Knowledge Is Everything

Quick way to join array of String in Java without third party libraries

2012-01-21T16:31:00.000+02:00

As you probably know Java SE doesn't include such useful method as String join. Even old good JavaScript has this nice method:

JavaScript join() Method
Definition and Usage
The join() method joins all elements of an array into a string, and returns the string.The elements will be separated by a specified separator. The default separator is comma (,).

How to implement the similar stuff in Java SE? The easiest what came to my head is:


 /**
  * Join String arguments into one String separated by comma (",")
  * @param args input Strings
  * @return joined String
  */
 public static String join(String... args) {
  if(args.length <1) throw new IllegalArgumentException();
  
  String joined = Arrays.toString(args);
  String result = joined.substring(1, joined.length()-1);
  return result;
 }

Usage is pretty trivial:


import static com.blogspot.HalypHUtils.join;

...

String joinedString = join("Banana", "Orange", "Apple", "Mango");

And as you've already noticed this join uses comma (",") separator only.

What is the best book for SCJP/OCPJP exam preparation?

2012-01-09T13:25:00.001+02:00

There are two major books for the exam preparation:

SCJP Sun Certified Programmer for Java 6 Exam 310-065, by Katherine Sierra, Bert Bates

A Programmer's Guide to Java SCJP Certification: A Comprehensive Primer (3rd Edition), by Khalid Mughal, Rolf Rasmussen

I've read both books and must admit that "SCJP Sun Certified Programmer for Java 6 Exam 310-065, by Katherine Sierra" is the best. You can also have a look into

OCP Java SE 6 Programmer Practice Exams (Exam 310-065) (Certification Press), by Bert Bates, Katherine Sierra
I can say it's like a companion book there are a plenty of nice mock exam questions.

I can say that you shouldn't use "A Programmer's Guide to Java SCJP Certification: A Comprehensive Primer (3rd Edition), by Khalid Mughal, Rolf Rasmussen" because:

there too many unnecessary info which is totally useless on exam
book written style isn't perfect, it's really hard to follow the main idea
explanation of some ideas is very complex and bloated, it can be simplified
book typographic style is really ugly in comparison with "SCJP Sun Certified Programmer for Java 6 Exam 310-065, by Katherine Sierra"

Your can simplify your exam preparation if you stick to one book. Keep in mind your goal is optimize the exam preparation and avoid the redundant reading.

How to decide which technology hype is worth personal investments?

2011-12-25T21:16:00.000+02:00

I think it's very important question. Because studding some new technology requires some time (and maybe money).

So, I've created for myself brief checklist which helps me to make this non-easy decision.

How long it will take for me to master the major approaches of selected technology?
Can I reuse the gained knowledge during my daily development work?
How long it will take to train/coach my team mates to use this technology?
How big is the market for the selected technology?
How big is the local community for the selected technology?
How easily can we hire new developers with appropriate knowledge in selected technology?
Will it be profitable to have the knowledge in that technology?

I know that some items are very boring and mercantile, but it's life, real life. And we should align our priorities appropriately.

How to run ANT script from .BAT/.CMD?

2011-11-03T15:04:00.003+02:00

Imagine you need to call ANT script from BAT/CMD file.
Ant script:

And here is BAT file:

@echo off
echo BAT - Before Ant run
ant -f build.xml
echo BAT - After Ant run

Unfortunately, when you run this BAT you get the next output:

BAT - Before Ant run
Buildfile: D:\Projects\blog\build.xml

bat-test:
     [echo] Message from ANT

BUILD SUCCESSFUL
Total time: 0 seconds

So, where is the "BAT - After Ant run" echo message?

The problem is that Ant on Windows executed via ant.bat file and based on this we're calling one BAT file from another. We have to use CALL command to solve this issues, here is official note from CALL help:

Calls one batch program from another.
CALL [drive:][path]filename [batch-parameters]
batch-parameters Specifies any command-line information required by the batch program.

And, here is the update BAT file:

@echo off
echo BAT - Before Ant run
call ant -f build.xml
echo BAT - After Ant run

Java Reflection: Invoke Constructor Issue

2011-10-21T12:37:00.000+02:00

Let's imagine we have the next classes:

package test.clazz;

public class First {
 private FirstArg arg;

 public FirstArg getArg() {
  return arg;
 }

 public First (FirstArg arg) {
  this.arg = arg;
  System.out.println("First() - constructor");
 }
}

public class FirstArg {
 public FirstArg() {
  System.out.println("FirstArg.FirstArg()");
 }
}

public class SecondArg  extends FirstArg{
 public SecondArg() {
  System.out.println("SecondArg.SecondArg()");
 }
}

And we can easily instantiate First class with FirstArg or SecondArg:

First f1Old = new First(new FirstArg());
First f2Old = new First(new SecondArg());
System.out.println(f1Old.getArg().getClass());
System.out.println(f2Old.getArg().getClass());

We'll get the next output:

FirstArg.FirstArg()
First() - constructor
FirstArg.FirstArg()
SecondArg.SecondArg()
First() - constructor
class test.clazz.FirstArg
class test.clazz.SecondArg

Now, we have to instantiate First class with FirstArg or SecondArg, but via Java reflection:

public final class ConstructionUtil {
 public static Object instantiateClassOld(String className, Object iView) {
  try {
   Class iViewClass = iView.getClass();
   Class clazz = Class.forName(className);

   Constructor ctor = clazz.getDeclaredConstructor(iViewClass);
   ctor.setAccessible(true);
   return ctor.newInstance(iView);
  } catch (Exception e) {
   e.printStackTrace();
   return null;
  }
 }
}

Check reflection based class instantiation:

Object cls = instantiateClassOld("test.clazz.First", new FirstArg());
First f1 = (First) cls;
Object cls2 = instantiateClassOld("test.clazz.First", new SecondArg());
First f2 = (First) cls2;
System.out.println(f1.getArg().getClass());
System.out.println(f2.getArg().getClass());

And we'll get Exception:

FirstArg.FirstArg()
First() - constructor
FirstArg.FirstArg()
SecondArg.SecondArg()
java.lang.NoSuchMethodException: test.clazz.First.(test.clazz.SecondArg)
 at java.lang.Class.getConstructor0(Unknown Source)
 at java.lang.Class.getDeclaredConstructor(Unknown Source)
 at test.ConstructionUtil.instantiateClassOld(ConstructionUtil.java:63)
 at test.ConstructionUtil.main(ConstructionUtil.java:22)

Reflection mechanism can't find First(SecondArg arg) constructor.
We have to patch instantiateClassOld method like this:

public final class ConstructionUtil {
 public static Object instantiateClassNew(String className, Object iView) {
  try {
   Class iViewClass = iView.getClass();
   Class clazz = Class.forName(className);
   try {
    Constructor ctor = clazz.getDeclaredConstructor(iViewClass);
    ctor.setAccessible(true);
    return ctor.newInstance(iView);

   } catch (NoSuchMethodException e) {
    Constructor[] constructors = clazz.getDeclaredConstructors();
    for (Constructor c : constructors) {
     if (c.getParameterTypes().length > 1)
      continue;
     Class type = c.getParameterTypes()[0];
     if (type.isAssignableFrom(iView.getClass())) {
      return c.newInstance(type.cast(iView));
     }

    }
   }
   return null;

  } catch (Exception e) {
   e.printStackTrace();
   return null;
  }
 }
}

And run it again:

Object cls = instantiateClassNew("test.clazz.First",new FirstArg());
First f1 = (First) cls;
Object cls2 = instantiateClassNew("test.clazz.First",new SecondArg());
First f2 = (First) cls2;
System.out.println(f1.getArg().getClass());
System.out.println(f2.getArg().getClass());

Output:

FirstArg.FirstArg()
First() - constructor
FirstArg.FirstArg()
SecondArg.SecondArg()
First() - constructor
class test.clazz.FirstArg
class test.clazz.SecondArg

We should be careful when invoke methods via reflection with polymorphic arguments.

Overview: Optimistic vs. Pessimistic Locking

2011-10-09T23:17:00.000+02:00

Data Concurrency is a real problem in multi-user environment. How can we manage the data consistence when several users try to modify the same record(s) at the same time?
This is a very interesting subject. Mostly, it's compromise. We can't easily pick one approach and forget about another.
This subject was quite nice discussed in Martin's Fowler book: "Patterns of Enterprise Application Architecture"

And, you can find here the short Martin's overview: Pessimistic Offline Lock and Optimistic Offline Lock.

JBoss community documentation has nice quotes about the subject:

The disadvantage of pessimistic locking is that a resource is locked from the time it is first accessed in a transaction until the transaction is finished, making it inaccessible to other transactions during that time. If most transactions simply look at the resource and never change it, an exclusive lock may be overkill as it may cause lock contention, and optimistic locking may be a better approach. With pessimistic locking, locks are applied in a fail-safe way. In the banking application example, an account is locked as soon as it is accessed in a transaction. Attempts to use the account in other transactions while it is locked will either result in the other process being delayed until the account lock is released, or that the process transaction will be rolled back. The lock exists until the transaction has either been committed or rolled back.

With optimistic locking, a resource is not actually locked when it is first is accessed by a transaction. Instead, the state of the resource at the time when it would have been locked with the pessimistic locking approach is saved. Other transactions are able to concurrently access to the resource and the possibility of conflicting changes is possible. At commit time, when the resource is about to be updated in persistent storage, the state of the resource is read from storage again and compared to the state that was saved when the resource was first accessed in the transaction. If the two states differ, a conflicting update was made, and the transaction will be rolled back.

The most popular example of optimistic locking is SVN commit operation.

Java Code Quality Tools - Overview

2011-08-31T01:06:00.002+02:00

Recently, I had a chance to present the subject at the local IT community meetup. Here is the basic presentation:

Java Code Quality Tools

and more meaningful mind map:

But, I think I need to cover this subject more deeply. This blog post should be something like start point for further investigation in this direction.

