Senthil Balakrishnan

Cross-Platform Mobile development tools/frameworks

noreply@blogger.com (Senthil Balakrishnan) — Sun, 20 Nov 2011 16:56:00 +0000

Was exploring some cross-platform mobile frameworks in the market. Even though there are lot of them in the market. Couple of open source solutions sounded very impressive.
1. Rhomobile
2. PhoneGap

Tried some samples on Rhomobile, yet to try phone gap. In a way these frameworks saves lot of time & cost involved in developing application specific to an operating systems / app markets. Instead of working on a specific SDK's it's a no-brainer to choose such frameworks. Write once & port to any device type. How cool it is !!!, way to go...

web-log-analyzer - Hosted a project in google code base today

noreply@blogger.com (Senthil Balakrishnan) — Sun, 31 Jul 2011 03:47:00 +0000

Hosted a project in google code base today "web-log-analyzer". Simple Utility to analyze your web access log to help you identify potential traffic, response times (min/max/avg), most used URL's etc.

http://code.google.com/p/web-log-analyzer/

Garbage Cat - Analysis of you GC Log

noreply@blogger.com (Senthil Balakrishnan) — Sun, 31 Jul 2011 01:05:00 +0000

Came across this handy utility(garbagecat) to analyze Garbage Collector logs. Simple to use, output contains nice analysis report & recommendation on your GC.

Refer the documentation for more details on the usage.

My Test Drive on JBoss AS 6.0.0

noreply@blogger.com (Senthil Balakrishnan) — Sun, 12 Jun 2011 00:27:00 +0000

Took a test drive of JBoss 6.0.0 this weekend, thought would be nice to summarize my observation (with the background of using JBoss 4.3.0 version for my current projects).

JBoss 6.x.x is a re-architecture of JBoss 4.x with new the kernal (JBoss Microcontainer). Good news for application developers not much of change to the folder structure with exception of few new configuration files & some old ones were moved around.

High Lights

Default support to Java EE 6.0 Specification support.
JSF 2.0 support with integration with Bean Validation (JSR-303)
CDI (Contexts and Dependency Injection) JSR - 299 , Weld is JBoss project to support CDI.
Hornet MQ is the default & recommended messaging infrastructure.
New Apache CXF-based JBossWS stack.
JBoss Embedded AS
New Admin-Console to ease the server administration.

Admin-Console

New Admin-Console is a refresher, user friendly with tree based navigatio.
Lot of resembles to Weblogic Admin console :), never mind it does the purpose.
All configuration parameters are persisted for good, unlike the JBoss 4.* version.
"Service Binding Manager" Component externalizes all port configuration for a given/running profile. This saves lot of time fiddling with the raw .xml files :) as in 4.3.0.
Applications (.war, .ear) can be added/updated dynamically using the console.
Queues & Topic can be added dynamically using the console.
Database connection pools can be added dynamically using the console.
You have provision to restart/start/shutdown the server using the admin console.
Very detailed Garbage Collector / Memory pool info on the console.
The Metric tab for every component provides you useful statistics/metrics an the component. Ex: Selecting a queue provides (Message count, consumer count etc.)

JMX-CONSOLE

JMX-CONSOLE is still available, but with a new look & feel.

Others

Jboss VFS (Virtual File System), help yourself reading this article to understand.
Jboss Web is the default webserver offering from JBoss 5.x.x, build on top of Tomcat.
Felt the Server startup & Shutdown is slower than 4.3.0 GA :( hoping minor tweaks should take care of it.
Couldn't find any documentation on migration from 4.3.0 to 6.0.0, will keep looking...

Reference
Jason Greene - What's new in JBoss AS 6.0.0
Admin Console user guide
www.jboss.org
www.java.dzone.com

Power of AccessLog & Tomcat Valve configuration

noreply@blogger.com (Senthil Balakrishnan) — Fri, 10 Jun 2011 01:09:00 +0000

In recent past we faced quite a performance issues resulting in different modes of collecting performance statistics from web server. One of the handy tool was web server access logs, all I had to do is configure my webserver to write access logs. It dumps all the requested information (URL, Timestamp & Even roundtrip/response time of a request), How cool... with zero additional code you get response time of each request.

