array of nullable ints, not an array pointer that can be null).
Inheritance
Sometimes a webservice returns a class that has subclasses, as in the following example:
```
@Stateless
@WebService
public class TestClass2 {

	@WebMethod
	@SOAPBinding(parameterStyle=ParameterStyle.WRAPPED, use=Use.ENCODED)
	public MyClass getMyClass() {
		return new MySubClass();
	}
}
```
```
      
      @XmlType(name="MyClass")
public class MyClass {

// field+method definitions here
}
```
```
      
      @XmlType(name="MySubClass")
public class MySubClass extends MyClass {

}
```
In JBoss 4.0.4 there was no problem. The .NET client would correctly receive the MySubClass as a return value. JBoss4.2.1+JBossws2.0.1 send MyClass to the .NET client. The @XmlSeeAlso annotation should hit the web services implementation that a subclass could be involved in the method call. However, simply using the annotation was not enough (.NET would complain about the SOAP message format). In addition to the @XmlSeeAlso(MySubClass.class) annotation on the MyClass class, I also had to add a namespace attribute to the @XmlType annotation.
Duplicate methods
One of the most bizzare bugs that I've encountered was a case when I had two different @WebService-s in the same package, and both had the same method signature, except the return type:

package demo;

@Stateless
@WebService
public class TestClass1 {

@WebMethod
public long getValue() {
return 5;
}

}

package demo;

@Stateless
@WebService
public class TestClass2 {

@WebMethod
public int getValue() {
return 5;
}

JBoss confuses between the two and both methods will have the same return type in WSDL (e.g, both will return int). I couldn't find a solution, so I just had to rename one of them.
Upgrading to a newer Hibernate
Recently I discovered what I think is an instance of the EJB-263 bug. Hibernate JPA queries that should return a single result (I used "JOIN FETCH" to fetch some lazy collections) were returning multiple results - in fact if my single element has 100 elemenets in the lazy collection, I would get 100 elements from the query - all of them are the same object instance. To resolve it I had to upgrade to a newer hibernate (I used Hibernate 3.2.5, Hibernate Annotations 3.3.0 and Hibernate EntityManager 3.3.1). Note - during upgrade, you should copy the helper libraries (lib folder) too.
FEST 0.5: support for drag n' drop and legacy apps testing

Posted: August 30, 2007, 3:46pm CEST by Alex Ruiz
We just released FEST 0.5!

New features:
1. Added drag 'n drop support for JList, JTable and JTree. Many thanks to Fabien Barbero for his contribution.
2. Added support for custom matchers for component lookup. This feature is useful when testing GUI components that don't have an associated name (e.g. testing legacy applications.) Custom matchers are implementations of GenericTypeMatcher. The following example shows how to lookup for a JButton that has the text 'OK':
```
GenericTypeMatcher<JButton> textMatcher = new GenericTypeMatcher<JButton>() {
  protected boolean isMatching(JButton button) {
    return "OK".equals(button.getText());
  }
};
dialog.button(textMatcher).click(); 
```
3. Added utility class Platform, which contains platform-specific utility methods.
4. ContainerFixture now recognizes JFileChooserFixture and JListFixture. Many thanks to Fabien Barbero.
5. Fixed Issue 15. Now it is possible to follow frames with FEST.
6. Swing module and the extensions for TestNG and JUnit are included in one zip file.
You can download FEST here (file fest-swing-0.5.zip.) FEST requires Java SE 5.0 or later.

Here are some useful links:
- Changelog
- []
- Javadocs
- Dependencies
- Getting Started
- Issues
- Users' Group
Feedback is always appreciated
Play. Estimate. Plan - Ferramenta Ágil para simular Planning Poker

Posted: August 30, 2007, 2:02pm CEST by Leonardo Fernandes Mendonça de

Play. Estimate. Plan...assim diz o título desta ferramenta da Mountain Goat Software (Empresa conhecida pelo pessoal de Scrum). É uma aplicação na web que tem por finalidade simular um Planning Poker para equipes que estão fisicamente distribuídas. Isso por que uma das premissas dos métodos ágeis é a forte comunicação e para equipes que estão cidades/estados/países diferentes isso vai ficando cada vez mais escasso.

Como funsiona a ferramenta:

Uma pessoa é o moderador. Após ela efetuar login ela convida outros participantes para participar do game. Então a pessoa entra com uma estória para ser estimada. O time claro, precisará está numa mesma conferência, onde eles discutirão sobre o a estória. Depois cada participante escolhe um cartão sua estimativa para implementar aquela estória e aí então o moderador escolhe a estimativa para aquela estória.

No canto direito possui um botão de timer de dois minutos que é um tempo razoável para escolher as estimativas. Após isso a decisão pode ser exportada para formatos conhecidos como CSV e PDF (Essa funcionalidade eu não usei)

Acho que esta ferramenta tem muita utilidade em “equipes ágeis” que utilizam o planning poker e não estão localizados numa mesma sala.

Link da ferramenta aqui.

_uacct = “UA-2402321–1”;

urchinTracker();
NetBeans javacvs Library

Posted: August 30, 2007, 10:51am CEST by Nanik Tolaram

Currently I'm in the middle of automating the creation of new projects in CVS and CruiseControl. I've found the way to automate the projects in CVS repository using the NetBeans javacvs library. One thing though if we are testing the CVS server installed in our local machine we have to use the LocalConnection class instead of the PServerConnection class.