1. CodePro Analytix
It's a great tool (Eclipse plugin) for improving software quality. It has the next key features: Code Analysis, JUnit Test Generation, JUnit Test Editor, Similar Code Analysis, Metrics, Code Coverage and Dependency Analysis.
2. PMD
It scans Java source code and looks for potential problems: Possible bugs, Dead code, Suboptimal code, Overcomplicated expressions and Duplicate code.
3. FindBugs
It looks for bugs in Java programs. It can detect a variety of common coding mistakes, including thread synchronization problems, misuse of API methods, etc.
4. Cobertura
It's a free Java tool that calculates the percentage of code accessed by tests. It can be used to identify which parts of your Java program are lacking test coverage. It is based on jcoverage.
5. Emma
It is a fast Java code coverage tool based on bytecode instrumentation. It differs from the existing tools by enabling coverage profiling on large scale enterprise software projects with simultaneous emphasis on fast individual development.
6. Checkstyle
It is a development tool to help programmers write Java code that adheres to a coding standard.
7. JBoss Tattletale
JBoss Tattletale is a tool that can help you get an overview of the project you are working on or a product that you depend on. The tool will recursive scan a directory for JAR files and generate linked and formatted HTML reports.
8. UCDetector
UCDetector (Unecessary Code Detector) is a Open Source eclipse PlugIn Tool to find unecessary (dead) java code. It also tries to make code final, protected or private. UCDetector also finds cyclic dependencies between classes.
9. Sonar
Sonar is a continuous quality control tool for Java applications. Its basic purpose in life is to join your existing continuous integration tools to place all your development projects under quality control.
10. XRadar
The XRadar is an open extensible code report tool that produces HTML/SVG reports of the systems current state and the development over time. Uses DependencyFinder, JDepend, PMD, PMD-CPD, JavaNCSS, Cobertura, Checkstyle, XSource, JUnit, Java2HTML, ant and maven.
11. QALab
QALab consolidates data from Checkstyle, PMD, FindBugs and Simian and displays it in one consolidated view. QALab keeps a track of the changes over time, thereby allowing you to see trends over time. You can tell weather the number of violations has increased or decreased - on a per file basis, or for the entire project. It also plots charts of this data. QALab plugs in to maven or ant.
12. Clirr
Clirr is a tool that checks Java libraries for binary and source compatibility with older releases. Basically you give it two sets of jar files and Clirr dumps out a list of changes in the public api. The Clirr Ant task can be configured to break the build if it detects incompatible api changes. In a continuous integration process Clirr can automatically prevent accidental introduction of binary or source compatibility problems.
13. JDiff
JDiff is a Javadoc doclet which generates an HTML report of all the packages, classes, constructors, methods, and fields which have been removed, added or changed in any way, including their documentation, when two APIs are compared. This is very useful for describing exactly what has changed between two releases of a product. Only the API (Application Programming Interface) of each version is compared. It does not compare what the source code does when executed.
14. JLint
It checks your Java code and find bugs, inconsistencies and synchronization problems by doing data flow analysis and building the lock graph.
15. JDepend
JDepend traverses Java class file directories and generates design quality metrics for each Java package. JDepend allows you to automatically measure the quality of a design in terms of its extensibility, reusability, and maintainability to effectively manage and control package dependencies.
16. cloc
cloc counts blank lines, comment lines, and physical lines of source code in many programming languages.
17. Dependometer
Dependometer performs a static analysis of physical dependencies within a software system. Dependometer validates dependencies against the logical architecture structuring the system into classes, packages, subsystems, vertical slices and layers and detects cycles between these structural elements. Furthermore, it calculates a number of quality metrics on the different abstraction layers and reports any violations against the configured thresholds.
18. Hammurapi
Hammurapi is an open source code inspection tool. Its release comes with more than 100 inspectors which inspect different aspects of code: Compliance with EJB specification, threading issues, coding standards, and much more.
19. JavaNCSS

JavaNCSS is a simple command line utility which measures two standardsource code metrics for the Java programming language. The metrics arecollected globally, for each class and/or for each function.
20. DCD
DCD finds dead code in your Java applications.
21. Classycle
Classycle's Analyser analyses the static class and package dependencies in Java applications or libraries. It is especially helpful for finding cyclic dependencies between classes or packages. Classycle is similar to JDepend which does also a dependency analysis but only on the package level.
22. ckjm
The program ckjm calculates Chidamber and Kemerer object-orientedmetrics by processing the bytecode of compiled Java files.The program calculates for each class the following six metrics proposedby Chidamber and Kemerer.
23. Jameleon
Jameleon is an automated testing framework that can be easily used by technical and non-technical users alike. One of the main concepts behind Jameleon is to create a group of keywords or tags that represent different screens of an application. All of the logic required to automate each particular screen can be defined in Java and mapped to these keywords. The keywords can then be organized with different data sets to form test scripts without requiring an in-depth knowledge of how the application works. The test scripts are then used to automate testing and to generate manual test case documentation.
24. DoctorJ
DoctorJ analyzes Java code, in the following functional areas: documentation verification, statistics generation and syntax analysis.
25. Macker
Macker is a build-time architectural rule checking utility for Java developers. It's meant to model the architectural ideals programmers always dream up for their projects, and then break -- it helps keep code clean and consistent. You can tailor a rules file to suit a specific project's structure, or write some general "good practice" rules for your code. Macker doesn't try to shove anybody else's rules down your throat; it's flexible, and writing a rules file is part of the development process for each unique project.
26. Squale
Squale is a qualimetry platform that allows to analyze multi-language software applications in order to give a sharp and comprehensive picture of their quality: High level factors for top-managers and Practical indicators for development teams.
27. SourceMonitor
The freeware program SourceMonitor lets you see inside your software source code to find out how much code you have and to identify the relative complexity of your modules. For example, you can use SourceMonitor to identify the code that is most likely to contain defects and thus warrants formal review.
28. Panopticon
The Panopticode project provides a set of open source tools for gathering, correlating, and displaying code metrics.
29. Eclipse Metrics plugin

Provide metrics calculation and dependency analyzer plugin for the Eclipse platform. Measure various metrics with average and standard deviation and detect cycles in package and type dependencies and graph them.
30. QJ-Pro
QJ-Pro is a comprehensive software inspection tool targeted towards the software developer. Developers can automatically inspect their Java source code and improve their Java programming skills as they write their programs. QJ-Pro provides descriptive Java patterns explaining error prone code constructs and providing solutions for it.
31. Byecycle
Byecycle is an auto-arranging dependency analysis plugin for Eclipse. Its goal is to make you feel sick when you see bad code and to make you feel happy when you see good code.
32. Coqua
Coqua measures 5 distinct Java code quality metrics, providing an overview and history for the management, and down-to-the-code, detailed views for the developer. Metrics can be defined per team. Ideal for mid- to large-sized and/or offshore projects.
33. Dependency Finder
Extracts dependencies and OO metrics from Java class files produced by most Java compilers.
34. Jalopy
Jalopy is an easily configurable source code formatter that can detect, and fix, a number of code convention flaws that might appear in Java code. Jalopy is more of a code fixer than a code checker. Jalopy plug-ins are present for most IDEs and, in most cases, they gel quite seamlessly with the IDE.
35. JarAnalyzer
JarAnalyzer is a dependency management tool for .jar files. JarAnalyzer will analyze all .jar in a given directory and identify the dependencies between each. Output formats include xml, with a stylesheet included to transform it to html, and GraphViz DOT, allowing you to produce a visual component diagram showing the relationships between .jar files. The xml output includes important design metrics such as Afferent and Efferent coupling, Abstractness, Instability, and Distance. There is also an Ant task available that allows you to include JarAnalyzer as part of your build script.
36. Condenser
Condenser is a tool for finding and removing duplicated Java code. Unlike tools that only locate duplicated code, the aim of Condenser is to also automatically remove duplicated code where it is safe to do so.
37. Relief
Relief provides a new look on Java projects. Relying on our ability to deal with real objects by examining their shape, size or relative place in space it gives a "physical" view on java packages, types and fields and their relationships, making them easier to handle. Lets discuss quickly how we interprete physical properties and how it can help us to grasp project characteristics.
38. JCSC
JCSC is a powerful tool to check source code against a highly definable coding standard and potential bad code. The standard covers naming conventions for class, interfaces, fields, parameter, ... . Also the structural layout of the type (class/interface) can be defined. Like where to place fields, either before or after the methods and in which order. The order can be defined through the visibility or by type (instance, class, constant). The same is applicable for methods. Each of those rules is highly customizable. Readability is enhanced by defining where to put white spaces in the code and when to use braces. The existence of correct JavaDoc can be enforced and various levels. Apart from that, it finds weaknesses in the the code -- potential bugs -- like empty catch/finally block, switch without default, throwing of type 'Exception', slow code.
39. Spoon
Spoon is a Java program processor that fully supports Java 5. It provides a complete and fine-grained Java metamodel where any program element (classes, methods, fields, statements, expressions...) can be accessed both for reading and modification. Spoon can be used on validation purpose, to ensure that your programs respect some programming conventions or guidelines, or for program transformation, by using a pure-Java template engine.
40. Lint4j
Lint4j ("Lint for Java") is a static Java source and byte code analyzer that detects locking and threading issues, performance and scalability problems, and checks complex contracts such as Java serialization by performing type, data flow, and lock graph analysis.
41. Crap4j
Crap4j is a Java implementation of the CRAP (Change Risk Analysis and Predictions) software metric – a mildly offensive metric name to help protect you from truly offensive code.
42. PathFinder
Java PathFinder (JPF) is a system to verify executable Java bytecode programs. In its basic form, it is a Java Virtual Machine (JVM) that is used as an explicit state software model checker, systematically exploring all potential execution paths of a program to find violations of properties like deadlocks or unhandled exceptions. Unlike traditional debuggers, JPF reports the entire execution path that leads to a defect. JPF is especially well-suited to finding hard-to-test concurrency defects in multithreaded program
43. Soot
Soot can be used as a stand alone tool to optimize or inspect class files, as well as a framework to develop optimizations or transformations on Java bytecode.
44. ESC/Java2
The Extended Static Checker for Java version 2 (ESC/Java2) is a programming tool that attempts to find common run-time errors in JML-annotated Java programs by static analysis of the program code and its formal annotations. Users can control the amount and kinds of checking that ESC/Java2 performs by annotating their programs with specially formatted comments called pragmas.

* * *

This list includes open sourced and free tools. I intentionally have excluded commercial tools. I'm sure there are much more tools. In case your know some of them which isn't listed here please add comment to this post.

My reflection on "Programming Achievements: How to Level Up as a Developer"

2011-08-14T23:52:00.003+02:00

Recently, I've read an amazing blog post "Programming Achievements: How to Level Up as a Developer". Also, it worth to read comments to this post, they are really interesting, subjective and personal. But, in any case you'll get something to think about. How to measure your own professional achievements, different ways for improvements and some start point for planning all these stuff.

The author suggests to use GitHub Gist as a natural way of improvements to keep them tracking. So, I've just forked his gist and performed several initial changes (see https://gist.github.com/1141765):

IT Booze Meetup #2: Scala, Clojure, Groovy

2011-07-30T15:11:00.002+02:00

Today, I had a chance to attend local user group IT Booze. It was the second meetup and it was very interesting, because of topics which were under discussion: Scala, Clojure And Groovy. I love such events especially in my town. :-)

I'd like to share my reflections regarding these cool languages.

