Balaji Natarajan

SCEA Preparation: Day 2

Balaji Natarajan — Tue, 13 Jan 2009 17:09:20 +0000

Design patterns and Installing glassfish server

Design Patterns
They say “Learning technology” and “Learning to design with technology” are different and if you have to accomplish the later you must know design patterns. In the context of present day’s framework era, like Spring, JBoss Seam, plumbing codes have been taken out virtually from the developers. Also the pioneers of these frameworks built it with excellent orchestration of design patterns. So if you know various aspects of Spring/Seam, do you ever need to learn Design Patterns? Why whould you have to learn MVC (Definitely you are not going to write Servlets and JSPs) when there is Spring MVC/Sun-Seam JSF available out there?
Design patterns are the key to understand any frameworks. Even if a new framework incarnates in the market, knowing the design patterns and its application, your learning curve is very very less.
Design Patterns are the ARCHITECT’s LANGUAGE. Hope i would have convinced a bit about design patterns.

Coming back to our SCEA thingy, Design Patterns are at first priority in my SCEA preparation. Following are the 2 excellent books, the first one being indispensable and cannot be missed out.

Design Patterns: Elements of Reusable Object-Oriented Software by Erich Gamma, Richard Helm, Ralph Johnson, John M. Vlissides
Core J2EE Patterns: Best Practices and Design Strategies (2nd Edition) by Deepak Alur, Dan Malks, and John Crupi

I have backed these books from library and started reading it. First book is not language specific (examples given in C++), whereas the second entirely deals with J2EE patterns (most of these patterns (mainly relating to EJB) are now irrelevant, you can skip them safely). I have started reading the first book, finished with Composite View pattern and parallely referring the 2nd book for J2EE (now Java EE) specific things. Following few blogs will be more about design patterns & UML and less about EJB & Webservices as learning the former influences a lot in learning the later.

Online Resource: (If you dont have enough enthusiasm to read a whole book on design patterns)
1. http://www.fluffycat.com/Java-Design-Patterns/ (Code examples are very useful to learn)

Video tutorial:
http://sourcemaking.com/design-patterns-vidtut?a=5527

Installing glassfish server
Practice, Practice and Practice. Repeat this word 1000 times here. We need an application server for practice. Tomcat will do (as an application server) with present advancements in persistence area. Yet we need a traditional application server. Glassfish is what i would suggest. If you love tomcat, you will love Glassfish too. I use Linux (Ubuntu) at home and installed Glassfish without any hassles. Installed it today in Windows after tackling few problems and ran it. Will include the installation steps (both Linux and Windows) here asap.

EOD 2, I am all set to learn Design patterns (finished Composite View pattern) and my Glassfish server is ready to run my examples.

SCEA Preparation: Day 1

Balaji Natarajan — Tue, 13 Jan 2009 17:05:56 +0000

The wait is over. Two and a half years over and now i am all set to prepare for Sun Certified Enterprise Architect (SCEA 5.0). They say, that we need at least 5 years of experience (not mandatory) to get SCEA certified. What i believe is, in the course of preparation, we will learn and accomplish a lot. I will update this blog honestly with consistency about my preparation. Following are the very high level information about SCEA and what i am now heading to.
SCEA: (Brief Story, will get updated) It certifies you as a better architect. It identifies you as a architect than a programmer. It expects you as a person who can develop a solution to a problem and deliver that as a model which should be implemented by others. It is claimed as the Pinnacle of Sun certifications. Following are the important areas it covers

1. Design Patterns
2. Model Driven Architecture (MDA) and UML 2.0
3. EJB
4. Webservices
5. Security

My very brief preparation agenda
Currently i have accomplished SCJP and SCWCD. Now i am preparing for SCBCD (Sun Certified Business Component Developer for Java EE 1.5) and SCDJWS (Sun Certified Developer for Java WebServices) simultaneously. Well, these two preparations are absolutely helpful for your SCEA. You can ask me, why we need to do SCBCD and SCDJWS when we can directly take SCEA. Remember, SCEA identifies you as an architect whereas SCBCD and SCDJWS identifies you as a programmer. Following a certification ladder like this SCJP -> SCWCD -> SCBCD -> SCDJWS -> SCEA is always good.

Installing Glassfish on Ubuntu Linux

Balaji Natarajan — Mon, 12 Jan 2009 19:17:29 +0000

Successfully installed Glassfish server on Ubuntu 8.04 for my certification preparation. What haunts is that the 256 MB Laptop cannot uphold the heavy/lite glassfish server. I am thinking to install a more light weight Linux, may be xubuntu for running glassfish server and deploy example apps.