As for CruiseControl I think if there is no API or web service call then I can just add the configuration into the config.xml and automatically CruiseControl will pick it up.
GridGain To Grid Computing Is Like RoR To Web Development

Posted: August 30, 2007, 10:08am CEST by Nikita Ivanov

That's what WTF record says on Technorati for “GridGain”. I think it describes it some what accurately, although similarities are rather superficial. GridGain is all about doing to grid computing what Spring and Jboss accomplished for J2EE just few short years ago. Hm... there goes another “is like” comparison.
While we are at it let me rephrase it yet another way - “With GridGain we've taken Saint Exupery's principle quite literally”.
Have fun and enjoy grid computing!
Download GridGain at [www.gridgain.com].
Eclipse Myths

Posted: August 30, 2007, 9:56am CEST by Utta

To be able to collaborate well with Turmalix, hosted on the free, open collaboration platform JavaForge, the use of an Integrated Development Environment (IDE), on the desktop site, is more than nice to have. To make it fun working with JavaForge/Codebeamer, you have a choice of free IDE's to be downloaded from the web. The most famous ones are Eclipse and Netbeans.
There are philosophies on which IDE to prefer. I am grateful for all of them. Thanks to our new free open source culture, we seem to be living in paradise. Now we all can afford great software and be part of this adventurous open source circus. It is more like living as an artist than being an engineer. The collaboration in the web is the source for our inspirations and our creativity.

Eclipse is more than a myth: according to wikipedia the term is most often used to describe either a solar eclipse, when the Moon's shadow crosses the Earth's surface, or a lunar eclipse.
Wikipedia also has a perfect introduction to the Eclipse IDE. For developers to collaborate with Turmalix on our collaboration platform, we want to download the free open source software piece at the community site www.eclipse.org.
To explain how to install and set up eclipse would kill this weblog. Voila, it is done for you already: see "The Official Eclipse FAQs".
To be able to connect the IDE to the Turmalix subversion archive on JavaForge, we use the Eclipse plugin called Subclipse. This plugin gives us a simple and well integrated connection between our Windows or Linux desktop / laptop and our collaboration area. For details see 10 Steps - Accessing the Turmalix subversion archive with a client.
3 Hot Techniques from an expert Java developer

Posted: August 30, 2007, 6:20am CEST by Jesse Sightler
Here are some great tips from looking at some high quality source code: Reading From Streams I know the length of the stream, so I'll just do this:
```
InputStream is = openStream();
byte[] data = new byte[dataLength];
is.read(data);
```
InputStream.read would never return less than the full length of the data, right? Copying a stream of unknown length If you don't know the length of the stream you are reading, you will need an efficient and dynamic data structure to copy it into. Here's a perfect example:
```
Vector byteVec = new Vector();
byte bRead;
while ( (bRead = inputStream.read()) != -1) {
    byteVec.addElement(new Byte(bRead));
}
byte[] data = new byte[byteVec.size()];
for (int i = 0; i < byteVec.size(); i++) {
    data[i] = ((Byte)byteVec.elementAt(i)).byteValue();
}
```
Unfortunately, the most efficient way to do this in Java is a synchronized, dynamic list structure, byte wrappers, and lots of typecasting. Exception Handling
If you ever have trouble with null pointer exceptions, just sprinkle these liberally throughout your code (preferrably lots of times in the same method, where the same variable is likely to be null):
try {
b.doSomething();
} catch (NullPointerException e) {
// ugh, it broke again, just ignore the thing
}
Callers never really want to see that the callee failed.
Summary
Yes, these are actual examples from real code. I will not mention the developer by name. You will have to work quite hard to reach these levels... of... well... of something!
Follow-up To The Technique For Loading External Properties

Posted: August 30, 2007, 5:09am CEST by Matt Albrecht
A quick follow-up on yesterday's post. After running through my unit tests, it appears that I forgot a basic element of Java usage: order of execution for constructors.
By setting a property to a new object directly in the field definition:
```
public class MyProperties extends PropertyGroup {
    public final StringProperty myString = new StringProperty("default string");
    public StringProperty myString2;
    public final IntProperty myInt = new IntProperty(10);
    public final FooBazProperty myFooBaz = new FooBazProperty("file.txt");
    
    public MyProperties(Properties p) {
        super(p);
    }
}
```
that code for constructing the object is executed after the constructor completes. Therefore, if you allow for the class to construct new instances dynamically if the field is null, or if methods need to be called on the fields, it needs to run after all the fields have been initialized. This means that the setup code cannot be in the constructor.
Which makes yet another argument for supplying factory methods. Instead of forcing the user of the class to create a new object then run a setup method, just have the class provide a factory method.
Crank Validation Design Document

Posted: August 30, 2007, 3:43am CEST by Rick Hightower

This document discusses the current design of the Crank Validation framework. Specifically it covers the base framework not the specific JSF and Spring MVC bindings nor for that matter does it cover the Ajax/JavaScript support.

The document starts off talking about the Spring MVC and JSF neutral parts of the framework. Later it does discuss the Spring MVC and JSF bindings just enough to understand how the base framework is used.

This document does not cover the Ajax support for calling validation rules, the low level JSF integration, the low level Spring MVC integration, or the JavaScript based rule generation. Perhaps, one day those documents will exist.

Before reading the Crank Validation design doc, it may make sense to see some example code at: [code.

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