Link below details of access log configuration on tomcat, this could vary depending on the type of webserver used. But every webserver would have a access log by default.
http://tomcat.apache.org/tomcat-5.5-doc/config/valve.html#Access_Log_Valve

All different types of valves supported by Tomcat, most useful of it all is "Request Dumper" valve (dumps all request detail) & "Access Log" Valve.
http://tomcat.apache.org/tomcat-5.5-doc/config/valve.html#Request_Dumper_Valve

Example, below configuration (%D %T) will log response time for a request & timestamp of the request.

Valve className="org.apache.catalina.valves.AccessLogValve" prefix="localhost_access_log." suffix=".txt" pattern="%D %T"

Lot of tools can help you analyze the access logs & provide more insight of the usage response time etc.

http://www.nltechno.com/awstats/awstats.pl?config=destailleur.fr

Conclusion: We all know it's mandatory for a web server to have an access log,
but the good part is this can greatly ease performance study & tune
your web application.

How to use Intent to pass object ?

noreply@blogger.com (Senthil Balakrishnan) — Mon, 27 Dec 2010 02:55:00 +0000

During my eZeditor app development I figured out how to pass an object using intent from one activity to another.

Example:

If you want to pass an Object (Note.java) from one activity to another.
The Note.java should implement android.os.Parcelable interface.
Before you say startActivity(intent) on the source activity to navigate.
Say intent.putExtra("com.ez.editor.note", note); where note is an object.
On the target activity this.getIntent().getParcelableExtra("com.ez.editor.note"); should return you the object that you intent to pass.

public class Note implements Parcelable {

public static final Parcelable.Creator CREATOR = new Parcelable.Creator() {

public Note createFromParcel(Parcel in) {
return new Note(in);
}

@Override
public void writeToParcel(Parcel out, int flags) {
out.writeString(name);
out.writeInt(index);
}

public Note[] newArray(int size) {
return new Note[size];
}

};
}

Android eZedit (My first open App)

noreply@blogger.com (Senthil Balakrishnan) — Mon, 27 Dec 2010 01:35:00 +0000

Application Name: eZedit (Android Application).

API Used: SQLLite Database, Custom View (onDraw), Usage of intent, Touch/Click Listeners & etc.

Objective: Simple android app let's you "Write your notes in your own handwriting" by touching the screen.

Android Eclipse project: eZedit.zip

Android installable: eZedit.apk

Android Version: Android Platform 2.2 / API level 8

Disclaimer:

I have tested it on an emulator, never on a real phone.
No warranty & support will be provided.
The code is open for reuse.
Try at your own risk :)

Is there a way to surprise your loved ones after "Death" ?

noreply@blogger.com (Senthil Balakrishnan) — Wed, 21 Jul 2010 02:53:00 +0000

Even writing "Death" makes me sad & terrified, but sometimes things change very little even if you want to. Every one of us has an end to this life, but our love for people around doesn't change much. If you have seen the movie "P.S. I love you", I felt amazed that someone can plan so much after his death to surprise and gift his wife at perfect instances. That's exactly what i am talkin about.

Is it possible or any entrepreneur out their thinking about such a service, were someone can subscribe and pay for a service that need to be performed after his/her death :). Typically, Schedule all the moments and time to gift and surprise his/her loved ones.

I know I sound crazy here, not all that shown in movies can be brought to reality, but if it really makes someone special to you happy, Why not ?

Stuff that Interest me - 07/15

noreply@blogger.com (Senthil Balakrishnan) — Fri, 16 Jul 2010 01:33:00 +0000

Just started this section, will get this organized and interesting soon...

