Pages

Showing posts with label java tutorial. Show all posts
Showing posts with label java tutorial. Show all posts

Thursday, 13 December 2012

Overview of Client tier, Presentation tier, Business tier, and Resource tier patterns



http://best-study-materials-java.blogspot.in/


 Java originally made its debut on client machine and browser. With increasing third party support in java 2 , J2EE (Java 2 Enterprise Application ) technology is widely being accepted for server side enterprise applications. J2EE architecture is logically divided in to many tiers such as client tier, presentation tier, business tier, and database tier. It supports many APIs and protocol that provides the functionality to provide multi tier web application.

 J2EE Client Tier
J2EE application supports many types of clients they can run on laptop, desktop, palmtop, or on cell phone. They may range from desktop big browser to cell phone mini browser, all they connect to world wide web from their intranet, through a wired network or wireless network.

 Java client tier consists of application running on desktop, laptop etc  and they connect to the application server directly using HTTP, FTP etc protocol. This requires only that the application must installed on the client machine. The web browser is the client application software used to connect to the application server.

 J2EE Presentation Tier

 A J2EE presentation tier consists of applications that prepare /format data to deliver the client tier, and and takes data from client side  to send back end business process. This tier typically consists of J2EE components such as servlet, JSP that prepare data in HTML or XML  to deliver to the client. This tier also provides portal services that can provide secure, customize and personalize  business service.

 The presentation tier components are often reusable components that can be customized and plugged into an application.

 Business Tier
The business tier performs the main function of the application by implementing the business logic on the data processing, coordinating among multiple user and managing database resources. This tier consists of tightly coupled components such as EJB components or message driven beans. It performs the business work and send to the presentation tier for client side or send to the database tier or data tier. The EJB can be used to solve business logic, and it is used to create business object .

 Resource Tier/ Data tier

 This tear consists all the data/ information related to the business logic. The data may be be resource or directory information stored in Lightweight Directory Protocol or it can be persistent application data stored in the database management system. Generally the data-tier is installed on the separate machine. All the information stored on this tier are very important for organization so it may kept to another place.


 java architecture

 java architecture tutorial

 java architecture interview questions

Posted by at 2 comments:
Labels: , , , , ,

Tuesday, 11 December 2012

An Introduction to the Java Programming Language History of Java



Every great Dream begins with a Dreamer. 
Always remember, you have within you the 
Strength, the Patience, and the Passion 
to reach for the 
Stars to change the World.


Java
java programming
java games
learn java
java script
java 64 bit
java update
java tutorial
java api






An Introduction to the Java Programming Language

History of Java 

In 1991, a group of Sun Microsystems engineers led by James Gosling decided to
develop a language for consumer devices (cable boxes, etc.). They wanted the
language to be small and use efficient code since these devices do not have
powerful CPUs. They also wanted the language to be hardware independent since
different manufacturers would use different CPUs. The project was code-named
Green.
These conditions led them to decide to compile the code to an intermediate
machine-like code for an imaginary CPU called a virtual machine. (Actually, there
is a real CPU that implements this virtual CPU now.) This intermediate code
(called bytecode) is completely hardware independent. Programs are run by an
interpreter that converts the bytecode to the appropriate native machine code.
Thus, once the interpreter has been ported to a computer, it can run any
bytecoded program.
Sun uses UNIX for their computers, so the developers based their new language
on C++. They picked C++ and not C because they wanted the language to be
object-oriented. The original name of the language was Oak. However, they soon
discovered that there was already a programming language called Oak, so they
changed the name to Java.
The Green project had a lot of trouble getting others interested in Java for smart
devices. It was not until they decided to shift gears and market Java as a language
for web applications that interest in Java took off. Many of the advantages that
Java has for smart devices are even bigger advantages on the web.
Currently, there are two versions of Java. The original version of Java is 1.0. At
the moment (Nov. 1997), most browsers only support this version. The newer
version is 1.1 (in addition 1.2 is in beta). Only MS Internet Explorer 4.0 and Sun's
HotJava browsers currently support it. The biggest differences in the two versions
are in the massive Java class libraries. Unfortunately, Java 1.1 applets will not run
on web browsers that do not support 1.1. (However, it is still possible to create
1.0 applets with Java 1.1 development systems.)
Basics of Java Applications