Following is the ultra-quick list of commands that will take you in no time installing Glassfish on Ubuntu 8.04 (Hardy Heron) Linux. Those in bold letters are the commands. Open a terminal and execute these in sequence.

java -version // Check java version. It must be either Java 1.5 or Java 1.6. If not install Java by typing sudo apt-get install sun-java6-jdk. It asks your password, after you enter it, it will install Java 6.
wget http://java.net/download/javaee5/v2ur2/promoted/Linux/glassfish-installer-v2ur2-b04-linux.jar // get the link of latest glassfish server jar for linux from https://glassfish.dev.java.net/public/downloadsindex.html
java -Xmx256m -jar glassfish-installer-v2ur2-b04-linux.jar // Click Accept in the license window that opens
cd glassfish
sudo chmod -R +x lib/ant/bin // Enter password
lib/ant/bin/ant -f setup.xml //Run ant script
cd bin //Go to the directory (usually bin) where asadmin command is available. You can find this by simple ls command or through GUI file xplorer
./asadmin //Run asadmin
asadmin> start-database
asadmin> start-domain domain1
Type http://localhost:4848/ in browser and login as username: admin and password: adminadmin
asadmin> exit // To shutdown the server, type this in the terminal window

Following is the screenshot of Glassfish server admin console. It comes with default derby database and very much intuitive. This will be of great aid to practice our EJB and Webservice examples and i am going to use it to the maximum to leverage maximum.

Registered Linux User #482988

Balaji Natarajan — Sun, 11 Jan 2009 13:44:49 +0000

Registered myself as a linux user in http://counter.li.org/
Registered my machine too.
And here is the logo

Beginning JBOSS Seam

Balaji Natarajan — Fri, 02 Jan 2009 19:36:57 +0000

Just got a copy of

from my friend Dinakaran to spend my time over the weekend after i promised my Project Manager to develop an Enterprise Framework using Seam within January end. Turned few pages in train while returning to home and the Introduction by Joseph Nusairat is very easy to start with the concept. Finished first chapter and really surprised by the “Hello World” example using JSF and Seam (with just a @annotated Java Bean and a JSF JSP – thats it). Hope it will go well and i need to complete this book over the next week to start with my end-end healthcare Enterprise Framework. So i just got this book because it is the only one available on the topic “Seam” in our library. What Seam books you read? and What would you prefer?

Wish you a Happy New Year 2009!

Balaji Natarajan — Thu, 01 Jan 2009 03:46:16 +0000

I wish everyone in this world a very Happy New Year 2009!
Let this year 2009 brings happiness, joy and peace.
Let the God bless our planet earth with all enriching nature and peace!
My resolutions are many for this year but not limited to

To complete SCEA and help more people on the way.
To watch more English movies without subtitle
To read more books
To develop better relationships and keeping up their promises
To not to get angry and keeping cool myself at all times
To develop and incubate a project to get something tangible out of my knowledge
To participate in forums, conference and open source development
To make new friends
To donate more i did in 2008

Hope i achieve all of those listed above and others in this 2009.

How do i read a list of files that starts with a pattern?

Balaji Natarajan — Mon, 29 Dec 2008 04:50:14 +0000

I have been working with files quite a long time now and i got a requirement from my friend to read a list of files that starts with a specific pattern. For example, you must return a list of all files that starts with ’2008-12-’ in a directory. Thanks to DevDaily.com for it gave me a very good start from here. That program deals with reading a list of files that starts with an underscore “_”. Following is the program to read a list of files that starts with a specific pattern and here in this example you can pass the “pattern” as an argument.

public void readFiles()
{
	String pattern = "2008-12-";
	String startingDirectory = "C:/";
	String[] listOfFilesToParse =
                getListOfFilesMatchingPattern(startingDirectory,pattern);
}
String[] getListOfFilesMatchingPattern(String aDirectory,String pattern)
{
    class StartingWithFilter implements FilenameFilter
    {
	private String pattern;
	public StartingWithFilter(){
		pattern = "";
	}
	public StartingWithFilter(String s){
		pattern = s;
	}
	public boolean accept(File dir, String s)
      	{
        	if ( s.startsWith(pattern) ) return true;
        	return false;
      	}
    }
    return new java.io.File(aDirectory).
             list( new StartingWithFilter(pattern) );
}