As you know these languages are very popular on JVM (of cause not so popular as Java :-). And I'm sure every passionate Java/JVM developer has been thinking "what's the Next Big Language". It's really hard to choose the next one.

So, here is a short "brain snapshot":

Scala and Clojure are great languages with huge amount of interesting features, but to master them we need to use Scala (or Clojure) on daily basis.
Scala appeared as complex language. I think it requires a steeper learning curve then Clojure or Groovy. It means we must invest much, much more.
Clojure has lisp syntax, but innovative concurrency concept is worth to look into. I say lisp, because it might be a stopper for someone to evaluate it as a next big language.
Clojure and functional programming require to "patch" our way of thinking. And it can be difficult.
Groovy is agile language. We (Java developers) can start using it right away. I think we should invest more in Groovy just to boost our productivity in: scripting, testing, automation routine work, etc. It doesn't require big investments and we can learn as we go.

So, here is outcome from this meetup:

start using Groovy
look into Clojure concepts
postpone Scala for now

Could you please share your thoughts regarding this?

How to disable System.out?

2011-07-20T22:29:00.001+02:00

I have a legacy code base with tons of System.out.println(). Actually, I don't need this in production, but during development it's cool enough to have. So, I've decided to disable System.out:

package org.halyph;

import java.io.OutputStream;
import java.io.PrintStream;

public class DisableMain {
	public static void main(String[] args) {
		PrintStream printStreamOriginal = System.out;

		boolean DEBUG = true;
		if (!DEBUG) {
			System.setOut(new PrintStream(new OutputStream() {
				public void close() {}
				public void flush() {}
				public void write(byte[] b) {}
				public void write(byte[] b, int off, int len) {}
				public void write(int b) {
				}
			}));
		}

		long a = System.currentTimeMillis();
		for (int i = 0; i < 1000000; i++) {
			System.out.println("Hello");
		}

		long b = System.currentTimeMillis() - a;

		System.setOut(printStreamOriginal);
		System.out.println(b);
	}
}

So, plain looped println required ~10 seconds on my laptop, and only ~1 second with null output stream.

Ubuntu Server 10.04.2 VM Basic Configuration

2011-07-19T00:45:00.002+02:00

+ +

Required tools:

VMware Worstation
Ubuntu Server 10.04.2
Kitty (Putty ssh client fork)

I suppose that You know how to setup plain VM via VMware.
And here is my basic Ubuntu VM configuration:

Ubuntu Server 10.04.2 doesn't include SSH server by default. That's why you have to install it:

sudo apt-get install ssh

Check your Ubuntu VM IP:

$ ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0c:29:04:55:d6
          inet addr:192.168.11.134  Bcast:192.168.11.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe04:55d6/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:50 errors:0 dropped:0 overruns:0 frame:0
          TX packets:52 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:6303 (6.3 KB)  TX bytes:7366 (7.3 KB)
          Interrupt:19 Base address:0x2000

Configure Kitty connection host name:
Create two scripts for:

startup VM in background (start_vm.bat)

set MYVM="F:\VMs\ubuntu-10.04.2-server\Ubuntu Server 10.04.2.vmx"
set VMRUN="E:\Program Files\VMware\VMware Workstation\vmrun"

%VMRUN% -T ws start %MYVM% nogui

shutdown VM (stop_vm.bat)

set MYVM="F:\VMs\ubuntu-10.04.2-server\Ubuntu Server 10.04.2.vmx"
set VMRUN="E:\Program Files\VMware\VMware Workstation\vmrun"

%VMRUN% stop %MYVM% soft

Configure Kitty for auto-login:
VM startup and Kitty run can be combined into one script

Clojure Books

2011-07-11T22:00:00.001+02:00

Published

Books which aren't fully dedicated to Clojure

Coming Soon (in progress)

How to Add Jars at Runtime?

2011-06-28T13:34:00.000+02:00

Suppose you have the next project structure:

Here is the source code:

package org.halyph.one;

import java.io.File;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.CodeSource;

import org.halyph.three.MyClassThree;
import org.halyph.two.MyClassTwo;

public class DynamicClassLoader {
 public static void main(String[] args) throws Exception {
  System.out.println("DynamicClassLoader.main()");

  MyClassTwo myClassTwo = new MyClassTwo();
  MyClassThree myClassThree = new MyClassThree();
  myClassTwo.printMessage();
  myClassThree.printMessage();

 }
}

package org.halyph.two;

public class MyClassTwo {
 public void printMessage() {
  System.out.println("MyClassTwo.printMessage()");
 }
}

package org.halyph.three;

public class MyClassThree {
 public void printMessage() {
  System.out.println("MyClassThree.printMessage()");
 }
}

And each of these classes are packed in separate jar:

org.halyph.one.DynamicClassLoader - dynone.jar
org.halyph.two.MyClassTwo - dyntwo.jar
org.halyph.three.MyClassThree - dynthree.jar

To run this application you should put all these jars on classpath,
E.g. the application output

# java -cp dynone.jar;dyntwo.jar;dynthree.jar org.halyph.one.DynamicClassLoader
DynamicClassLoader.main()
MyClassTwo.printMessage()
MyClassThree.printMessage()

But there are some cases when dyntwo.jar and dynthree.jar jars location can be known during runtime only. And we have to run our application in the next way:

# java -cp dynone.jar org.halyph.one.DynamicClassLoader

Of cause, you'll get the next (or similar) error:

# java -cp dynone.jar org.halyph.one.DynamicClassLoader
DynamicClassLoader.main()
Exception in thread "main" java.lang.NoClassDefFoundError: org/halyph/two/MyClassTwo
        at org.halyph.one.DynamicClassLoader.main(DynamicClassLoader.java:28)
Caused by: java.lang.ClassNotFoundException: org.halyph.two.MyClassTwo
        at java.net.URLClassLoader$1.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        ... 1 more

So, how can we solve this problem?
Here is the patched org.halyph.one.DynamicClassLoader:

package org.halyph.one;

import java.io.File;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.CodeSource;

import org.halyph.three.MyClassThree;
import org.halyph.two.MyClassTwo;

public class DynamicClassLoader {

 public static void main(String[] args) throws Exception {
  System.out.println("DynamicClassLoader.main()");

  String[] jars = new String[] { "dyntwo.jar",  "dynthree.jar"};
  addJarsToClasspath(getRootFolder(), jars);
  MyClassTwo myClassTwo = new MyClassTwo();
  MyClassThree myClassThree = new MyClassThree();
  myClassTwo.printMessage();
  myClassThree.printMessage();

 }

 public static void addJarsToClasspath(String rootFolder, String[] jarNames)
   throws SecurityException, NoSuchMethodException,
   MalformedURLException, IllegalArgumentException,
   IllegalAccessException, InvocationTargetException {

  Method addURL = URLClassLoader.class.getDeclaredMethod("addURL",
    new Class[] { URL.class });
  addURL.setAccessible(true); // you're telling the JVM to override the
         // default visibility

  File[] files = new File[jarNames.length];
  int i = 0;
  for (String jarName : jarNames) {
   files[i++] = new File(rootFolder + jarName);
  }

  // returning the jars to add
  ClassLoader cl = ClassLoader.getSystemClassLoader();
  for (i = 0; i < files.length; i++) {
   URL url = files[i].toURL();
   addURL.invoke(cl, new Object[] { url });
  }
 }

 public static String getRootFolder() {
  String result = null;
  try {
   String qualifiedClassName = DynamicClassLoader.class.getName();

   Class qc = Class.forName(qualifiedClassName);
   CodeSource source = qc.getProtectionDomain().getCodeSource();
   if (source != null) {
    URL location = source.getLocation();
    File file = new File(location.toURI());

    result = file.getParent() + "/";
   } else {
    System.out.println(qualifiedClassName + " : "
      + "unknown source");
   }
  } catch (Exception e) {
   System.err.println("Unable to locate class on command line.");
   e.printStackTrace();
  }
  return result;
 }

}

Here is the output of patched application:

# java -cp dynone.jar org.halyph.one.DynamicClassLoader
DynamicClassLoader.main()
MyClassTwo.printMessage()
MyClassThree.printMessage()

So, two additional methods were added to support this "magic":

public static String getRootFolder()- this method simply identifies the folder where dynone.jar (on behalf of org.halyph.one.DynamicClassLoader class) is located. Because for this demo we put all application-related jars in one folder
public static void addJarsToClasspath(String rootFolder, String[] jarNames) - and here the "magic" happen. Based on this post on www.velocityreviews.com forums:

There is a well-known hack for dynamically extending the class path.
It generally works, and we use it in production releases of our software. It uses reflection, plus the knowledge that the default ClassLoader *is* a URLClassLoader.
...
As I said, this is a hack, undocumented, and subject to change at any
time. Indeed, there's no guarantee that extant JREs use a URLClassLoader as a default class loader. Moreover, it only works if your program doesn't have a security manager (it probably doesn't), or your code is trusted.
...
We've never seen problems with it, although our software is used on a plethora of different boxes and OSs.

It works for me and I hope it will be useful for you as well.
Happy hacking!

@Override Java Annotation Issue

2011-06-19T23:55:00.000+02:00

Let's create one simple interface and class which implements this interface:

public interface IOverride {
    void doSomething();
}
public class Overridden implements IOverride {
    @Override
    public void doSomething() {
    }
}

And compile this stuff on JDK v.1.5:

# javac -d classes src\*.java
src\Overridden.java:2: method does not override a method from its superclass
        @Override
         ^
1 error

Let's try to do the same on JDK v.1.6 - And, You've got no compilation error.

Between Java 5 and Java 6 changes to the specification of @Override have been made. In Java 6 it is possible to add the @Override annotation to methods that implement methods of an interface which is not allowed in Java 5. (http://dertompson.com/2008/01/25/override-specification-changes-in-java-6/)

Also, I've found very interesting discussion on Stackoverflow: http://stackoverflow.com/questions/94361/when-do-you-use-javas-override-annotation-and-why:

Q:

What are the best practices for using Java's @Override annotation and why?
It seems like it would be overkill to mark every single overridden method with the @Override annotation. Are there certain programming situations that call for using the @Override and others that should never use the @Override?

Use it every time you override a method for two benefits. Do it so that you can take advantage of the compiler checking to make sure you actually are overriding a method when you think you are. This way, if you make a common mistake of misspelling a method name or not correctly matching the parameters, you will be warned that you method does not actually override as you think it does. Secondly, it makes your code easier to understand because it is more obvious when methods are overwritten.

Additionally, in Java 1.6 you can use it to mark when a method implements an interface for the same benefits. I think it would be better to have a separate annotation (like @Implements), but it's better than nothing.

