Defination of API

An API is a collection of packages. A packages is a collection of classes , interface and sub packages. A sub package is a collection of classes , interfaces , and sub packages e.t.c .

D.  Java programing environment contains user friendly syn taxes so that one can develop effective applications compared to all the programing languages Java syn taxes are so easy .

2. Platform Independent :-

A language or Technology is said to be platform independent if and only if whole applications must run on every operating system without considering their vendors . To say a language / Technology is platform independent then it has to satisfy two properties . They are

a. The language data types " Must take " same amount of memory space on every operating system .

b. the language must contains some special programs which will convert from one understanding form of one as to another understanding form of another OS.


The C, C++ applications are platform dependent because

- The C , C ++ data types will take different memory spaces on different O.S.

- The C , C++ software are not containing any special programs to convert from one understanding form of one O.S to another understanding form of another O.S .

     The Language like Java and their applications are treated as platform independent, because of

- Java language  data types will take same amount of memory space on every O.S .

- Java software ( JDK ) contains some special programs for converting one format of one O.S to another format of another O.S.




 

 

Define / What is a Garbage collector

A Garbage collector is the system background Java program which is running along with the regural Java program which is running along with the regular Java program for collecting unused / Unreferenced memory space . for improving the performance of Java application . Garbage collector program running internally along with our Java program for regular periodical intervals of time .

NOTE : Java programing language does not contain destruction ( like c ++ ) . In place of destruction we have a garbage collector program .

C Java programming contains rich set of API ( Application programming Interface ) .   

Define Byte Code and JVM

Byte code is the set of optimized instructions generated by Java Compiler during Compilation Phase . The nature of the byte code is so faster than ordinary pointer code. JVM is the set of programs developed by sun micro system and supplied as a part of JDK for reading line by line of byte code and converting into native understanding of O.S .

        To complete the Java program execution , it has to undo compilation phase and interpretation phase. Hence Java programing language is one of the compiler cu interpreted programing language.

Java Programing environment is containing in build garbage collector program for collecting unused / Un reference memory locations . So that Java programmer is totally free from writing performance oriented programs. Performance of the Java program taken care by Java software.
          

Features / Buzzwords Of JAVA :

Features of any programming Language is nothing but the services or basic facilities provided by the language to the industry programmers . The language JAVA provides 13 features . They are :

1. Simple
2. Platform independent
3. Architectural neutral
4. Portable
5. Multi Threaded
6. Networked
7. Distributed
8. High Performance 
9. Interpretedget
10. Dynamic
11. Robus ( strong )
12. Secured
13. Object Oriented Programing Language

Simple : Java is because of the following factors

a. Java Programming does not support pointers . Hence we get less application development time and less execution time , because magic of byte codes .

NOTE : Whenever we write any Java Program, We save that program on file name with an extension . Java the following diagram gives  the Java Program execution

Phases

x. Java       --------   x. class   --------  Native Under   --------  Result
                                                           standing form
                                                                  of OS
 

Difference between http and FTP

Http

#  It is one of the TCP protocol .

# http is one of the stateless protocol .

# http is the one of the acknowledgement oriented protocol .

FTP

# It is one of the UDP protocol .

# It is one of the state ful protocol .

# FTP is one of the non acknowledgment oriented protocol .


-> A stateless protocol  is one which maintain an identify of a client for a period of time .

ex : http

-> A stateful protocol is one which maintains an identify of client forever .

ex : FTP

NOTE : The following tables gives Java Technology version and its language version comparison .



Technology Version                            Language Version                  Comparison 

   JAVA                                                       JDK 1.0                                        Tortoise
                                                                   JDK 1.1                               


   JAVA 2                                                    JDK 1.2                                         Dog
                                                                   JDK  1.3                                        Horse

   JAVA 5                                                    JDK  1.5                                        Tigers ( by SUN )
                                                                   JDK   1.6                                        Mustand ( Ford Icon )

As on today J2SE must be taken as J.E similarly J2EE as JEE and J2ME as JME .

History of JAVA

When we are learning any programming language newly , it is highly recommended for the programmer to learn the history of the language .
   
We are learning Java language and whose history will be given in the following points .

1. Java is a programing language / technology used by the industry for development of client distributed applications by making use of client server architecture .

2. Java language developed of Sun Micro System in the year 1990 by a person called James Gosling and Others.

3. What ever the trial version developed and released in the year 1990 , it was name as " OAK " , which is the original name of Java and it has taken 18 months to develop . Scientifically the original name of OAK is one of the Tree name .

4. Originally Sun Micro System is one of the academic university ( Standard University Network ). Sun developed rules for java under the guidance of James Gosling and those rules are program metrically implemented developed / define by Java Soft INC , USA which is the software division of sun micro system only.

5. The Software OAK is solving some of the problems in the industry and some of the problems not solved , in other words. OAK software is not completely solving industry problems . Hence the Software OAK revised by Sun Micro System in the year 1995 and released to the industry on the name of " JAVA " ( Scientifically it is one of the coffee seed name ).

6. The Software Java is available in the industry in three categories . They are :

a. J2SE    ( Java 2 Standard Edition )
b. J2EE   ( Java Enterprise Edition )
c. J2 ME ( Java 2 Micro / Mobile Edition )

J2SE : It is used by the industry for development of client side applications .

J2EE : It is used for developing server side applications to exchange the data between J2SE and J2EE applications we use a protocol called http .

J2ME : It is used for developing Mobile wireless applications by using a protocol called WAP ( Wireless Access / App Protocol ) .

Architecture Required for Development of Distributed App :

According to industry standards , distributed applications will be developed by a well know architecture called client -server architecture .

According to industry standards client server architecture having 3 categories . They are

1. Two 2 - Tier Architectures :

 It contains
  - Set of Client Programs
  - Set of server Programs

2. 3 - Tier Architectures :

   It contains

     - Set of client Programs
     - Set of server Programs

3. n - Tier Architecture :

    It contains

     - Set of client Programs
     - Set of Firewall Programs
     - Set of server Side Programs
     - Set of Database Software

The Following diagram used under gives diagrammatic view of client server architecture.


Client   : A client is the Java Program which always makes a request to the server to get the services .

Server   : A Server is also a program which always receives client request , process the client request gives response back to clients concurrently . The basic advantage of server software is that to get concurrent access .

The following Tables gives list of server software names their vendors

  Server software Name                                      Server Vendor Name

  Tomcat                                                                Apache  Jakartha Software Foundation
  Web logic                                                            BEA Corp .
  Web sphere                                                          IBM      
  Oracle 10g                                                          Oracle Corp
  Parmathi                                                             Parmathi Software Services Hyd

Firewall : A firewall is the security program which will validate whether the client request is virus free or virus effected .

Database Software : It is used for to store the data permanently with high effective services . In industry all the data base software are known as back end technology .

Protocol  : The set of rules , used for exchanging the data between client server , application is known as protocol . In the industry all the internet applications are making use of http .

Resources Pool  : It is the place where the set of server programs are residing in the context of server Software.