Interesting Projects:

Interesting Post:

8 Traits of a Great Leader

noreply@blogger.com (Senthil Balakrishnan) — Sun, 11 Jul 2010 14:34:00 +0000

One question keeps popping up all the time "What makes a true leader ?". In all my years of experience, i have seen many leaders whom i really admire, worship & imitate (to be frank). I am very sure everyone of us would have such icon, and their influence on each one of our work hence this is "My Version or Belief of a Great leader".

Style Of Leadership: There is no one single recipe to be a great leader, first trait is to be yourself and have a style of your own. Effectiveness of a leadership is directly proportional to the context (environment, industry, nature of work & type of people you handle).
Courage: You step back, your team does the same. As a leader you need to be man enough to speak when you have to. (customer, top management doesn't matter).
Talk less: Show "How to get things done?", rather than lecturing for hours.
Understanding individuals: Every human being is unique and they get motivated for some, and may not for some. You need to understand, better than being a clown.
Panic - Band Wagon: Don't jump in to the panic band wagon when the whole team is already in their. These are times of fight back and thinking rationale and no time for panic.
Innovation: Just like how one goal can bring the spirit back into the team. It's important to keep innovating, this means a lot of positive energy, openness to compete.
Be a real captain: You should be the last person to jump from a wrecking ship, Believe me this means a lot of guts.
Winning Habit: Everybody wants to be on a winning team, winning is a critical factor for further success as a leader. All you can do here is to give yourself a best chance, leave the rest to the fate...

Guava or Google Collection library

noreply@blogger.com (Senthil Balakrishnan) — Sun, 20 Jun 2010 02:30:00 +0000

Guava or Google Collection library - just started to play with it. One thing attracted me the most is MapMarker which resembles the behavior of ConcurrentMap with eviction timeouts and choice of soft, weak references. Objective of the project says "Productivity aids to Java Programmers", Still exploring to see how it's useful in real context...

Loads of Material In reference to Guava,
http://jnb.ociweb.com/jnb/jnbApr2010.html
http://scaramoche.blogspot.com/2010/05/googles-guava-library-tutorial-part-1.html
http://code.google.com/p/guava-libraries/

Unit Tests - "Written Once and Forgotten Forever"

noreply@blogger.com (Senthil Balakrishnan) — Sat, 19 Jun 2010 14:55:00 +0000

I have come across many unit test cases that are written once and forgotten for ever, with all the dataset/environmental dependencies in it. What is the importance of dataset/environment? Let's take an example, observe the test case below.

public void testEmpFinder () {
//Weird Test case for Fun!!!
String result = "JOHN";

//Passing employee id returns employee object.

//verify the name matches.

Employee emp = EmpFinder.find(1);

assertEquals(emp.getName,result);

}

What's wrong? The developer had made an assumption, that on querying with employeeid='1' will return employee with the name "JOHN". The data could be coming from a database table "EMPLOYEE". But It’s very evident this test case would fail if run on an environment where the employeeid='1' data doesn't exists. This makes the test cases obsolete the moment they are written.

Approach

1. Save Insert/Delete datascript, that could be run on test setup () and delete test data on completion of test.

2. You could use something like DBUnit (http://www.dbunit.org/) which exports and imports the database data into an XML dataset. - Not sure of DBUnit support for modern day ORM's (Hibernate).

Conclusion:

Unit tests should match & sustain life time of source, after all its a guarantee card to your source code. We just looked at database dependency for example, how about dependencies such as JMS, Content Repository, LDAP etc. Writing a test case with all its data & environmental dependencies Mocked & externalized is an Art.

Chekout In Dzone

VisualVM - Simple Profiler

noreply@blogger.com (Senthil Balakrishnan) — Wed, 16 Jun 2010 01:42:00 +0000

VisualVM is a handy tool just like the JConsole, with additional features of a commercial profilers. You could profile your application by CPU & Heap utilization (by class/method). You can even profile a server remotely, check out for documentation.

It's a must to have tool for java developers...

Reference:
https://visualvm.dev.java.net/features.html
http://blip.tv/file/1582849

Is flexibility enemy of standardization ?

noreply@blogger.com (Senthil Balakrishnan) — Tue, 15 Jun 2010 00:45:00 +0000

I was thinking about evolution of java & open source world. What comes to my mind is the flexibility it offers to build your own stack of tools & technology when you start a project, cool!!! isn't it. You could explore, develop, cutting edge, unknown, unnamed open source project in your project....

