• What is Cloud Computing?

• Cloud Computing can be described as the modern day Internet Computing and it is mainly enabled by virtualization and we can say it is an adaption of virtual computing ,because everything depends and runs on the Internet!Imagine you have a website and you started promoting it and by god's grace it has clicked and you got some huge amounts of traffic.So,obviously you have to maintain your web-server with increase in your site's popularity.There may be one state where you may fail to maintain your server as  effectively and as consistently compared to the earlier times,which may result in less number of hits for the site,many people may find difficulties in accessing your website and many other problems.One solution is to buy more and more number of servers which involves increased cost and maintenance.
• Take an other scenario , where your company has a website which attracts seasonal traffic from the public like an examination results portal.There will be huge amounts of traffic when the results are out and to handle that traffic the company must buy more servers but in the rest of the time the site doesn't get too much attention.So , the company need to pay for the server and its maintenance even though there is not much traffic. We just cant throw away the servers once we buy and set them up and running.
• Cloud Computing provides easy solution for the above problems decreasing the cost of setting up and maintaining the servers , site and application of an end-user/organisation.

source getty images

• Cloud computing involves sharing of  many computer resources like software,servers etc;which are useful for the software development.These resources are shared between the computers all over the world by using the data centers which will be accessed through Internet and is known as "Cloud".There are many organizations which call themselves as Cloud Service Providers( Google,Amazon,Microsoft,vmware etc) which provide these infrastructure and software in the form as a service through Internet or as we call in this context Cloud.The main idea of Cloud Computing is we outsource our application/web site to the Cloud Providers and use their infrastructure to run our applications.
• So how can a cloud service provider help solve the above problems for an organization?
  
  Cloud Computing follows some important capabilities which help solve the above problems:
  1.Elasticity : As the name suggests it means being flexible, when your application needs to serve the traffic which needs 100 servers the cloud can scale up and give access to 100 servers at peak time and if you need only 1 server to just keep the site running without any huge traffic you will get only 1 server. You cant get this kind of flexibility or scalability when you are hosting the application/ web site on your own.
  
  2.Pay-As-You-GO: So previously you bought 10 servers to maintain the traffic for your website which will last for only 2 months and in the rest of the year you just need 2 servers to maintain the website leaving those additional 8 servers ideal. Cloud computing solves this problem as you can pay for only the number of servers or computing resources you are using i.e. Pay for only 2 servers when your site is getting less traffic and 10 servers at peak time. This is just like paying for a Cab or Electricity , when you want to go somewhere you hire a cab and pay for the ride depending on the distance traveled,and you pay for the electricity as per your usage.
  
  3. Self Service and Instant Access( ON/OFF): When you want to setup the servers on your own you buy the infrastructure and take some time to get them ready.But in the case of cloud-computing, the cloud providers will give the access to the cloud through a terminal or console which we can access through our computer. You can instantly order the computing power when you are in need and just turn them off like an electric bulb when you are done.
  
  These are the main reasons why the cloud computing became so huge recently. Hope this makes sense till now. But you may ask what does cloud computing mean to me? How it is helpful ? The answer is, it takes many forms and is helpful depending on what your need is.

• If you are a Business Professional or System Administrator : Cloud computing is all about outsourcing your application and data to utilize the computing power like infrastructure, hardware, servers etc; You move away from the servers you are paying to maintain the website and access the infrastructure of the cloud provider. This is called Infrastructure as a Service ( IaaS ). You will be billed according to the number of CPU hours and the usage of the website. Majority cloud providers in this domain are Amazon Web Services (which provides many services like Amazon EC2 and S3), Google (Google Compute Engine) , Microsoft (Azure), Red hat  vmWare etc;
• If you are a Developer or an Architect : You need to develop applications or think of a strategy to migrate the existing in-house applications to scale and to leverage the service of cloud. All you need is a platform(Java, .Net , PHP , Ruby etc). Providing this is called as Platform as a Service ( PaaS ). This service will provide a Platform and a set of development tools knows as SDK to develop or migrate applications to leverage the cloud services and infrastructure. The major provider in this service are Amazon(Amazon Web Services Elastic Beanstalk), Google ( Google App Engine), Microsoft Windows Azure, Heroku, AppHarbour,CloudFoundry etc; If you are a developer these services provide some exciting features. All you need to do is download the SDK from the site, write some code and deploy that to the server.Voila!! You can access your application anywhere in the internet! Its that easy.
• If you are an End-User : You need a variety of application in your day to day life. But in some situations you may need to worry about many things to access that applications like the application may not run on your hardware, you cant access your application data in another device or at your workplace.So instead of buying the software and installing it on your device, you can purchase a monthly,weekly or yearly subscription of that application and access that application on your web browser without worrying about your hardware. You can use it on your PC when you are at home, on your laptop when you are at your workplace, on your mobile phone or tablet well where ever you may be. This is called providing Software as a Service ( SaaS ). For example, instead of buying Microsoft Office license and installing it on your computer you can just simply use Office Cloud365 service provided by Microsoft by paying monthly subscription as per your usage. One major advantage is you can use the brand new versions of the software with updated features every time unlike the software you bought for some huge money.