There are 2 basic types of Java applications:
standalone 
These run as a normal program on the computer. They may be a simple
console application or a windowed application. These programs have the
same capabilities of any program on the system. For example, they may read
and write files. Just as for other languages, it is easily to write a Java console
program than a windowed program. So despite the leanings of the majority
of Java books, the place to start Java programming is a standalone console
program, not an applet!
applets
These run inside a web browser. They must be windowed and have limited
power. They run in a restricted JVM (Java Virtual Machine) called the
sandbox from which file I/O and printing are impossible. (There are ways
for applets to be given more power.)
Development Tools
There are many development tools for Java:
Sun's JDK
Sun's Java Development Kit has two big advantages:
1. It is the most up to date.
2. It is free!
Its main disadvantage is that it only includes command line tools, no IDE. Many
Java books include this on a CD-ROM.
Borland's JBuilder
It contains an IDE and supports Java 1.1
MS Visual J++
It contains an IDE, but to my knowledge does not yet support Java 1.1
Symantec's Visual Cafe
It contains an IDE, but no Java 1.1 support yet.
Compiling and Running a Java Standalone Application
Hello, Java program
Here is a short Java program:
/* A simple Java program */public class Hello {
  public static void main( String args[] )
  {
    System.out.println("Hello, Java");
  }
}
Creating a Java source file
Java source files must end in an .java extension. The root name must be the same
as the name of the one public class in the source file. In the program above, the
class is named Hello and thus, the file must be named Hello.java (Yes, case is
important!).
Just as for other languages, any text editor can be used to save the text of the
program into a text file.
Compiling a Java source file
Sun's JDK includes a Java compiler named javac. To compile the above Java
program one would type:
javac Hello.java
If successful, this creates a file named Hello.class If not successful, it prints out
error messages like other compilers.
Running a Java program
To run a standalone program, Sun's JDK provides a Java interpreter called java.
To run the .class file created above, type:
java Hello
Note that .class is not specified!
The output of running the above program is simply:
Hello, Java


Java Programming 

Classes and objects
Java is an object-oriented language (like C++). An object is an abstract thing in a
program. Generally, objects are not completely different from each other and can
be classified into like groups. The group an object belongs to is called a class.
Objects in the same class share two attributes:
1. A state space (i.e., the set of all possible states of the object)speak).
Consider the Vector class that the Java class library provides. A Vector object is
basically an array that grow or shrink in size dynamically. It's state is defined by:
1. The elements stored in their given order
2. The number of elements stored
It's methods include:
addElement()
Adds an element to end of the vector increasing its size by 1
insertElementAt()
Adds an element at a specified position in the vector. The elements above
are shifted up one position and the size is increased by 1.
setElementAt()
Stores an element at a specified position in the vector. The previous element
value is lost.
removeElementAt()
Removes an element at a specified position. The elements above are shifted
down and the size is decreased by 1.
elementAt()
Returns the element at a specified position.
size()
Returns the current size of the vector.
If v is an object of type Vector, then a method is invoked on v by the following
syntax:
v.method-name(method-arguments);
For example, to add another object x to the end of v use:
v.addElement(x);
In an object-oriented language, one looks at the statement above as a request for
the v object to add the object x to the end. That is, invoking a method sends a
message to the object being acted on. The message asks the object to perform
some operation.

Primitive types 
Java also supports some primitive types that are not classes. These types are
similar to the primitive types of C:
byte
a single byte (8-bit) signed integer
char
a two-byte (16-bit) Unicode character
short
a two-byte (16-bit) signed integerint
a four-byte (32-bit) signed integer
long
an eight-byte (64-bit) signed integer
float
a four-byte floating point number
double
an eight-byte floating point number
boolean
a type of variable that may be either true or false
Defining a class 
The general form of a class definition is:
public class class-name {
  /* class state definitions */
  /* class method definitions */
}
Here's an actual example that creates a Queue class:
public class Queue {
  /*
   * the state of the Queue is represented by an internal vector instance
   * (The private indicates that this part of the Queue is only
   * accessible by the methods of the Queue class. This implementation
   * hiding is known as encapsulation.)
   */
  private Vector v;
  /*
   * This is a constructor - it is used to create a new instance of
   * a Queue. The public indicates that this method is available for
   * use by any class.
   */
  public Queue( )
  {
    v = new Vector();      // construct the internal vector object
  }
  /*
   * This method adds an element to the queue
   */
  public void enque( Object obj )
  {
    v.addElement(obj);     // add to end of internal vector  }
  /*
   * This method removes and returns an element from the queue
   */
  public Object deque( )
  {
    if ( v.size() > 0 ) {
      Object obj = v.elementAt(0); // read object from front of vector
      v.removeElementAt(0);        // remove object from front of vector     
      return obj;                  // return object
    }
    else
      return null;                 // if queue empty, return special null value
  }
  /*
   * This method returns the number of elements in the queue
   */
  public int size()
  {
    return v.size();               // return size of internal vector
  }
}
Using classes




