Java vs .net

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JAVA & .NET (BC vs. IL)

Microsoft .NET Framework Vs. Java

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 The Common Language Infrastructure CLI and Microsoft
.NET Framework languages like C# and VB share
various similarities with Sun Microsystems’s JVM and
Java.
 These are virtual machine models which conceal the
computer hardware details on which their programs run.
The other similarity is that both of these frameworks
make use of their own intermediate byte-code.
 Microsoft naming theirs Common Intermediate
Language and Sun naming theirs as Java bytecode.

Java and C#.NET
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hello.java hello.cs

javac csc

hello.class hello.exe
9E8E 9E8E
Java bytecode Common Intermediate
Language (CIL)

> java hello > hello.exe assembly

these run in different
virtual machines

Common Intermediate Language

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 Common Intermediate Language formerly called MSIL is
the lowest-level human-readable programming
language defined by the Common Language
Infrastructure (CLI) specification and is used by the .NET
Framework and Mono.
 Languages which target a CLI-compatible runtime
environment compile to CIL, which is assembled into
an object code that has a bytecode-style format.
 CIL is an object-oriented assembly language, and is
entirely stack-based. Its bytecode is translated
into native code or executed by a virtual machine.

Bytecode
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 Bytecode, also known as p-code (portable code), is a
form of instruction set designed for efficient execution by
a software interpreter.

 Bytecodes are compact numeric codes, constants, and
references which encode the result of parsing
and semantic analysis of things like type, scope, and
nesting depths of program objects.

 They therefore allow much better performance than
direct interpretation of source code.

Java Byte Code and MSIL

 Java byte code (or JVML) is the low-level languageG53ELC
of the
JVM.

 MSIL (or CIL or IL) is the low-level language of the .NET
Common Language Runtime (CLR).

 Superficially, the two languages look very similar.
MSIL:
JVML:
iload 1 ldloc.1
iload 2 ldloc.2
iadd add
istore 3 stloc.3

Cont..

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 One difference is that MSIL is designed only for JIT
compilation.

 The generic add instruction would require an interpreter
to track the data type of the top of stack element, which
would be prohibitively expensive.

Bytecode & MSIL contains…
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 Load and store

 Arithmetic and logic

 Type conversion

 Object creation and manipulation

 Operand stack management

 Control transfer

 Method invocation and return

The execution engines
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 The Bytecode and MSIL is interpreted by virtual
machines…

 JVM for Java Bytecode

 CLR for MSIL

Java virtual machine (JVM)
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 A Java virtual machine is
software that is
implemented on virtual
and non-virtual
hardware and on
standard operating
systems.
 A JVM provides an
environment in which
Java bytecode can be
executed, enabling such
features as automated
exception handling,

Java Run-Time System
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Just-in-
time
Compiler
Byte
Class Hardware
Code
Loader
Verifier
Java
Interpreter
Runtime

JVM Architecture
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A Bytecode Example
public class X { public static void G53ELC
main(java.lang.String[]);
public static void Code:
main(String[] args) { 0: iconst_1
add(1, 2); 1: iconst_2
} //Method add:(II)I
2: invokestatic #2; 5: pop
public static int 6: return
add(int a, int b) {
return a+b; public static int add(int,int);
} Code:
} 0: iload_0
1: iload_1
2: iadd
3: ireturn

Common Language Runtime
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 CLR sits on top of OS to provide a virtual environment for
hosting managed applications

 What is CLR similar to in Java?

 Java Virtual Machine (JVM)

 CLR loads modules containing executable and executes
their code

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 Code might be managed or unmanaged

 In either case the CLR determines what to do with it

 Managed Code consists of instructions written in a
pseudo-machine language called common intermediate
language, or IL.

 IL instructions are just-in-time (JIT) compiled into native
machine code at run time

Compiling and executing
managed code
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Compilation Microsoft
Source Language Intermediate
Code Compiler Language
(MSIL)

The first time each
method is called

Native JIT
Code Compiler

Execution

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Programming model
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CIL &
Source Compiler Metadata
Code

Common Language Runtime Class
Class Loader
Execution Engine Lib

JIT Compiler

Managed
Execution native
Code

C# Code
 using System; G53ELC
namespace Swapping
{
class Swap
{
int a, b, c;
public void Get()
{
Console.WriteLine("Enter 2 no");
this.a = Convert.ToInt32(Console.ReadLine());
this.b = Convert.ToInt32(Console.ReadLine());
}
public void Show()
{
this.c = this.a;
this.a = this.b;
this.b = this.c;
Console.WriteLine("After Swapping a={0} b={1}", this.a, this.b);
}
}
}

CLR vs JVM
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VB Managed Lots of other
C# .Net C/C++ Languages Java
MSIL Byte Codes

CLR JRE (JVM)
CTS GC Security GC Security
Runtime Services Runtime Services

Windows OS Mac Win Unix Linux

Both are „middle layers‟ between an intermediate
language & the underlying OS

25

JVM vs. CLR
 JVM designed for platform independence G53ELC

 Single language: Java (?)