ITEvent 2011, Local Conference – Report

2011-06-12T01:28:00.000+02:00

Yesterday (June 11, 2011) I attended the local (Ivano-Frankivsk, Ukraine) IT related conference “itEvent 2011”. I must say I am impressed. There were more than a hundred participants. And it’s amazing. We live in a very small city and this local event/conference waked up so many developers to attend this event.

The conference had three parallel flows/stages. And it’s a good sign. The organizers give us a chance to choose the most preferable topic(s) to attend. Additional good point is that each presentation was shot on video. So, I could see missed interesting topics.

Here is the talks (which I saw and hear) overview:

1. “Two sides of IT interview” by Nataliya Mukhitdunova. To tell the truth I wasn’t expected that such boring subject can be presented in such interesting way. Just wow. The speaker was concentrated on two interview stakeholders: HR and Developer. She clearly defined their goals and expectations, tips for HRs (as interviewer) and for Developers (as interviewee). And this speech was so easy made and “light” that I felt “I’m in right place in right time”. The presenter doesn’t use any slides or other supportive material, she was just well prepared with good background in this area.

2. “Kanban and the creation of the high effective teams” by Sergiy Fitsak and Anatoliy Okhotnikov. I’ve expected to hear some advices, case studies (especially BAD experience) and of cause the process implementation issues. And I’ve got all these. Thanks to the presenters. The one “minus” was that this talk wasn’t well coordinated between two presenters and they overused the presentation’s time limit. They hadn't predicted that they got so many questions and discussions. I can say that this talk really revived the audience. And it was cool.

3. “Facebook as a mobile application platform” by Yevgen Vershynin. The presenter showed us from the very begging what the Facebook platform is and how to use it. This area was absolutely new for me. Additionally, he was well prepared and his speech was very dynamic. And, even more, he showed some passion during the speech. That’s why it was so interest. I must admit that Yevgen (the presenter) showed very high presentation, communication skills, and good domain knowledge. Very impressive.

4. “How to meet customer expectations” by Ruslan Seredyuk. This topic was absolutely new for me. I mean I’ve never thought about “customer expectations” and “what is the successful project”. I like to discover something new. The presenter showed real knowledge which is based on work experience. And it’s very important. Every single case in his presentation had small life sample, which was very useful to demonstrate the all dark places in this mess area (i.e. customer expectations). Again, the presenter was well prepared with real case studies. The one "minus" is that the target audience wasn’t mentioned. And this topic wasn’t dedicated for the junior developers, IMHO.

Now, let’s talk about conference organizations:

Pros:

1. There were a lot of coffee, cakes and water.

2. The registration was straightforward.

3. The atmosphere was VERY friendly.

4. The presentations' quality was good.

5. And the most important, the itEvent organizer overdid their own expectation, they gathered huge amount of IT related people in one place and gave them a chance to talk to each other and share personal knowledge, vision and contacts. As for me, the goal was perfectly achieved.

Cons:

1. I think that Conference, Camp or similar event should have some motto.

2. It’s good to have agenda for every presentation/speech in English as well

3. It’s good to have target audience for every presentation/speech. It’s even more important in multi-target conference (here we can see management, technical and usability directions, etc.)

4. The conference’s web resource is in Ukrainian only. It’s good to have English as well. Also, the web resource structure could be improved.

So, the overall impression is good. This local conference exceeded my expectations. I hope we’ll have the similar event next year.

Top 15 Java Web Resources

2011-06-06T00:41:00.003+02:00

Here is the top 15 Java-related resources I'd like to share with you.

Blogs, News aggregator

	1. http://www.dzone.com is a very big aggregator for news, articles, video interviews, tutorials, reviews, and announcements. Also, you can use some particular, dedicated "zones": http://java.dzone.com - Javalobby IDEs and Tools: http://eclipse.dzone.com http://jetbrains.dzone.com http://netbeans.dzone.com This resource contains huge amount of information and you could easily lost there (50-80 new items per day). So, I suggest to use Javalobby as a start point.
	2. http://www.infoq.com News, videos, interviews, conference reports, etc.
	3. http://www.java.net Articles, blogs, wiki, news.

Forums and Q&A

	4. http://www.javaranch.com is one of the biggest Java forum
	5. http://stackoverflow.com it's one of the biggest Q&A site which includes such features as Q&A, forum, wiki, blog, collaboration and community based content moderation.

Videos

	6. http://www.java-tv.com Java-TV.com is a directory of videos, interviews and tutorials focused on software development activities with the Java™ programming language.
	7. http://www.softdevtube.com SoftDevTube is a repository of videos, interviews and tutorials focused on all software development activities.

Cookbooks

	8. http://www.discursive.com/book/322 Common Java Cookbook This collection provides expert tips for using Java-based utilities from projects such as Apache Commons, Apache Lucene, and Apache Velocity. You don't have to be an expert, the book's solution-based format contains code examples for a wide variety of web, XML, network, testing, and application projects. If you want to learn how to combine common open-source Java utilities to create powerful Java applications and tools, the Common Java Cookbook is for you.
	9. http://mindprod.com/jgloss/jgloss.html Canadian Mind Products Java & Internet Glossary
	10. http://www.javapractices.com/home/HomeAction.do Collected Java Practices. It offers concise presentations of Java practices, tasks, and designs, illustrated with syntax-highlighted code examples.
	11. http://www.leepoint.net/notes-java/index.html Java Notes. These Java programming notes are written to fill in missing or weak topics in textbooks the Author has taught from.
	12. http://www.javamex.com Javamex is the author attempt to gather together information on some of the more intricate aspects of Java programming, building on the experience with the language.
	13. http://www.exampledepot.com This site holds all the examples from The Java Developers Almanac and more. Copy and paste these examples directly into your applications. Over a thousand useful examples can be found there.

Other

	14. http://javatoolbox.com JavaToolbox.com references the tools you need for Java development.
	15. http://www.blackbeltfactory.com On-line community-based exam system

How to choose between Scala and Clojure?

2011-06-01T00:55:00.003+02:00

vs.

I think it's very popular question nowadays. The Java-haters produce so many buzz around this. So, want you or not, but You passively have been trying to choose the Java.next().

I've found several interesting posts which cover pretty much about this subject:
by Stephan Schmidt

by Lau B. Jensen

Others

Hint: Try to read comments to these posts, there are very interesting discussions. Some of them are even more useful than the actual post(s)/article(s).

These articles don't give you any advices or strong opinions which language is the best. But, it's a good start point, for sure.

JEEConf - Kiev, 2011 - Report

2011-05-23T23:41:00.002+02:00

I had a chance to attend the first and totally dedicated to Java conference in Kiev (May 21, 2011).
It was a great. The atmosphere was amazing. The organization was good, really good. The most noticeable thing was that almost every presentation was based on real problem, no metaphysical stuff :-)
There were three stages, that's why I couldn't attend every talk and that's a pity.

Here is a short overview of all attended talks:

1. "What Riding the Camel can do to make integration easier for you" by Claus Ibsen.
I had an idea what the Camel is, but this presentation gave me the "big picture". Actually, the speaker has been well prepared and known the presentation technique very well. He showed all major aspects of Camel framework and explain its purpose.

He's shown the several Camel's DSLs: XML-based, Java and Scala. That short code snippets were really cool and clean. So, I've added into my todo list "the Camel DSL digging" ;-)

2. "The Scala and GridGain usage for the distributed systems with high efficiency" by Renat Ahmerov.
This talk and master-class inspired me to start Scala learning. I've never seen the cloud computing in action. But during that master-class was created real application for distributed computing. And the code base was so tiny and clean, so my heart falling in love to this language. The last time I had had the similar feeling when I've seen the Rails in action.

3. The problem diagnosing and GC tuning in HotSpot Java VM by Vladimir Ivanov.
This talk was like a JVM magic :-). The speaker discovered the darkest GC places I've never known about. He's opened my eyes. I even couldn't expect that GC tuning is so interesting.

4. To be in ten times faster kudos Groovy by Evgeny Kompaniec
This guy has shown the real case study:
- Why he choose the Groovy as Java substitution.
- Java code snippets vs Groovy (functionally equal) code snippets. IMHO, the most interesting and inspiration part of talk.
- Groovy knowledge sharing via pros & cons.

5. Unitils for Java testing by Mikalai Alimenkou
To be honest I've never heard about this tools. This presentation was full of practical samples and advices like a cookbook. Great talk, the presenter had a good mood and used the right jokes in the right places, he was very impressive. I wish every speaker had such good presentation technique.

6. How Graph Databases can make you a super star by Andrés Taylor
This talk was dedicated to the "beauty" of Neo4j graph DB. It was just a start point for this DB.

7. Vaadin, Rich Web Apps in Server-Side Java without Plug-ins or JavaScript by Joonas Lehtinen
I've been following this framework about a year. And I must admit that it was really impressed to see CEO of company behind Vaadin.
The talk was short and pragmatic. The major areas of Vaadin were highlighted. Then, the presenter has shown the Vaadin in action and it was cool. The community and the whole framework evolved in one year. As for me it was great to see the real person who developed so interesting stuff.

It was my 6th IT conference. I must admit it was the best, no doubts. I hope to attend the Java conference next year again.

XP, Scrum and Kanban: How to make the first step?

2011-05-03T00:28:00.001+02:00

There are so many books, articles and blog posts about the topic. And it's not the easy way to chose the right one, laconic and simple, with pragmatic advices and some real case studies.
The biggest issues for almost every "agile" related book is their size, about 300 pages (in general). But what about brief, all-sufficient book?
I can suggest two, short enough, books: Scrum and XP from the Trenches and Kanban and Scrum - making the most of both. The names of the books are self-explained.

You've got the "big picture" after the reading of these books.