To create an instance of a class, the instance must be constructed by a special
method called a constructor. Constructor methods always have the same name as
the class. To create a queue, one would type:
Queue q = new Queue();
The new keyword says to create a new object. The instance variable q can be used
to refer to this object. Thus, the statement:
q.enque("one");
says to enque the string "one" in the Queue referred to by q.
It is often stated that Java does not have pointers and technically this is true.
However, class reference variables act like pointers (or really more like reference
variables in C++). Assigning class instance variables do not create new instances.
For example:
  Queue q1 = new Queue();     // q1 refers to created Queue object
  Queue q2 = q1;              // both q1 and q2 refer to *same* object!
  q1.enque("one");
  q2.enque("two");  System.out.println((String) q2.deque() );   // prints out "one", not "two"
Non-class instance variables (like int variables) work just as in C, assignment
does copy values of these.
These rules have important consequences for parameters of methods. For
example, consider the following method call and code:
  // method call
  int x = 5;
  Queue q = new Queue();
  method(x,q);
  ...
  // method code
  void method( int xp, Queue qp )
  {
    xp++;               // changes local var xp, not x!
    qp.enque("word");   // adds "word" to the single object referenced by
                        // q and qp
  }
Thus, primitive type instances are always passed by value and class instances are
always passed by reference.
Static methods and state
Normally a method acts on a single object (or instance) of a class. However, it is
possible to define a method that acts on a class itself instead of a particular
instance of the class. These classes are declared static.
The static keyword can also be used on the state variables of the class with a
similar result. The variable becomes a property of the class itself and not any
particular instance.
Static methods can only access the static variables of its class, not the non-static
variables. Here's a very simple example:
public class StaticTest {
  public int ns;         // ns is a normal non-static variable
  public static int s;   // s is a static variable
  public void ns_method() // normal non-static method
  {
     ns = 3;             // can access ns
     s  = 5;             // and s
  }
  public static void s_method() // static method
  {    s = 7;               // can *only* access static s!
  }
}
Since static methods and instances are properties of a class and not an instance of
a class, they are invoked on the class itself. For example, to call the static method
above, one would type:
StaticTest.s_method();
Now we are ready to understand our initial Java program:
public class Hello {
  public static void main( String args[] )
  {
    System.out.println("Hello, Java");
  }
}
System is a name of a class in the Java class library. System.out refers to a static
object in the class that represents the console screen. The println() method is
used to tell System.out to display a string on the console. Note that main() is a
static method.
Object-Oriented Programming and
Inheritance
The preceding section looked at classes from the purely Abstract Data Type view.
The object-oriented paradigm goes further by looking at relationships between
different classes. Often different classes have an IS-A relationship. This type of
relationship exists when one class is a more specialized version of another.
For example, what if one needed a searchable vector class. The Vector class does
not include a method to search for objects inside an instance. However, one could
create a new vector class that performed just like the old Vector class, but directly
supported searching.
The wrong way to do this is to create a new SearchableVector class from scratch
that contains a internal Vector (like how the Queue was implemented). This
would require one to re-specify each of Vector's methods for SearchableVector
(there are many more methods than the one's specified above!).
The right way is to use Java's inheritance mechanism. The SearchableVector
class is an extension of the Vector class. Or, in other words, a SearchableVector
IS-A Vector. A SearchableVector can do anything that a Vector can do, plus
more. Java allows one to simply define a new class that extends the features of an
existing class. The new class automatically has all the state and methods of the
existing class. The syntax is: class subclass extends superclass {
  // new features of subclass
}
where subclass refers to the new class and superclass refers to the existing class
being extended. All classes in Java are extensions either directly or indirectly from
the Object class. Here is the definition of the SearchableVector class:
public class SearchableVector extends Vector {
  /* search returns the index of the object if found,
   * else -1
   */
  public int search( Object obj )
  {
    for( int i = 0; i < size(); i++ )
      if ( elementAt(i).equals(obj) )
        return i;
    return -1;
  }
}



In the limit of the for loop, the size() method for a Vector is called. No object is
specified since search() itself is a method and so size() acts on the same object
that search() does. The object a method acts on can be referred to by the this
keyword. The size() call in the for loop could be replaced with this.size() with
the same effect.