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package mediaplayer;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
import javazoom.jlgui.basicplayer.*;
/**
 *
 * @author Administrator
 */
class JavaMediaPlayer extends JPanel implements BasicPlayerListener{

    private JProgressBar jpb;
    private JButton play;
    private BasicPlayer player=new BasicPlayer();;
    private String imagePath="images/";
    private static int p=0;
    private static boolean playBoolean=true;

    JavaMediaPlayer(){
        //setLayout(new FlowLayout(FlowLayout.LEFT,3,3));

        setLayout(null);

        player.addBasicPlayerListener(this);

        play=new JButton(new ImageIcon(imagePath+"pause.png"));
        play.setToolTipText("pause");play.setBounds(2,2,20,20);

        play.addActionListener(new ActionListener(){
           public void actionPerformed(ActionEvent ae){
               if(playBoolean){
                   pausePlaying();
                   play.setToolTipText("Play");
                   play.setIcon(new ImageIcon(imagePath+"play.png"));
                   playBoolean=false;
                   return;
               }
               if(playBoolean==false){
                   resumePlaying();
                   play.setToolTipText("Pause");
                   play.setIcon(new ImageIcon(imagePath+"pause.png"));
                   playBoolean=true;
                   return;
               }
           }
        });

        jpb=new JProgressBar();
        jpb.setBorderPainted(true);
        jpb.setBounds(25,2,280,20);

        add(play);
        add(jpb);
    }

    public void startPlaying(String fileName){
        try{
            play.setIcon(new ImageIcon(imagePath+"pause.png"));
            play.setToolTipText("Pause");
            playBoolean=true;
            player.open(new File(fileName));
            player.play();//actually play file
        }
        catch(Exception d){
            System.out.println(d);
        }
    }
    private void pausePlaying(){
        try{
            player.pause();
        }
        catch(Exception e){
            System.out.println(e);
        }
    }
    private void stopPlaying(){
        try{
            player.stop();
            jpb.setValue(0);
        }
        catch(Exception d){
            System.out.println(d);
        }
    }
    private void resumePlaying(){
        try{
            player.resume();
        }
        catch(Exception d){
            System.out.println(d);
        }
    }

    public void opened(Object arg0, Map map) {
        String k=map.get("audio.length.frames").toString();
        jpb.setMaximum(Integer.parseInt(k)-15);
    }

    public void progress(int arg0, long arg1, byte[] arg2, Map map) {
         String s=map.get("mp3.frame").toString();
         int k=(p-(Integer.parseInt(s))*(-1));
        jpb.setValue(k);
    }

    public void stateUpdated(BasicPlayerEvent bpev) {
       if(bpev.getCode()==BasicPlayerEvent.STOPPED){
           // Something here
       }
    }
    public void setController(BasicController arg0) {
       // throw new UnsupportedOperationException("Not supported yet.");
    }
}

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package mediaplayer;

import javax.swing.*;

/**
 *
 * @author Tutorial Jinni
 */
class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        JFrame f=new JFrame();
        JavaMediaPlayer jmp=new JavaMediaPlayer();
        f.add(jmp);
        f.setDefaultCloseOperation(3);
        f.setVisible(true);
        f.setSize(330,60);
        f.setTitle("Java Media Player - Tutorial Jinni");
        jmp.startPlaying("Song-location.mp3");
    }
}

• This Mobile comes with Android 2.1 OS
• TFT LCD Display with 2.8'' 240x320 pixels.
• 2MP camera with LED Flash.
• Google Mobile Service,Android Market,Touchwiz 3.0.
• Wi-Fi, Bluetooth 2.1, A-GPS .

• Floating Point Datatypes(float,double) are used to store the decimal type(fractional type) values.The memory size of the datatypes of float,double are 4,8 bytes respectively.The floating point literals float must end with ' f '.And double literal must take a precission of two places or else there will be a Loss In Precesion Error by compiler.