Axis2 and Tomcat work together with SecurityManager

2011-04-16T23:57:00.001+02:00

First of all download the latest Tomcat and axis2.war.
Read Tomcat Security Manager HOW-TO
Setup Tomcat and deploy axis2.war.
Edit <TOMCAT install dir>/conf/catalina.policy file and add the next:

grant {
    permission java.io.FilePermission "${catalina.base}/webapps/axis2/WEB-INF/-", "read";
    permission java.lang.RuntimePermission "getClassLoader";
}

grant codeBase "file:${catalina.home}/webapps/axis2/-" {
    permission java.lang.RuntimePermission "createClassLoader";  
    permission java.lang.RuntimePermission "setContextClassLoader";  
    permission java.lang.RuntimePermission "checkPropertiesAccess";  
    permission java.lang.RuntimePermission "getClassLoader";  
    permission java.lang.RuntimePermission "getProtectionDomain";  
    permission java.lang.RuntimePermission "defineClassInPackage.org.apache.jasper.runtime";  
    permission java.lang.RuntimePermission "accessClassInPackage.org.apache.catalina.deploy";
    permission java.lang.RuntimePermission "shutdownHooks";  
    permission java.lang.RuntimePermission "accessDeclaredMembers";  
    permission java.util.PropertyPermission "*", "read,write";  
    permission java.net.SocketPermission "localhost:8080", "resolve, connect";  
    permission java.io.FilePermission "${catalina.base}/webapps/axis2/WEB-INF/modules/*", "read,write";  
    permission java.io.FilePermission "${catalina.base}/webapps/axis2/WEB-INF/services/*", "read,write";  
    permission java.io.FilePermission "${catalina.home}/common/classes", "read";  
    permission java.io.FilePermission "${catalina.home}/shared/classes", "read";  
    permission java.io.FilePermission "${catalina.base}/common/classes", "read";  
    permission java.io.FilePermission "${catalina.base}/shared/classes", "read";  
    permission java.io.FilePermission "${catalina.home}/common/i18n/*", "read";  
    permission java.io.FilePermission "${catalina.home}/common/lib/*", "read";  
    permission java.io.FilePermission "${catalina.home}/lib", "read";  
    permission java.io.FilePermission "${catalina.home}/lib/*", "read";  
    permission java.io.FilePermission "${catalina.home}/bin/*", "read";  
    permission java.io.FilePermission "${catalina.base}/webapps/axis2/WEB-INF/scriptServices/*", "read";  
    permission java.io.FilePermission "${java.home}/lib/ext/*", "read";  
    permission java.io.FilePermission "${catalina.base}/webapps/axis2/WEB-INF/web.xml", "read";  
    permission java.io.FilePermission "${java.io.tmpdir}${/}-", "read, write, delete"; 
    permission java.io.FilePermission "${java.io.tmpdir}", "read, write, delete";
};

Start Tomcat with SecurityManager:

$CATALINA_HOME/bin/catalina.sh start -security    (Unix)
%CATALINA_HOME%\bin\catalina start -security      (Windows)

Verify axis2 "HappyAxis" page as follows: http://localhost:8080/axis2/axis2-web/HappyAxis.jsp

NOTE: other application servers can and have different security policy file options/permissions.

Lisp Balkanization?

2011-02-15T01:02:00.001+02:00

I've heard this words' pair too often and I never knew what does it mean?

Until I read these two posts: Ultra-Balkanization Makes Lisp Autistic and Reddit and Lisp psychosis.

In general every Lisp developer tends to write "new" super-puper Lisp, invent the wheel, write own "cool" emacs extension and tell to the world that he is a HACKER. I love this.

Nowadays, Clojure is the real answer for Lisp guys. It can consolidate the Lisp language flexibility and JVM power. I think it's a good choice.

How to choose the next programming language to learn?

2011-02-11T00:50:00.003+02:00

I believe that this question has been appearing in the brains very often.
Note: I'm writing from Java developer point of view.

How to solve this dilemma? I said "dilemma" because it's investment in the new knowledge. And every new knowledge should bring some benefits. The wrong investment is equal to waste of your time.

As a Java developer I think I should invest outside the JVM. It's even more important in nowadays. Oracle is more aggressive then Sun was. So, investment in non-JVM "platform"/language can protect the own future.

I don't want to write about some definite language. It's not important right now. The most important thing is to learn something new which is totally separated from JVM.

Someone can say: "Try Groovy, Scala or Clojure". Good point. But, it's JVM (even if they are "beautiful" and interesting choices). One exception: you can have a possibility to use these languages on the job project. In that case it's ok. Just pick the right one and start the party. In other case avoid them.

There is NO right answer. Just define your own philosophy (language to learn) and keep it alive.

Review: Language Grubbing

2011-01-26T02:58:00.005+02:00

Yet another interesting reading from Steve Yegge: Language Grubbing.

He reviewed several programming languages (C, C++, Java, Perl, Python, Ruby, Smalltalk, Lisp family, ML family, Haskell, Erlang). He mentioned pros and cons for each of them, criticized some of them (Perl, Common Lisp). Also told that Lua, Tcl, Prolog, Pascal wouldn't be in his learning "backlog".

I looked at a lot of other languages: JavaScript, Lua, Tcl, Prolog, Eiffel, Pascal, and a bunch of others. None of them really stood out as being "special" like the others I've talked about.

For instance, you can do Prolog-like logic/constraint programming in Lisp or OCaml pretty easily, and they're both broader/better languages than Prolog. Pascal gives you nothing that C doesn't already do better. ... Lua is a cleaned-up Tcl, but neither one of them is as interesting (to me, anyway) as Python for doing embedded languages, unless you really need to strip it down to practically nothing, in which case Lua is useful.

IMHO, reasonable comments.
He mentioned about language groups:

Java, C# and C++ (I would add Objective-C and Smalltalk)
Haskell, SML, OCaml (I would add F#, Scala)
Common Lisp, Emacs Lisp, Scheme (I would add Clojure)
Perl, Python, Ruby (I would add PHP)
Erlang (I would add Prolog, Oz)
Lua, Tcl, JavaScript (I would add Io, Ioke, R, REBOL)
C, Pascal

I wrote about this but I'll repeat again. I time wasting if you learn several languages from the same group. E.g. Python and Ruby, or Java and C#.
So, just a pick the "major" language from each group and learn it. E.g.: Java, Haskell, Clojure, Ruby, JavaScript and C.

C language is like Latin for the plain developer. JavaScript is must be know by anyone involved in web-related development.

For myself I formed the next language priority list:

Java
JavaScript
Ruby or Python (I haven't decided yet)
Clojure, Scheme or Common Lisp (I haven't decided yet)
C

Review: Beating the Averages

2011-01-25T01:08:00.001+02:00

This Paul's Graham essay (Beating the Averages) is very popular among Lisp community. Someone told that it was the new Lisp push, the new Lisp wave. I read this essay and companion technical article "Lisp in Web-Based Applications" in one short. It's really inspired reading.

Paul Graham described the "hidden" power of Lisp. Unfortunately, the Common Lisp community is fragmented so much. Too many different implementations. It hurts Lisp as a sub-culture. I hope this situation will be resolved by Clojure vibrant community

Definitely, if you want to open your Lisp mind you should read this essay. Nothing special from technical point of view, but really cool as Lisp catalyst. Read it, feel the power, feel the spirit.

The general idea (IMHO): startup is the right place to try something new and revolutionary to "kill" your competitors.

Lisp, Ruby, Acceptable and not Acceptable

2011-01-22T17:10:00.001+02:00

There is one really (in)famous essay Why Ruby is an acceptable LISP by Eric Kidd. The most interesting of all this stuff are comments and other responsive blog posts (e.g. Lisp is Not an Acceptable Lisp by Steve Yegge)
I can say this is something like "vs" essay which is very popular nowadays.

Here is the list of some quotes and key ideas:

Lisp macros are far more powerful than the trivial use cases you’ve listed. I could give a lot of examples here, but just ask yourself: why is most of the programming community so fond with “Design Patterns”, while the Lisp community generally isn’t? Well, that’s because patterns are nothing but high-level specifications for code being rewritten again and again and again. The Lisp approach is to create some macros and auxiliary functions that actually implement the pattern, thus extending the language capabilities and avoiding continuous reinvention of the wheel.
This article sounds like it was written for folks who really want to use Lisp, but have chosen Ruby because all the cool kids are using it and want to reasonably justify an emotional decision.
If you want to learn a language that can change with the times and incorporate whatever latest fad the programming cool kids have to offer, Lisp is the choice. Lisp is the red pill.
A final example: look at the 2 open source Computer Algebra Systems written in Common Lisp available as Open Source: 1) Axiom – originally from IBM Thomas Watson Research Center; 2) Maxima – originally Department of Energy (US). This is software written in the 70s. You can’t write software that lasts so long with a language that is a moving target. This is the kind of survival and complex domain which shows the power of Lisp.
The real reason that brought me to Lisp (and never will get me away from it) is simply this:
You can build it out of 7 (s-e-v-e-n) primitive operators!
And, as a consequence, no other language can be expressed in itself as short as Lisp. (As you probably know, quite any language can be expressed in itself.)
So let me repeat: really no other language can be expressed in itself that short, and (as a natural consequence) can be built out of less primitive operators.
Ruby has a syntax, and Ruby needs a full parser to get from that syntax to an AST. Because Lisp code is naturally an AST, things are very different

And small summary of the Steve's blog post Lisp is Not an Acceptable Lisp:

There is no acceptable Lisp. This is a problem. It's not a little teeny one, either. The Lisp communities (yeah, there are a bunch) are going to have to realize that if Lisp is ever going to be massively successful, it needs an overhaul. Or maybe a revolution. Contrary to what some might tell you, it doesn't need a committee, and it doesn't need a bunch of money. Linux proved exactly the opposite. Lisp needs a benevolent dictator. Lisp needs to ditch the name "Lisp", since it scares people. And Lisp needs to learn from the lessons of the 45 years of languages that have followed it.

Based on this comments and I'm attaching this funny picture:

The programmer's superiority complex... in hierarchy format.

Review: You Should Write Blogs?

2011-01-14T01:56:00.001+02:00

I've just finished reading the Steve Yegge's post "You Should Write Blogs".
As for me it's very impressive and honest writing about blogging I've ever read. I like this style of writing.
The general idea is to explain why You should write blogs.

So don't worry about whether people will read it. Just write it!

No matter where you are in your education, some people will be interested in hearing your struggles. This is an important thing to keep in mind when you're blogging. Each person in your audience is on a different clock, and all of them are ahead of you in some ways and behind you in others. The point of blogging is that we all agree to share where we're at, and not poke fun at people who seem to be behind us, because they may know other things that we won't truly understand for years, if ever.

He described some reasons why people don't like to write blogs and commented it:

I'm too busy.
I'm afraid to put my true thoughts on public record.
Nobody will read my blog.
Blogging is narcissistic.

I must say that Steve inspired me to write more. Just for fun.

Should I learn Lisp?

2011-01-12T02:05:00.003+02:00

I had been asking this question myself every time I had found something (blog post, article, book title, etc.) interesting related to Lisp. But those “ugly” brackets put me away again and again :-). So, what was happen and why I changed my vision?

I think I’ve got three triggers to change my mind: a) friends of mine works with Gensym/G2 platform and they are really inspired by Lisp power; b) I saw several Rich Hickey’s talks about Clojure and the last one c) Paul Graham essays.

Then, I started googling to find other opinions about Lisp (when I say “Lisp” I mean Common Lisp, Scheme, Clojure and other Lisp dialects).

Lisp Quotes
Bill Clementson wrote about this:

“Usually, rather than trying to convince people … I feel it is better to just spread the "seeds" and let people convince themselves. This is often better done with quotes and/or stories because these often highlight some salient feature that resonates better with people than arguments do.”