But software is not about using cool technology all the time, isn't it ?

What about skill set to manage and maintain it ?
What about support for the technology and open source used ?
What about wear and tear of changes happens over the life cycle ?

I tend to feel too much of flexibility leads to problems, which are unnoticed during the architecture and development of the project and get's uncovered during maintenance phase. Same application developed in .net takes lesser effort than java, what do you think is the reason ? Why every java projects are different by technology rather than business ? Is this the price to pay, to use an open platform independent languages & specifications ?

Architects come up with cool stuff, believe me it's the least used feature in the actual project. To sum it up, flexibility to choose the specification, implementation, technology, open source, commercial blah blah!!! leads to problems in later stages of the project, which very few people have stayed long enough to see them. It's also important to consider other aspects like skill set, proven architecture, standardization, support and etc in a software architecture than just being cool......

After all this is my blog, and i am bored of being cool :) ...

How to post XML code on Blogger

noreply@blogger.com (Senthil Balakrishnan) — Thu, 10 Jun 2010 23:20:00 +0000

Paste your XML content here and click on encode. Copy the encoded content and paste in your blog. It safes lot of your time encoding it yourself....

This method is not applicable inside the application server. See the J2EE spec, e.g. J2EE1.4 Section 6.6

noreply@blogger.com (Senthil Balakrishnan) — Thu, 10 Jun 2010 23:09:00 +0000

javax.jms.IllegalStateException: This method is not applicable inside the application server. See the J2EE spec, e.g. J2EE1.4 Section 6.6
2010-06-10 16:18:51,656 503469 ERROR [STDERR] @main at org.jboss.resource.adapter.jms.JmsSession.checkStrict
(JmsSession.java:754)
2010-06-10 16:18:51,656 503469 ERROR [STDERR] @main at org.jboss.resource.adapter.jms.JmsMessageConsumer
.setMessageListener(JmsMessageConsumer.java:174)

Fix:
Adding the following in the file, default/deploy/jms-ds.xml (or) production/deploy/hajndi-jms-ds.xml based on the profile used, fixed it.

<config-property name="Strict" type="java.lang.Boolean">false</config-property> under "<tx-connection-factory><jndi-name>JmsXA</jndi-name>"

Opensource entry into Cloud space :)

noreply@blogger.com (Senthil Balakrishnan) — Thu, 10 Jun 2010 12:10:00 +0000

Read this article at Dzone yesterday, sounded very interesting. As a matter of fact, it's an opensource project that could give you all that GAE or EC2 can provide with all opensource stack.

The beauty is, you can have your own cloud built with in your firewall and have your apps follow GAE API to be portable, how cool it is :) checkout - Typhoonae

MongoDB

noreply@blogger.com (Senthil Balakrishnan) — Wed, 02 Jun 2010 03:02:00 +0000

MongoDB bridges the gap between key-value stores (which are fast and highly scalable) and traditional RDBMS systems (which provide rich queries and deep functionality).

I strongly feel the cloud players should adopt this approach, since so much of knowledge, best practices and standardization has gone into the design of traditional RDBMS Systems. I strongly feel ditching them is not the best way to go....

I haven't tried Mongo myself yet, would do soon....

Reference:
http://www.mongodb.org/

EasyMock your Jms Listener

noreply@blogger.com (Senthil Balakrishnan) — Fri, 28 May 2010 01:03:00 +0000

EasyMock as the name states "Its an easy to Mock framework" that mocks interfaces to do better unit testing. I tried some samples and found it really amazing, and thought of creating a sample that helps to understand mocking better.