• Character Datatype(char) are used to store single Unicode characters.The memory size is 2 bytes.
• Boolean Datatypes are used to store the values which are either true or false .

• Primitive or Non Reference Datatypes :byte,short,char,boolean,float,int,double,long( ordered in ascending and alphabetical order)
• Reference Datatypes : Class type, Interface type,Array type,String Type.

• Class is the central point of OOP and it is collection of objects and data and methods exhibiting certain kind of behaviour.In the classname every word must start with a "capital letter" Ex: HelloWorldJava.

• Objects are the basic unit of OOP and basic runtime entities expressed as variables and methods.
• Methods in Java determine the behaviour of the object.The methodName must start with a ''lowercase letter'' and the preceeding word in the method name must be a "capital letter".

• Abstraction is the process of hiding the unnecessary or secret details and exposing the essential features of an object.This concept is mainly used by classes.The above image shows the abstraction of a Car class which hides the unnecesarry details and exposes the details like Change gears,Brake,Change cadence.
• Encapsulation is the ability of an object to bind the data and methods together.The Accessor and Mutator methods exhibit encapsulation.The above image also demonstrates the Encapsulation process.
• Data Hiding is the ability of the objects to shield the variables from external access.
• Polymorphism.Let us make this straight.Polymorphism is the ability of an object to take one or more forms.

• Create a Source file : The source file contains all the code of our program written in Java.You can generally use a text editor like Notepad for creating the source file.After writing the code just save it in the .java format.Example: Sample.java
• Compilation of the Source file : Now the created source file(Sample.java) must be compiled to generate the ByteCode.It will be compiled by javac compiler which can only be understood by Java Virtual Machine(J.V.M).The command for compilation is javac Sample.java
• Run the java file : The java application can be executed by J.V.M by using java command.The command for running the file is java Sample.

/**
 * The HelloWorldApp class implements an
 * application that simply prints
 * "Hello World!" to standard output.
 */
class HelloWorldApp {
    public static void main(String[] args) {
        System.out.println("Hello World!");
        // Display the string.
    }
}

Then, save the file as HelloWorldApp.java and exit NotePad.

Compilation of the Source File

Bring up the command prompt and navigate into the source file location.

Then,type the command

 javac HelloWorldApp.java


Run the Java File

To run the Java File,after compilation you can see the output by typing the command.
 java HelloWorldApp

Explaining HelloWorldApp


The HelloWorldApp source file contains Multiple line Comments which are useful in the development phase of the program.Its a good habit to Comment your programs as it is useful for others to know about your program.
HelloWorldApp class begins with the keyword class(A brief explanation will follow the next posts) which is embeded between the two curly braces " { } ".
                    class HelloWorldApp{ }
Main Method is the essential method for every class.It is the entry point into the program.It is named as "public static void main(String [ ]  args)".The main reason behind this is:
            -> Why main must be declared as public?
            A). main() is invoked by JVM(i.e. J.V.M will access the main() method in our class)As JVM is outsider,it does not belong to our program package.So,inorder to access main outside our program we declare it as public.Or else we will get a compilation error known as main method not public.

           -> Why main must be declared as static?
           A).If a method is declared as static in the class we can call it with using classname.methodName(); So in order to call the main method it must be static.

          -> Why main must be declared as void?
          A). A void keyword means it returns nothing.JVM expects nothing when calling the  main method.So it is named as void. 

This sums up the introduction to the basic Java Program.

This is the introductory Hello World App.Stay Tuned for more Tutorials!

Au Revoir!!

• At this moment ,Sun Microsystems,Inc. designed a programming language called Oak by James Gosling and Patrick Naughton which is renamed to Java in 1995.

• How Java Works?

This ByteCode obtained from the compiler is executed in the Java Virtual Machine(J.V.M) which is the Java run time system which also acts as an interpreter for the ByteCode     .      

Characteristics of Java       

• Simple.
• Object Oriented.
• Distributed.
• Interpreted.
• Robust.
• Secure.
• Architecture Neutral.(Platform Independency)
• Portable.
• High Performance.
• MultiThreaded.
• Dynamic.

Closer Look at Java Source File

     A java code is written mainly in the text editors or an IDE(Integrated Developer Environment).If you are at learning stage I suggest you to start with a text editor like Notepad,EditPlus,etc;

• Java Source File is categorised into four sections.They are:Package section,Import section,Class/Interface section,Comments which are further divide into Multiple Line Comments and End of Line Comments.You can refer the above picture to make it clear.

Here is a small Video on Basic Java Development to wind up this post.

Hello World Program!