Also, check Paul Graham Quotes List.
I like this one:

"Lisp is worth learning for the profound enlightenment experience you will have when you finally get it; that experience will make you a better programmer for the rest of your days, even if you never actually use Lisp itself a lot." (Eric Raymond, "How to Become a Hacker")"

Lisp Dialects
Here is the lisp of the major Lisp dialect, as for me:

Common Lisp (CLOS)
Scheme
Clojure
Dylan
Arc
newLisp
Emacs Lisp

I'm sure this lisp uncompleted, but from my point of view other stuff is too specific.

Additionally you should check this page to get some syntax overview: Lisp: A side-by-side reference sheet

I think there are two major player, IMHO: Common Lisp and Clojure.
Common Lisp is just golden standard for all Lisps. Plus, all major Lisp related books were written for Common Lisp.

I would choose Clojure for practical reason. It just has JVM background and can use Java ecosystem. And it's the major features. The other good point is that Clojure is much simpler than Common Lisp.

Beginner Lisp Books
Common Lisp:


Practical Common Lisp, by Peter Seibel, 2005

Clojure:

Programming Clojure, by Stuart Halloway, 2009

Scheme:

Structure and Interpretation of Computer Programs, by Harold Abelson, Gerald Jay Sussman, Julie Sussman

People suggest to choose one "lisp" for start. I think Common Lisp must be in your learning roadmap, but it shouldn't be a start point.

Development Environment
I've analyzed a lot of opinions and made an obvious (and expected) conclusion. Whatever Lisp you want to use Emacs is the only one true way for the real Lisp development.
Emacs is very powerful and very complicated text editor. I have to invest a huge amount of your time to be really productive with it. But real lisper can't suggest your other editors.

Even for Clojure people suggest to use Emacs.
Don't forget that you'll get additional Lisp on your shelf with Emacs - Emacs Lisp (elisp). It uses for Emacs scripting and you must know it to tune Emacs properly.

Summary

I like Lisp after this small overview. This language has huge power and conceptual background which is different from what I've see so far. It's mean that Lisp can extent my conceptual horizon.
I should chose the only one Lisp for start. It's no simple task. I think that Clojure is better choice for me as for Java developer. But, Common Lisp has big legacy (books, community and history) which is very interested for me. In any case List is just for fun. I can't use it on my work :-(
I should invest noticeable amount of time for Emacs learning. And I don't like this.
Unfortunately, I can't learn Lisp this year. Because it will be fragmented learning process. And I have such approach. I like to dive into the subject and live with it. I have to set List as a goal for 2012 year.

Review: How To Become A Hacker?

2011-01-10T23:53:00.001+02:00

Recently I've read these philosophical essays: How To Become A Hacker, by Eric Steven Raymond and Teach Yourself Programming in Ten Years, by Peter Norvig.

It's worth reading. I think that it's like hacker "mantra" ;-) I don't want to retell all that stuff. Just want to sum up.

1. Programming language learning.
We should learn different programming languages from paradigm point of view: "classical" OOP languages (C++, C#, Java), procedural languages (C), functional languages (Lisp family languages: Common Lisp, Scheme, Clojure), dynamic and scripting languages (Perl, Python, Ruby) and web-related (JavaScript).

"Besides being the most important ... languages, they represent very different approaches to programming, and each will educate you in valuable ways."

It means that you should learn languages from different paradigms to get some conceptual knowledge.
E.g. You shouldn't learn Java and C#, or Python and Ruby. I think it's just waste of your time.

"To be a real hacker, you need to get to the point where you can learn a new language in days by relating what's in the manual to what you already know.This means you should learn several very different languages."

2. Learn Unix/Linux.
I think the best way to learn is to start playing with Ubuntu.

3. Learn English and native language.
You should be able the speak and write fluently in both.

4. Persistent learning
It's the key point to success in any profession.

Summary

"To follow the path:
look to the master,
follow the master,
walk with the master,
see through the master,
become the master."

How to set ${user} property in Eclipse?

2010-12-29T00:47:00.000+02:00

Select Preferences -> Java -> Code Style -> Code Template -> Section Comment -> Type
You can replace the author tag by whatever value you need and it will have an effect on new generated classes.

${user} uses the value of the user.name environment variable. You can check it via System.getProperty("user.name").

There are several solutions:

define it via command line:

C:/eclipse/eclipse.exe -vmargs -Duser.name="someUserName"

define it via eclipse.ini:

-showsplash
org.eclipse.platform
--launcher.XXMaxPermSize
256M
-vmargs
-Dosgi.requiredJavaVersion=1.5
-Duser.name="someUserName"
-Xms40m
-Xmx512m

My Bookshelf - Part Zero

2010-12-28T01:28:00.001+02:00

Each software developer spend some amount of time reading IT books. I have several reading directions and special sequence of reading. I think it would be interesting to share my virtual bookshelf: books which I've read and books which I'm going to read.

Here are books' categories:

Design, Patterns, Refactoring and Architecture
Agile Technique
Tools
Learning and Career Development
Java and JVM Languages
Other

I'm sure I will extend this list, but this one is OK as start point.

Maybe it will be good to group books by authors as well. Will see. Definitely, I have to try this approach as well.

In the next part I'm going to post about "Design, Patterns, Refactoring and Architecture" bookshelf.

Java Build Tools and Future

2010-12-15T01:00:00.001+02:00

It's always interesting to read comparison of Java build tools. There are two major player so far: Ant and Maven. But, I'd like to know more about other tools.

Here are some interesting links:

www.hjug.org/present/Java_Build_Tool_Comparison.ppt - short comparison matrix, it's really useful for overview
The future of Java build tools - conceptual review, worth reading, especially comments
http://java.dzone.com/news/maven-or-ant - pros and cons for both Maven and Ant
http://www.webforefront.com/archives/2009/09/java_build_tool.html - small Maven criticism
http://kent.spillner.org/blog/work/2009/11/14/java-build-tools.html - "Java Build Tools: Ant vs. Maven", I think it's really famous article in the Internet. Just read arguments of Maven hater.
http://community.jboss.org/wiki/Gradlewhy - Hibernate moved from Maven2 to Gradle!

Top 3 Java build tools:

I don’t want to mention the other tools. The list isn't small. I'm not sure if it worth spending time for learning/investigating new build tools. We should follow the trends.

Ant and Maven are good enough for any projects. But Gradle evolves really quickly. So, we can get additional "big" player on Java build tools field.

How to use Dropbox as SVN repository?

2010-12-10T00:13:00.002+02:00

You probably know about such cool stuff as Dropbox. So, I use it as on-line SVN repository for my own projects. It gives me an opportunity to have my own repository everywhere.
Check this post before go ahead: How to use Subversion & Dropbox to create an effective work management/backup system

So, 1) you have to create SVN repository in some Dropbox folder; 2) do the checkout from this folder on every work machine where you need to do something with your SVN repository. That's it.

Review: The Pomodoro Technique by Francesco Cirillo

2010-11-25T01:48:00.003+02:00

Some time ago I read this book "The Pomodoro Technique" by Francesco Cirillo
I have to say that it's really useful and super fast introduction for this particular time management technique. I highly recommend it for everybody interested in Pomodoro.
I don't want to analyze main chapters because you just have to read them all.
Of cause you read only about basic approaches and you have to adapt some of them. It's general practice. There is no single way to do the job, there is only recommended way to organize you work time. You have to start applying Pomodoro iteratively and make correction to "your" technique after each working day.

Have fun with Pomodoro.

Why Should I Attend Conferences?

2010-10-31T23:18:00.002+02:00

I'm mainly a Java developer. But, I always do some "diving" around new technologies, trends and just around other interesting stuff (read blogs, watch screencasts, etc.). And it's not enough for me. So, I've decided to attend some conferences. Here is the chronological list of conferences I've attended:

Ruby Bar Camp (September 26, 2009)
Ruby Shift (May 21, 2010)
Agile Base Camp (January 23, 2010)
Agile Base Camp (May 29, 2010)
PyCon Ukraine (October 23-24, 2010)

All these conference related to non-Java technologies. And what? The main benefit I've got is the real face-to-face communication with technology addicted people.
I've seen great, good and ugly presentations. This experience has opened my mind. Why?
Every conference which I've attended gave me the additional energy for the next attempts to learn something new, something great and interesting. Even if it's unpopular in my company and inside my local developer's community.
These conferences showed me the real people which stand behind the blog posts, forum posts, frameworks and libraries.
I'm a 100% sure that every developer must attend a conference just to feel the spirit of community.

Review: Pomodoro Technique Illustrated

2010-09-11T17:34:00.007+02:00

I've got a real pressure because I had to learn TOO many different things simultaneous. And I had very small time frame to do the job in time. I needed some tool which can help me to organize all my learning activities.
I remembered about Pomodoro. Without any delay I started reading this book: Pomodoro Technique Illustrated: Can You Focus - Really Focus - for 25 Minutes?, by Staffan Noteber

Chapter 1: One Activity at a Time
Pomodoro concepts overview. Author present simple examples which help us to understand the real value of this technique.

Chapter 2: Context
This chapter describes how our brain works. Basic ideas and simple worlds. It’s really pragmatic approach based on applicable examples and associations.

Chapter 3. Mechanics
This chapter help us to understand the Pomodoro process in action: Pomodoro sets, Activity, Iteration, breaks, Activity Inventory, Records.

Chapter 4. Interruptions
Clarifies the difference between the Internal and External interruption and gives several advices how to manage them.

Chapter 5. Estimate
Explains basic technique for Pomodoro estimation and estimate analysis.

Chapter 6. Adapt
This chapter shows some Pomodoro best practice: tools, length of Pomodoro, breaks, progress sheet, prioritizing, mind maps, reviews etc.

Chapter 7. Team
The last chapter, it gives some advices how to apply Pomodoro technique to pair work.

In general this book opened my mind. I'm going to try Pomodoro. The most beautiful thing it that this time management technique is very simple, has small set of rules and tools.

Summary: well written book, short and pragmatic. Good start point to learn Pomodoro technique and adapt it to your own needs.

(J)Ruby or Groovy for scripting in Java environment

2010-08-11T23:11:00.003+02:00

It's my dilemma. And I come to the conclusion that (J)Ruby is a better choice:

Groovy

Groovy provides easily integration with existence Java code-base.
Groovy is easy to learn for Java developers
Groovy has the similar "power" as (J)Ruby
Grails has "support" from SpringSource
Groovy/Grails has competitor inside SpringSource - Spring Roo.
Groovy has evolving community.

