C and C++.
why java is important
for internet?
Java has
evolved to be the most popular general purpose programming language of the
current age. Java plays a significant role in the corporate world. Companies of
all sizes are using Java as the main programming language to develop various
applications/projects worldwide. It has found its use in various sectors
including banking, insurance, retail, media, education, manufacturing and so
on. E-commerce, Gaming, Mobile, Embedded, Media and
many more types of applications are being developed using Java.
Why
java is suitable for internet is, because of two reasons. 1. It is system
independent and hence its programs can run on any type of computer system
available on internet.
2. It eliminates a lot of security problems for data on
internet.
Let us discuss the above points.
Suppose if we are writing a C program with name Demo.c , as per our requirement. When we compile
this program , we get Demo.obj file that contains machine language code and
that file contains first statement to include a header file like
<stdio.h>.when we run the program, C complier to the
C standard library and searches for the header file <stdio.h>
there. When it found, C compiler copies the entire code from the header file
into Demp.c program. So if we write a C
program of 10 lines and the <stdio.h> file contains 100 lines, then the
total size of the file will be 110 lines. This file is called Demo.exe file.
This file contains machine language instruction which are understandable to the
microprocessor. So it execute them and gives the results.
 Demo.c |
Demo.exe
|
|
output
|
Demo.obj
|
The above diagram represents execution of c
program.
we have many operating systems like Dos, linux,
unix…etc and every operating system
stores the data and instructions in different formats. So if we created an .exe
file in C or C++ on X processor and Y Operating system, then we execute it on X
processor and Y operating System only.
If the processor or operating system is changed, then it is not possible to execute the same code. They cannot be
executed on a different configuration. So they are called system dependent
languages.
As we know that internet is
a global network of all the computers existing on the earth and anyone can
connect his/her computer to internet. So there will be different types of
computers with different configuration. So if we develop a software in c or c++
like languages, that software can be
distributed on the internet and people can download the .exe files, but they
cannot run those files because of their system dependence. So c/c++ are not
suitable to develop software for internet.
In java ,if we write a program, it is stored with an
extension .java. let us say x.java. it contains source code statements. If we
compile that program, java compiler first translate the x.java into x.class
file. And this file contains byte code
instructions.
But the microprocessor cannot understand the byte code
instructions. In java we hava JVM(java virtual machine), it can understand the
byte code instructions and covert them into machine code. We will discuss about
JVM in next class.
|
x.java |
|
JVM
|
|
output
|
|
x.class
|
Java program
byte code
jvm converts byte code into machine code
JVM understands the operating system in the computer and
accordingly it forms the instructions. So there will not be any problem for the
operating system with a different processor.
So if we created an .java program on X processor and Y
Operating system, then that program is executable on any other computer system
with any processor and operating System . this means
java programs are system independent.
On internet , different computer systems with different
processors and different operating systems are available, but still java
programs will run any system and produce the same results on all the systems.
If we developed a software in java language, the .class
files are downloaded from internet and
can be executed on any other system without any problem. Hence java is
suitable for internet.
Q: what is the difference between .exe and .class file?
A: .exe file
contains machine language instructions for the microprocessor and is system
dependent. .class file contains byte code instructions for the jvm and is
system independent.
Internet is public network, everyone can connect their
computers into internet and this leads to several security problems. For
example if we are sending a message to a
friend. Now this message will go through millions of servers on internet before
reaching the destination computer. In between anybody can see the data of the
message. Let us discuss some major security problems for data on internet.
hacking : means stole the others data without their
permission.
Eavesdropping: means
reading others data illegally on internet. For example opening others emails
and reading them. The solution for this problem is encryption and decryption.
Converting data into and unreadable format is call encryption and getting back
the original data from the encrypted format is call decryption. Encryption and decryption can be done by java
technology.
Impersanation: means
a person acting himself as
another person on internet. Many people hide their original identity and act as somebody else to make
transactions. The solution for this problem is digital signature. Digital
signature is a file that contains personal identification information in an
encrypted format. It can be created using java tech.
Tampering: means not only reading other data but also
modifying . encryption and decryption is the solution for this problem.
Virus: it
represents a program that can cause harm
to the data, software and hardware of system. Most of the viruses spread with
.exe ,.doc,images , audio and videos files. Viresus cannot spread with .txt
file. In java .class file, which are similar to
.txt files and there is no chance of virus affecting these files.
From the above problems , we can say that java can eliminate the above security problems
that often occur on internet.
No comments:
Post a Comment