Regards :

Er Neha Patidar [ BE ] 
Software Engineer / Webmaster
www.AeroSoftCorp.com 
www.AeroSoft.in
www.AeroSoft.co.in
www.AeroSoftseo.com
On Line Assistence :
Gtalk : nehap.AeroSoft@gmail.com
Y! Messenger : nehap.AeroSoft@yahoo.com
Rediff Bol : nehap.AeroSoft@rediffmail.com
MSN : nehap.AeroSoft@hotmail.com





 KPC Systems & Power Solutions, Best Inverters dealers, UPS dealers ...

kpc-power.co.in
KPC Systems & Power Solutions, the most prestigious and progressive trader of reliable andthe batteries for all automobiles, UPS, Inverters, Industrial and other .

Airline Transport Pilot License | Aviation Career Guide

www.philippinespilot.com
Airline Transport Pilot License - information on flight school training, studying for an aviation degree, military flying and all the certificates including PPL, CPL ...


New Flight Servives |Career in Airlines | Career in New Flight ...

newflightservices.com
NEW FLIGHT SERVICES ISO 9001:2000 CERTIFIED AVIATION ORGANIZATION . Best Pilot training in Philippines with Us


AeroJobMark | Best Pilot Jobs Airplane | Best Pilot Jobs Airplane

www.aerosoftseo.com/aerojobmark/home
AeroJobMark , Best Pilot Jobs ,Airplane,Aviation, jobs, Airline, Pilot, employment



 www.MissionToCanada.com | Mission To Canada

missiontocanada.com
Everybody has dreamt once of becoming a pilot during their childhood and few are able to make it possible. Becoming a Pilot takes lot of pain and labour, as it is one 

AeroSoft Corp Indore, Home, AeroSoft Corp Best Aviation SEO India ...

www.aerosoftcorp.com
AeroSoft Corp, Aviation Company, AeroSoft Aviation SEO Company, information of aerosoft seo company, information of aerosoft aviation seo company

1. 

A-1Soft Corp Indore, Asia's Best Travel SEO and KPO Services ...

www.a-1soft.com/
A-1Soft Corp, Pioneer in Virtual Travels And Tourism Market in Asia, Travels And Tourism Company, A-1Soft Travels And Tourism SEO Company, information of ...




1. 

Best GolGappa, Asias Best B2B Portal, Pani Puri, Pani Poori,recipes ...

golgapppa.com/Share
Asias Best b2b portal, GolGappa, Pani Puri, Pani Poori,recipes,instructions, ingredients, golgapppa.




1. 

Wel come To Asiatic Air | Pilot Training Services | Jobs for Freshers ...

www.asiaticair.co.in/Share
Wel come To Asiatic Air | Pilot Training Services, helicopter pilot training in india, free pilot training in india, pilot training in india fees,commercial pilot in india, ...

Wel come To Asiatic Air


Wel come To Asiatic Air | Pilot Training Services | Jobs for ...

About Us


About Us. Asiatic International Aviation Corp. Asiatic ...
More results from asiaticair.co.in »

2. 

Best MCA study Material| MCA books | Best MCA college |Top ...

aerosoftseo.com/best-study-material-mca/Share
MCA | BE |BCA| MCA notes | MCA study Material| MCA books | Best MCA college |Top Colleges of India| | Notes |Notes for mca students |MCA Syllabus| MCA ...




Best GolGappa, Asias Best B2B Portal, Pani Puri, Pani Poori ...

www.golgapppa.com
Asias Best b2b portal, GolGappa, Pani Puri, Pani Poori,recipes,instructions, ingredients,golgapppa


Welcome to AeroSoftSEO - AeroSoft Corp | Best Aviation SEO ...

www.aerosoftseo.com
Mission Vision Passion DBA JHR; B2B B2C OJT Blog FAQ; Search Vender Term Resources; Welcome to AeroSoftSEO. AeroSoft Corp is a very small sized newly establishing ...
Posted by at 20 comments:
Labels: , , , , , , , , , ,
Subscribe to: Posts (Atom)