 A separate JVM for each OS & device

 CLR designed for language independence

 Multiple languages for development

 C++, VB, C#, (J#)

 APL, COBOL, Eiffel, Forth, Fortran, Haskel,
SML, Mercury, Mondrian, Oberon, Pascal, Perl,
Python, RPG, Scheme, SmallScript, …
26

G53ELC
 Impressive usage of formal methods and
programming language research during
development

 Impressive extensions for generics and support
for functional languages underway

 Underlying OS: Windows (?)

JVM vs. CLR at a glance
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JVM CLR
Managed execution X X
environment
Garbage Collection X X
Metadata and Byte code X X
Platform-abstraction class X X
library
Runtime-level security X X
Runs across hardware X ?
platforms
28

A typical .NET
Enterprise Solution
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IIS on W2k Server

Browser .NET SQL
ASP managed Server
.NET component

Windows
Client

29

A typical J2EE
Enterprise Solution
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Java App
Server DB
Browser
Servlet Server
EJB
JSP

Java
Client

30

Web services
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 Web services are typically application programming
interfaces (API) or Web APIs that are accessed via
Hypertext Transfer Protocol (HTTP) and executed on a
remote system hosting the requested services.

 An application that exists in a distributed environment,
such as the Internet.

 A Web service accepts a request, performs its function
based on the request, and returns a response.

Advantages of Web service
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 Not based on a programming language:
Java, .Net, C, C++, Python, Perl, …

 Not based on a programming data model:
objects vs non-objects environments.

 Based on web technologies

 Do not need huge framework of memory.

 Basic usage is b-to-b ,remote controlled devices ,etc.

Web services application
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Can use Web Services to integrate across departments,
agencies, to companies, etc.

Web service Architecture
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An architecture view based on SOAP, WSDL, and UDDI.

WS built on existing standards
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 Extensible Markup Language (XML)
 The HTTP (Hypertext Transfer Protocol) standard is
allowing more systems to communicate with one
another.
 SOAP (Simple Object Access Protocol) (built on XML)
standardizes the messaging capability on different
systems.
 UDDI (Universal Description,Discovery, and Integration )
standardizes the publishing and finding of Web services.
 WSDL (Web Services Description Language )
standardizes the description of Web services so providers
and requesters are speaking the same language.

Web Services technology
3 major Web services toolkits being used widely, G53ELC
 .NET Web services: Developed by Microsoft and is an
integral part of the complete .NET framework. Integrated
and easy to use with Visual Studio .NET. services are hosted
on IIS web servers.

 Java Web services: Sun’s Web service implementation for
the Java community. Comes bundled in a complete Java
Web services Development Pack (JWSDP Ver 1.3) including
Tomcat web server.

 Apache Axis: Initially developed by IBM and donated to
the Apache group. One of the earliest and stable Web
service implementation. Runs on Apache Web servers.

A Web Service example in Java
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HTTP Server

Servlet engine (e.g. Apache Tomcat)

Any class
Any class
processing
Any class
processing
Any class
the incoming
processing
the incoming
processing SOAP-aware Sending
requests
the incoming
requests requests,
(“businessincoming
the logic”
requests
Servlet
(“business logic”
requests (e.g. Apache Axis) getting
(“business logic”
(“business logic” results

Usual principles of Java toolkits

 Writing server is easier than writing clients (butG53ELC
only
regarding the toolkit, not the business logic)

 Servers may be written independently on the used
toolkit

 Always test interoperability with a non-Java client
(because of data serialization and de-serialization)

 Steps:
 write your service implementation

 make all your classes available to the toolkit

 deploy your service (usually done just once)

 restart the whole servlet engine

 test it with a client request

hello/HelloWorld.java
package hello; G53ELC
public interface HelloWorld {
String getHelloMessage();
void setHelloMessage (String newHello);
}

hello/HelloWorldService.java
package hello;
public class HelloWorldService
implements HelloWorld {
String message = "Hello, world!";
public String getHelloMessage() {
return message;
}
public void setHelloMessage (String newMessage) {
message = newMessage;
}
}

import org.apache.axis.client.*;
HelloWorldClient.java
public class HelloWorldClient {
public static void main (String [] args) {
try { G53ELC
// prepare the call (the same for all called methods)
Call call = (Call) new Service().createCall();
call.setTargetEndpointAddress
(new java.net.URL("http://localhost:8080/axis/services/Hello"));

// call "get message"
if (args.length == 0) {
call.setOperationName ("getHelloMessage");
String result = (String) call.invoke ( new Object [] {} );
System.out.println (result);
System.exit (0);
}