Assume JMSListener is a business class that listens to a JMS Queue and does some business processing based on the received message. The problem with such components are they are dependent on some resources external (J2ee Container, Queue, database, LDAP etc.) to the code itself. This makes unit testing difficult and puts the EasyMock on driving seat :).

package com.jms;

import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageListener;
import javax.jms.TextMessage;

public class JMSListener implements MessageListener{
public void onMessage(Message arg0) {
TextMessage msg = (TextMessage)arg0;
try {
//Some Mission Critical Logic :)
System.out.println("Got the message.. \n"+msg.getText());
} catch (JMSException e) {
e.printStackTrace();
}
}
}

Let's see the Unit Test and how EasyMock Mocks the Message interface, The highlighted lines shows the Magic of EasyMock & power of interfaces...

package com.jms;

import static org.easymock.EasyMock.*;
import javax.jms.JMSException;
import javax.jms.TextMessage;
import junit.framework.TestCase;

public class JMSListenerTest extends TestCase {
private TextMessage mock;
private JMSListener listener;

protected void setUp() {
mock = createMock(TextMessage.class);
listener = new JMSListener();
}

public void testRemoveNonExistingDocument() throws JMSException {
expect(mock.getText()).andReturn("content");
replay(mock);
listener.onMessage(mock);
verify(mock);
}
}

Reference
http://easymock.org/EasyMock2_2_Documentation.html

JavaAssist - Byte Code Enhancement simplified

noreply@blogger.com (Senthil Balakrishnan) — Wed, 26 May 2010 22:26:00 +0000

JavaAssist - Byte Code Enhancement simplified.

JavaAssist is a class library to manipulate your Java Byte Code without touching the source. Let's take an example of measuring
time taken to execute a method.

public class Subject {

/**
* Timetaken for start & end of the method
* @throws InterruptedException
*/
public void method2() throws InterruptedException {
//Some business logic :)
Thread.sleep(2000);
}

}

To measure time taken for executing subject.method2(), you could enhance the Subject.methods() by adding code start and end of the method as shown.

public class JavaAssist {
public static void main(String[] args) {
public static void timeTaken() {
try {
ClassPool p = ClassPool.getDefault();
CtClass cc = p.get("Subject");
CtMethod meth2 = cc.getDeclaredMethod("method2");
meth2.insertBefore("System.out.println(\" Start : \"+new java.util.Date());");
meth2.insertAfter("System.out.println(\" End : \"+new java.util.Date());");
//cc.writeFile(".");
Class c = cc.toClass();
Subject s = (Subject) c.newInstance();
s.method2();
cc.detach();
} catch (Exception e) {
// suppressed
}
}
}
}

Output:
Start : Wed May 26 17:24:18 EDT 2010
End : Wed May 26 17:24:20 EDT 2010

Cool isn't it!!!. It can do wonders check the API section for more details.

Reference
http://www.csg.is.titech.ac.jp/~chiba/javassist/tutorial/tutorial.html#read
http://www.csg.is.titech.ac.jp/~chiba/javassist/html/

Unit Test - "Written once and forgotten for ever"

noreply@blogger.com (Senthil Balakrishnan) — Tue, 25 May 2010 22:50:00 +0000

I have come across many Unit test cases that are written once and forgotten for ever, with all the dataset/environmental dependencies in it. What is the importance of dataset/environment? Let's take an example, observe the test case below.

public void testEmpFinder () {

//Weird Test case for Fun!!!

String result = "JOHN";

//Passing employee id returns employee object.

//verify the name matches.

Employee emp = EmpFinder.find(1);

assertEquals(emp.getName,result);

}

What's wrong? The developer had made an assumption, that on querying with employeeid='1' will return employee with the name "JOHN". The data could be coming from a database table "EMPLOYEE". But It’s very evident this test case would fail if run on an environment where the employeeid='1' data doesn't exists. This makes the test cases obsolete the moment they are written.

Approach,

1. Insert/Delete data script that could run on test suit setup () and delete test data on completion of test.

2. You could use something like DBUnit (http://www.dbunit.org/) which exports and imports the database data into an XML dataset. - Not sure of DBUnit support for modern day ORM's (Hibernate).