Ruby

JRuby can be integrated in existence Java code-base but no so good as Groovy
Ruby has amazing community (tutorial, screencasts, books, etc.)
Ruby language is "super sexy", but I think it's because of hype in community ;-)
Engine Yard is big player in Ruby community. It supports JRuby and Rubinius projects
Ruby can be run not only on JVM! So, I can reuse my Ruby-knowledge in different environments
Ruby is faster then Groovy.
Ruby has good support on *nix environments, but there are some issues with popular gems on Windows.

I know that all these ideas are subjective and you can select own pros/cons.

The another main item against Groovy is that there are so many JVM languages (Groovy, Jruby, Scala, Jyton, Clojure) and they are change each other in popularity from year to year. Groovy, Scala, Clojure are JVM based mainly (Clojure has CLR implementation). It's hard to get some expensive time to dive deeper in each of them.

Conclusion is pretty simple - use the right tool for the job.

Oracle UNDO DBF issues

2010-04-30T00:58:00.007+02:00

Oracle 10.2 is installed on Windows XP SP3.

Useful references:

1. Switch Undo Tablespace
2. Fun with UNDO tablespaces
3. ORA-01548: active rollback segment '_SYSSMU1$' found, terminate dropping tablespace
4. Oracle Init.Ora & SPFile
5. Automatic UNDO Management in Oracle9i

Problem description:
UNDO dbf file was f**ed up, it have to be removed and replaced.

Create temp tablespace and switch UNDO to it:

sqlplus> create undo tablespace UNDO_RBS1 datafile 'path_to_new_undo_dbf' size 500M AUTOEXTEND ON MAXSIZE 3900M;
sqlplus> alter system set undo_tablespace=UNDO_RBS1;

sqlplus> select status from v$rollstat;
STATUS
---------------
ONLINE
PENDING OFFLINE
PENDING OFFLINE
ONLINE
ONLINE
ONLINE
ONLINE
ONLINE
ONLINE
ONLINE
ONLINE

You can't drop or offline if status show offline pending.
Restart DB:

sqlplus> shutdown immediate;
sqlplus> startup;

And now try to drop undo tablespace:

sqlplus>alter tablespace UNDOTBS1 offline;
sqlplus>drop tablespace UNDOTBS1 including contents and datafiles;
*
ERROR at line 1:
ORA-01548: active rollback segment '_SYSSMU1$' found, terminate dropping
tablespace

Cause of The Problem
An attempt was made to drop a tablespace that contains active rollback segments.

Solution of The Problem
In order to get rid of this error you have to follow following steps.

1)Create pfile if you started with database with spfile.

sqlplus> create PFILE from SPFILE;

You can use the next command to get path to spfile (in my case pfile was located at "D:\oracle\product\10.2.0\admin\A7\pfile\init.ora.1252010112825" ):

sqlplus> show parameter spfile

2)Edit pfile and set undo management to manual.

undo_management = manual

3)Put the entries of the undo segments in the pfile by using the following statement in the pfile:
_CORRUPTED_ROLLBACK_SEGMENTS=(_SYSSMU1$,_SYSSMU2$,_SYSSMU3$,.....)

###########################################
# System Managed Undo and Rollback Segments
###########################################
undo_management=MANUAL
undo_tablespace=UNDOTBS1
_CORRUPTED_ROLLBACK_SEGMENTS=(_SYSSMU1$)

4)Mount the database using new pfile:

sqlplus> shutdown immediate;
sqlplus> startup mount pfile='fullpath to pfile'

5)Drop the undo segments,

sqlplus> drop rollback segment "_SYSSMU1$";

6) Drop Old undo tablespace.

sqlplus> drop tablespace UNDOTBS1 including contents and datafiles;

7) Add the new undo tablespace:

sqlplus> create undo tablespace UNDOTBS1 datafile 'path to new undo table space' size 500M AUTOEXTEND ON MAXSIZE 32000M;
sqlplus> alter system set undo_tablespace=UNDOTBS1;

8) Remove temp undo table space:

sqlplus> alter tablespace UNDO_RBS1 offline;
sqlplus> drop tablespace UNDO_RBS1 including contents and datafiles;
sqlplus> shutdown immediate;

9) Change the pfile parameters back to Undo_management = AUTO and modify the parameter Undo_tablespace=new_undo_tablespace_name and remove the _corrupted_rollback_segments parameter:

###########################################
# System Managed Undo and Rollback Segments
###########################################
undo_management=AUTO
undo_tablespace=UNDOTBS1
#_CORRUPTED_ROLLBACK_SEGMENTS=(_SYSSMU1$)

10) Startup the Database:

sqlplus> startup

NOTE: In step #3 I've tried to use _OFFLINE_ROLLBACK_SEGMENT = (_syssmu1$). But it didn't work.

How to change the default editor in Ubuntu?

2010-04-25T23:13:00.005+02:00

The default editor in Ubuntu is nano. But I like Vim.

$ sudo update-alternatives --config editor

And You will get the next:

There are 6 choices for the alternative editor (providing /usr/bin/editor).

  Selection    Path                    Priority   Status
------------------------------------------------------------
* 0            /bin/nano                40        auto mode
  1            /bin/ed                 -100       manual mode
  2            /bin/nano                40        manual mode
  3            /usr/bin/mcedit-debian   25        manual mode
  4            /usr/bin/vim.basic       30        manual mode
  5            /usr/bin/vim.nox         40        manual mode
  6            /usr/bin/vim.tiny        10        manual mode

Press enter to keep the current choice[*], or type selection number: 4
update-alternatives: using /usr/bin/vim.basic to provide /usr/bin/editor (editor) in manual mode.

Select 4, in this case and that's it.

How to use SUDO without password in Ubuntu?

2010-04-25T23:05:00.003+02:00

I don't need to type password all the time when I use sudo in Ubuntu.

$ sudo visudo

Type the next thing at the end of the opened file:

username ALL=(ALL) NOPASSWD: ALL

Save and close this file.

How to setup Ruby/Rails development environment, Part 2 - E-TextEditor

2010-04-22T00:30:00.005+02:00

There are tons of text editors which are good enough for Ruby/Rails/web development. And it's not so easier to choose the "best" editor.
I'd like to talk about my top three editors which like the most:

	Notepad++ It's the base text editor on my workstation. It has active community, plug-in repository developing fast enough. But, this editor doesn't have Rails syntax highlight, here I mean ERB files. So, for Rails editing I have to skip it (for now)
	Vim Cross-platform text editor. It has BIG, super active community with tons of plugins.
	E-TextEditor It's Textmate clone for Windows.

There are two choices for using these text editors:

Use Notepad++/E-TextEditor (or other editors) on host machine and connect to Ubuntu VM via tool such as ExpanDrive.
Use Vim via SSH (Putty) terminal. You'll have got plain linux terminal with all restrictions, but in this case you shouldn't install such tool as ExpanDrive which cost some money.

So, I will describe first solutions in this post and second - in the next post.

E-TextEditor and ExpanDrive
I assume that you install both e-texteditor and ExpanDrive.
Now, we can create some Rails project:

$ rails bar

And check IP address our Ubuntu VM:

$ ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0c:29:2b:58:78
          inet addr:192.168.72.132  Bcast:192.168.72.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe2b:5878/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:185 errors:0 dropped:0 overruns:0 frame:0
          TX packets:191 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:20339 (20.3 KB)  TX bytes:33193 (33.1 KB)
          Interrupt:18 Base address:0x2000

Now open ExpanDrive and setup connection to VM:

As you can see my Ubuntu VM disk is mapped to host machine and I can use it for my Rails development.
Now, we can use any Windows based text editor and made modification directly on Ubuntu VM disk:

For Rails scaffolding we use SSH/Putty terminal.

References:
How to setup Ruby/Rails development environment, Part 1 - Ubuntu VM

How to setup Ruby/Rails development environment, Part 1 - Ubuntu VM

2010-04-15T23:55:00.040+02:00

The most popular Ruby/Rails development platform isn't Windows. There are a lot of plug-ins, tutorials and blogs about Ruby/Rails on *nix like system. But, I'm Windows user (yes I know, Linux - rules!), so how can I use all community knowledge and easily apply it?
I've decided setup VMWare VM with Ubuntu Server v.9.10. And perform all Ruby/Rails development there via Putty (SSH).
I assume that You have installed Ubuntu VM.

This post is base on the next articles:

Step 1: Install Ubuntu VM - done
Step 2: Install Putty on Windows
Step 3: Configure Putty - Ubuntu VM connection
Check Ubuntu VM IP: ifconfig. Apply this VM IP in Putty setting. All next steps will be performed via Putty console
Step 4: Update Ubuntu installation

sudo apt-get update
sudo apt-get dist-upgrade

Step 5: Install all necessary libs

sudo apt-get install build-essential
sudo apt-get install ruby ri rdoc mysql-server libmysql-ruby ruby1.8-dev irb1.8 libdbd-mysql-perl libdbi-perl libmysql-ruby1.8 libmysqlclient15off libnet-daemon-perl libplrpc-perl libreadline-ruby1.8 libruby1.8 mysql-client-5.1 mysql-common mysql-server-5.1 rdoc1.8 ri1.8 ruby1.8 irb libopenssl-ruby libopenssl-ruby1.8 libhtml-template-perl mysql-server-core-5.1 libmysqlclient16 libreadline5 psmisc

Step 6: During installation MySQL will ask to setup credentials:

user = "root"
password = "root"

Check Ruby version

$ ruby -v
ruby 1.8.7 (2009-06-12 patchlevel 174) [i486-linux]

Step 7: Install RubyGems

wget http://production.cf.rubygems.org/rubygems/rubygems-1.3.6.tgz
tar xvzf rubygems-1.3.6.tgz
cd rubygems-1.3.6
sudo ruby setup.rb

sudo ln -s /usr/bin/gem1.8 /usr/bin/gem

Step 8: Install Rails

sudo gem install rails

Step 9: Install SQLlite

sudo apt-get install sqlite3 libsqlite3-dev
sudo gem install sqlite3-ruby

Step 10: Install MySQL client

sudo apt-get install libmysqlclient-dev
sudo gem install mysql

Step 11: Test your Rails instalation

$ rails myrailsapp

UI prototyping gets easier

2010-03-05T01:37:00.005+02:00

A wireframe or mockup screens always help us quickly define UI design direction. It helps team to concentrate on business and skip UI details for the next round.
It's not easy to choose some "good" tool for UI prototyping. There are a lot of freeware and payware solutions.
So, we've got dilemma.

I've choose the next directions:

free tool for easier prototyping UI stuff
or tool which can be used in other areas, so, knowledge accumulated with UI prototyping can be re-used.

Some time for googling and I've got:

10 Minute Mock Prototyping – Tips for PowerPoint very interesting post, worth reading.
PowerPoint Prototyping Toolkit (release 0.2)
Interactive Prototypes with PowerPoint tutorial for creation prototypes with interactions (mouse click, mouse over, etc.)