Hope that Helps

Installed Ubuntu 7.04 and connected to Internet

Balaji Natarajan — Sat, 27 Dec 2008 06:55:40 +0000

Brought my virus attacked PC back to life by installing Ubuntu 7.04 (Fiesty Fawn).
Days ago
Earlier, I had many complaints reg. the speed of my laptop having only 256 MB RAM. I consciously chose the number of applications populating my task bar to cope up with my laptop’s speed. Yet the XP installed machine became slower and slower and one day i recognized that my PC is full of virus. The funniest part of it came when i typed “www.orkut.com”, the browser(Google Chrome) closed and an alert popped up saying “Orkut banned me!”, LOL
Rescue
I had lot of programs, my mini-project and stuffs like that in my pc to be recovered. I packaged all those important files, removed jars (which i download again from net) and uploaded in gmail. I suspect, since a keylogger virus is in my machine, my gmail password may be stolen. Anyway, i was through with the upload and then i asked my friend to change all my google account passwords and other important passwords from his pc.
Linuxomania
Sometime back, similar virus invasion happened to my desktop computer and i installed Fedora, but there was a problem in screen resolution. Yes, i accept adopting linux is not that much easy at first, it takes time to learn things, yet you must be patient. I can say, that linux is best for newbies if they are offered with an internet connection.
Now, i have to install some linux distro in my laptop. As i surfed through the cd bag, my hands found ubuntu cds (5.x and 7.04). First of all, i was afraid of 7.04 since i thought my 256 MB RAM will not be sufficient enough to install this. I just put it in my cd drive and reboot the machine. Minutes gone, it never turned up, at last a message said that there is a problem in starting GNOME. No thought of giving up, i put the 5.x version, it was through and i successfully formatted my system, installed the core system and yikes! the installation of additional packages went into a toss. Its because the cd is bit old and with few scratches.
Now, with this half baked installation, i can only login in text mode.
Installing Ubuntu 7.04
Never giving up again, i now put my 7.04 again. To my surprise, it booted up well, live cd thing did the magic and i am into GUI. Waugh! There was an icon in the desktop saying ‘install’. I clicked it and the installation was fine enough. I reboot the machine without cd and its worked fine. i logged into GUI without any hassle.
Problem in connecting to internet
As i told earlier, if you are new to linux, you must be gifted with internet connection to make your life easier in linux world. When i opened Firefox and fired a request to www.google.com it turned out with “server could not be found”. We have an adsl router at home with my brother’s laptop and mine in the network.
i just borrowed my brother’s laptop and sought help over the forums. Spent 2 hard days with it, at last i fixed the problem with my brother’s help. I did the following in succession and i don’t know what made it work.
1.Deleted iftab file from /etc and reboot the machine
2.sudo ifconfig eth0 192.168.1.1 up, then did ping 192.168.1.1 and it worked!
3.sudo ifconfig eth0 up
4.sudo ifconfig eth0 192.168.1.5 (192.168.1.5 is the ip i assigned to my machine)
5.Now pinged 192.168.1.1, 192.168.1.2(my brother’s laptop in the same network), ping www.google.com – all worked successfully and i am writing this post from Ubuntu.
Meanwhile, ensure whether you have plugged the ethernet cable into your machine, coz, i wasted some 2 hours troubleshooting my pc without ethernet cable plugged in. LOL. :> Also some switching off/on the router helps in other cases.

Podcast on Ajax – Part 1 – Introduction to Ajax

Balaji Natarajan — Sun, 07 Dec 2008 17:19:19 +0000

Whoa! At last i did it. I came up successfully with my first ever podcast on Ajax. With lot of mistakes, uh-uh s, discontinuity, I am sure you’l like it anyway. My apologies too for the mistakes made.

I must thank Derek K Miller from Penmachine from where i got the introductory and conclusion music for the podcast. Music track used for this podcast is “More/Less Red than red”.

Your comments are most welcome that will help me to improve in the podcasts to come.

Dealing with the Design Patterns

Balaji Natarajan — Sun, 30 Nov 2008 16:52:13 +0000

Design Patterns are the best way to deal with your OO goodness! Yes, right after you have learned what inheritance is, what polymorphism is, what interfaces are, next, on way the way is to learn how better to use them together to realize a real world model. Often design pattern are given least importance and we stick to the normal way of coding things, i.e., procedural way. As a layman corolory, having a sharp chisel and hammer will never make you a skillful carpentar. You must know how well to use them and you must have a design in mind. That’s an OO thinking.

Well, if i give you a job of constructing a bridge across the river in your town, would you be taking the offer, definitley yes, even if you dont know how and where to start. As we are Newton and Edison, first, you will be resorting to already reaserched solutions because they were proven to be successful. Similarly, when coming to OO and modeling, there are, believe me!, pre-built solutions and they are called “Design Patterns”. Design Patterns give you a direction and those are all not a concrete implementation. They may be language and platform independent and applicable to a wide variety of problems.

I am going to recommend this book very strongly, yes, it is Design Patterns: Elements of Reusable Object-Oriented Software by Erich Gamma and others. Needless to say, it is a bible and not tied to a specific language or platform. Ofcourse, the examples are coded in C++ but i dont think it would be a difficult one to pick up since C++ is the start of moder OO concepts.

I am working on Java and we have design patterns specific to Java language but does not take any considerable deviation from what you may read from the aforementioned book. Patters related to Java are called as Core J2EE Patterns and you can find an excellent reference to it here at sun website. http://java.sun.com/blueprints/corej2eepatterns/Patterns/index.html .The patterns are conceptually related and you can click on any pattern to know more about it in detail. There is also forum dedicated to Patterns and OO by Sun and you can enjoy participating in this forum here http://forums.sun.com/forum.jspa?forumID=425

I have an idea of doing case studies in every pattern with examples and come up with a blog for each one. So, wait for it!