Conclusion:

Unit test should match & sustain life time of source, after all its a guarantee card to your source code. We just looked at database dependency for example, how about dependencies such as JMS, Content Repository, LDAP etc. Writing a test case with all its data & environmental dependencies externalized is an Art.

Memory Profiling Java Application

noreply@blogger.com (Senthil Balakrishnan) — Tue, 04 May 2010 00:19:00 +0000

In continuation to the last post on Jboss Profiler, thought of sharing this simple and elegant memory profiler that ships with your JSDK (jmap)...

To know the # of instances & type of objects in the heap in a simple and quick way,

jmap -histo > snapshot1.txt
Sample Output:

num #instances #bytes class name
--------------------------------------
1: 5555 6013016 java.util.Hashmap
2: 103 482888 org.apache....
3: 2000 334928 org.jboss...
4: 1280 274976 org.spring...

To troubleshoot a memory leak, do the above command multiple time and observe the snapshot.
jconsole is good enough, but this give a verbose details on the memory.
jhat is cool utility to browse the object topology over http on a specific port for analysis.

Memory Intensive Operation In Java

noreply@blogger.com (Senthil Balakrishnan) — Sat, 01 May 2010 13:24:00 +0000

Memory intensive processing without bloating Java Heap ????

Not many must be aware of the package java.lang.ref.*, and their impact on Garbage Collectors,

Strong Reference (Frequently used)
Soft Reference
Weak Reference

A sample to demonstrate the references here, this program will fail with OutOfMemory without a weak reference (as we all know). With weak reference you can see the program runs for ever.

But the downside is the GC will treat these references low in priority and does cleans it up from the heap, you are bound to see Null Pointer Exceptions. Another alternate is SoftReferences which could fit in very well in most of the business cases and keep your memory foot print clean.

public class WeakRef {
public static WeakReference lst = new WeakReference(new ArrayList());
public static void main(String[] args) {
while (true) {
try {
lst.get().add("EEEEEEEEEEEEEEEEEEEEEEEEEEEEE");
} catch (Exception e) {
e.printStackTrace();
}
}
}
}

Leaving this article a WeakReference to StrongReferences below,

Jboss Profiler 2.0 - Coo!!!

noreply@blogger.com (Senthil Balakrishnan) — Sat, 01 May 2010 00:56:00 +0000

Got myself into a tough situation of Memory profiling a web application. I had a custom written profiler which does cool on measuring the time consumption, but not the memory. Since most of the profilers are commercial, tried my hands on "JBoss Profiler 2.0", Wow!!! never seen a profiler work in just 3-4 steps :), don't believe me try it yourself,

Steps:
1.Download "JBoss Profiler 2.0" - http://labs.jboss.com/jbossprofiler/downloads.html
2.Copy files to your Jboss,

jboss-profiler.jar -> jboss/bin
jboss-profiler.properties (Add packages to be instrumented in includes) -> jboss/bin
javassist.jar -> Jboss/bin
jboss-profiler.sar -> jbossas/server/(default)/deploy

3.Add the following to your run.conf or run.bat JAVA_OPTS,
-javaagent:jboss-profiler.jar -Djboss-profiler.properties=jboss-profiler.properties

4.Start the Server, Use the Client program to collect the statistics,
java -Xmx512m -Djboss-profiler-client.properties=jboss-profiler-client.properties -jar jboss-profiler-client.jar -h(server-host) -P(server-port) snapshot

Reference:
1.Excellent User Guide comes with the download, it has everything you needed to know.

Checkout In Dzone

Personal Tweet Robot - Approach

noreply@blogger.com (Senthil Balakrishnan) — Sat, 10 Apr 2010 18:06:00 +0000

Personal/Personality based Tweet Robot ?

Proxy based utility that captures and analyzes user's internet behaviors (such as websites, keyword etc.).
Using the collected information, the robot should be able to generate automatic tweets using the twitter credentials and twitter API's.
Robot can also search the internet based on user's behavioral understanding and generate automatic updates reflecting the true personality of the user.

Still an approach in my mind, still thinking on the details.