Plus, Pencil Project, you should take a look, opensource tool for making diagrams and GUI prototyping. It's pretty simple and get the thing done tool, IMHO.
If you choose to use PowerPoint, you should collect some UI components library for easier UI composing, etc. I've found several good examples.

Why I've chosen Ruby as main scripting language for my toolbox

2009-12-27T14:42:00.008+02:00

There are a lot of scripting languages: Perl, Python, Lua, Tcl, Ruby, JavaScript, Scala, Groovy, Erlang, Lisp, Scheme and Bash/Awk(as shell scripting).

There are criteria I've tried to match for my scripting language of choice:

Easy to learn
Active and big community
Amount of books and tutorials which are available
How many screencasts, conference videos are on-line?
Can replace shell scripting?
Number of text editors which support selected language
Code for fun? Is it suitable for selected language
Amount of useful frameworks and libraries

Let's discuss each of them.

JavaScript. I like this language, but it doesn't have standard serve-side API. There are a lot of implementation, but community have to work a lot to get valuable result. Check CommonJS to get more info

Perl. I've never tried to dig deeply into this and code style doesn't suitable for me. I can't code for fun. Number of tutorials/books are huge. Community is big. But, it's not my language of choice.

Lua. There are no killer features, as for me. In general language are cool and fast. Easy to learn.

Tcl. I just don't like Tcl language. It's main stopper for me. Community not so big in comparison with other languages. Amount the books is limited.

Lisp/Scheme. Great languages, but not for shell oriented scripting (It will be awkward to write shell scripts)

Erlang. Interesting language, but it's not general purpose. Good for concurrency domain. I have to skip it.

Scala/Groovy. Yet another scripting languages. I can see hype near these languages, especially Scala in Java community. I can predict, that the next year will have got another hype language(s).

Bash/Awk. I'd like to learn these two, but I'm windows user and I don't have a possibility to use these during my work. I can use Cygwin/MSYS, but it will be strange, awkward. It will be unnatural. I'm sure I need to get additional experience in Bash scripting, but not now. Time is my enemy.

Python vs Ruby. These two are very similar. Both have big and active community. Both are general purpose languages. Both are great.
But I falling in love with Ruby blocks. I love http://railscasts.com/. I'm not web-developer, but Rails concept is super-productive. I just love Ruby community.

But, there is one drawback. There is a ton of libraries and frameworks which are doing the same thing. Community super productive and it's in developing. There is no consistency. So, I have to be aware of any big changes in my favorite libraries/frameworks. I know it sounds strange but it's IMHO.

Shell scripting and task automation is one of the main direction to be productive. From time to time I have to work on different OS's (Windows, Linux, OS X) and environment. But my primary work station is Windows based. I'd like to have consistent scripting and automation tools for all these OS/environments. We can automate everything with Bash, etc. But what about Windows? So, choosing scripting language was good decision to create multi-platform toolbox. So, I can use my knowledge on any machine with minimal rework (if required).

Any developer should have some scripting language in his arsenal. The right tool for the job. Keep follow this idea and you will be productive.

*nix-like environments for Windows

2009-11-18T03:02:00.003+02:00

*nix like environment is good for developer and sysadmins, and really useful for end-user. That's why we've got KDE, Gnome and similar. But, I like it a lot even if I'm Windows user ;-). There are several cases to set up *nix environment on Windows:

setup Virtual Machine with some Linux distributive and you've got fully functional Linux. You can use VMware or VirtualBox.
or you can setup Linux-like environment in Windows (i.e. bash, gcc, make, grep, find, sed, etc.).

Here is "my" list of choice for such environments.

MinGW - Minimalist GNU for Windows. My top choice if you need GNU development programming tool set. Additional, if you need bash and similar tools install MSYS - general purpose command line environment.
Cygwin - is a Linux-like environment for Windows. It's very powerful if you need to develop OS-portable application on windows (it's provide substantial Linux API functionality).
GnuWin32 - provides ports of tools with a GNU or similar open source licenses. Check package list on their home page.
UWIN - it's the similar to MinGW and GnuWin32, but less popular.

I prefer to use MinGW/MSYS and Cygwin because they have great community support.

GNUstep Getting Started

2009-11-09T01:08:00.006+02:00

Objective-C popularity aggressively increased based on TIOBE Index (for October 2009)

The reason is simple -- iPhone and all related stuff. We should be ready to develop Objective-C based application in future. The worst thing I don't have a Mac, so I don't have development environment.
I need to get basic Objective-C knowledge, and here several solutions:

buy Mac
install Hackintosh on PC
try GNU compiler and play with Objective-C

The better choice is the last one (for me). As I'm a Windows XP user and I don't have a time to set up Linux, I'm going to use some Windows GNU GCC port: Cygwin or MinGW.
There are two cross-platform projects which implements Objective-C Cocoa/OpenStep APIs:

The Cocotron -- this project uses Mac machine for build (I didn't dig into this), but built application can be run on Windows.
GNUstep -- this project supports many platforms (Windows included).

My choice is

Here is the useful links for quick start:

www.gnustep.org -- official site
GNUstep programming mini tutorials -- the second place you should start with.
www.gnustep.it -- This site is dedicated to GNUstep. There are a lot of useful info.
GNUstep Application Project -- The purpose of this project is to implement a set of administrative applications and user level applications using GNUstep. Another aim of this project is to port as many applications from OPENSTEP/Cocoa to GNUstep as possible. Great place to look into real application.
Objective-C: Links, Resources, Stuff -- dig deeper in Objective-C culture
GNUstep Library -- additional info: Build Guides, User Documentation, Developer Documentation
GNUstep forum -- it covers the next categories: General, Help, Dev, Webmasters, Bugs, Announce, Apps
GNUstep HelpCenter -- links to various tutorials and articles on GNUstep.
GNUstepWiki -- just wiki

How to build your first GNUstep application in Windows?
In general it's simple, but if you have some troubles with it here is the links:

Installing and using GNUstep and Objective-C on Windows
Writing GNUstep Makefiles (I highly recommend it)
Compile Objective-C Programs Using gcc

The next post will be about tuning the development environment for GNUstep .

Syntax Highlighting Code in Blogger

2009-08-29T02:30:00.006+02:00

How to highlight code in Blogger? You can use SyntaxHighlighter.
I don't want to repeat other useful posts about adjusting Blogger for code syntax highlighter, so take look at these:

There is one useful feature in SyntaxHighlighter -- Bundled themes.

Here is small example:

public void printHello() {  
     System.out.println("Hello World");  
 }

Rails 2.3 migration issues with MySQL 5.1.3

2009-08-26T02:13:00.005+02:00

depot>rake db:migrate --trace
(in D:/Projects/RoR/depot)
** Invoke db:migrate (first_time)
** Invoke environment (first_time)
** Execute environment
** Execute db:migrate
rake aborted!
Mysql::Error: query: not connected: CREATE TABLE `schema_migrations` (`version`
varchar(255) NOT NULL) ENGINE=InnoDB
d:/tools/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.3/lib/active_record/connetion_adapters/abstract_adapter.rb:212:in `log'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.3/lib/active_record/connetion_adapters/mysql_adapter.rb:320:in `execute'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.3/lib/active_record/connetion_adapters/abstract/schema_statements.rb:114:in `create_table'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.3/lib/active_record/connetion_adapters/mysql_adapter.rb:473:in `create_table'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.3/lib/active_record/connetion_adapters/abstract/schema_statements.rb:320:in `initialize_schema_migration_table'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.3/lib/active_record/migraion.rb:436:in `initialize'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.3/lib/active_record/migraion.rb:400:in `new'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.3/lib/active_record/migraion.rb:400:in `up'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/activerecord-2.3.3/lib/active_record/migraion.rb:383:in `migrate'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rails-2.3.3/lib/tasks/databases.rake:116
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:636:in `call'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:636:in `execute'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:631:in `each'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:631:in `execute'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:597:in `invoke_with call_chain'
d:/tools/Ruby/lib/ruby/1.8/monitor.rb:242:in `synchronize'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:590:in `invoke_with call_chain'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:583:in `invoke'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2051:in `invoke_tas'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2029:in `top_level'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2029:in `each'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2029:in `top_level'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2068:in `standard_exception_handling'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2023:in `top_level'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2001:in `run'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2068:in `standard_exception_handling'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:1998:in `run'
d:/tools/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/bin/rake:31
d:/Tools/Ruby/bin/rake:19:in `load'
d:/Tools/Ruby/bin/rake:19

As I understood the client MySQL library doesn't work well with Rails 2.3. We can resolve this by using the older MySQL client library (libmySQL.dll). You can get it here http://instantrails.rubyforge.org/svn/trunk/InstantRails-win/InstantRails/mysql/bin/libmySQL.dll.
Just put it in <ruby base dir>\bin\ and restart MySQL service.

Top Ruby screencast resources

2009-06-03T00:32:00.006+02:00

As you know there are several way to kick-off and learn a new programming language, environment or special tools:

tutorial
screencast

But, now screencast is more popular for effective start and feature demonstration. So, I'm trying to collect as more as possible screencast resources for learning Ruby and Rails.

http://railscasts.com, it's the most popular free Rails screencasts
http://sdruby.com, it's San Diego's Ruby community, there are about 59 Ruby and Rails screencasts
http://www.rubyplus.org/episodes, Free Ruby and Rails Screencast, about 93 episodes
http://www.tekniqal.com, there are 17 tutorials covering basic Ruby topics
http://www.confreaks.com/events, here is located videos from several Ruby conferences
http://showmedo.com/videotutorials/ruby and http://showmedo.com/videotutorials/rubyonrails, it's great resource for learning from ground up. There are a lot of interesting videos for beginners. Also, this resource includes other areas, not only Ruby/Rails related
http://www.bestechvideos.com/tag/ruby-on-rails and http://www.bestechvideos.com/category/development/ruby, video collection from different conferences, presentations, etc.
http://railslab.newrelic.com/scaling-rails there are educational videos, teaching you just about everything you need to know to create a Rails application that can scale
http://rubytu.be is a community driven collection of Ruby related videos and screencasts
http://www.learnivore.com is another great screencast aggregator
http://www.teachmetocode.com/screencasts is similar to railscast.com but have less posts, it's worth to look into

Effective way to be an Expert

2009-03-16T21:35:00.001+02:00

I've found great post about How to Become an Expert. The Effective Way.
The core idea is:

Experts are made, not born. Experts are made by themselves. It is a long, thorny and hard road. But this road makes their life interesting, positive, meaningful and brings happiness from achieving a rare gift - mastery in the field they love.

I invite you to read that post. Enjoy