// call "set message" and afterwards "get message"
call.setMaintainSession (true); // TRY also without this line...
call.setOperationName ("setHelloMessage");
call.invoke ( new Object [] { args[0] } );
call.setOperationName ("getHelloMessage");
System.out.println (call.invoke ( new Object [] {} ));

} catch (Exception e) {
System.err.println ("ERROR:n" + e.toString());
}
}

Generated for HelloWorld
1. Make an instance of this G53ELC
HelloWorldService
implements
2. Use it to make an instance of this

HelloWorldServiceLocator

getHello()

HelloWorld
3. Call methods on this proxy object
implements

HelloSoapBindingStub

HelloWorldClientFromStubs.java
public class HelloWorldClientFromStubs { G53ELC
public static void main (String [] args) {
try {
// prepare the calls (the same for all called methods)
hello.generated.HelloWorldService service =
new hello.generated.HelloWorldServiceLocator();
hello.generated.HelloWorld myHelloProxy = service.getHello();

// call "get message"
if (args.length == 0) {
String result = myHelloProxy.getHelloMessage()
System.out.println (result);
System.exit (0);
}

// call "set message" and afterwards "get message”
myHelloProxy.setHelloMessage (args[0]);
System.out.println (myHelloProxy.getHelloMessage());

} catch (Exception e) {
System.err.println ("ERROR:n" + e.toString());
}
}
}

Java vs .Net Solutions
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 Both multi-tiered, similar computing technologies

 Both support “standards”

 Both offer different tools & ways to achieve the same
goal.

 A lot of parallelism can be seen.

43

.NET vs. Java:
standard libraries
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 .NET Framework class library
 Defined by Microsoft
 Somewhat Windows-oriented
 Organized into a hierarchy of namespaces

 J2SE, J2EE
 Defined by Sun and the Java Community Process
 Not bound to any operating system
 Defined as packages and interfaces

Class Libraries
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The TMC Petshop
Performance Case Study
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 Java Pet Store is Sun’s primary blueprint application for
J2EE

 Source: http://java.sun.com/j2ee/blueprints

 Illustrates best coding practices for J2EE

 Ships as a sample application in IBM Websphere,
Oracle Application Server 9i, Sun iPlanet, and
BEA WebLogic

47

 The .NET Petshop is a port of the J2EE Java Pet Store to
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.NET
 Source: http://www.gotdotnet.com/compare
 Implements the same functionality as Java Pet
Store
 Illustrates best coding practices for .NET
Framework

 In the TMC Petshop Performance Case Study, The
Middleware Company implemented both the Java Pet
Store and the .Net Petshop.
 The J2EE version ran on two different application
servers
 All versions used the same hardware and OS

Java Pet Store Components
 The Storefront presents the main user interfaceG53ELC
in a
Web front-end. Customers use the Storefront to place
orders for pets.

 The Order Processing Center (OPC) receives orders
from the Storefront.

 The Supplier fulfills orders from the OPC from
inventory and invoices the OPC.

 The Admin presents the administrator interface in a
JFC/Swing front-end. Administrators use the Admin to
examine pending orders and approve or deny them.

49

Java Pet Store vs. .Net Pet Shop
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50

Porting Java Pet Store to .NET
15500
14,273 Lines of Code Required G53ELC
14000

.NET Petshop
11500
Java Pet Store
9000

7500
5,891 5,404
4,410
5000
2,865 2,566
2500 710 761 412 74

Total Lines User Middle Tier Data Tier Configuration
of Code Interface
51

TMC Pages per Second
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52

TMC Max Supported Users
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53

A Comparison .NET or J2EE?
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 Which is best?
 In what way?
 For what purpose?
 Performance
 Cost
 Developer time

Application Platforms Today
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Browser Web Services Local Other
Apps Apps Apps Apps

GUI Transaction Web Data More
Services Services Scripting Access
Standard Library

Runtime Environment

Operating System

The .NET Framework
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Apps Apps Apps Apps

Windows Enterprise ASP.NET ADO.NET More
Forms Services
.NET Framework Class Library


Windows

The Competition-
The Java Environment
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Apps Apps Apps Apps

Swing Enterprise JavaServer JDBC More
JavaBeans Pages
Standard Java Packages

Java Virtual Machine (VM)

Windows, Solaris, Linux, others

But!
 .NET IS COMPELLING! G53ELC

 It has everything an enterprise architecture needs
 It is fast
 It is simpler to use than J2EE to develop
 It has features that J2EE does not –
 eg web forms
 It is ahead of the game in my opinion

.Net Needs Less Code
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Runtime Statistics
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 .NET ran 28 times faster that J2EE
 Supported 7.6 times more concurrent users
 Used ¼ the CPU cycles for the same load
 Do not believe these statistics!
 Picked to show MS in best possible light
 But it .NET is probably more efficient

Reference
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 Unix Internal- Urash Vahalia
 Operating Systems-William Stallings

Java vs .net

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