Comparing J2EE and .NET platforms layer-by-layer

Advanced Developers Conference
10.-11. Oktober 2004

Agenda
Bemerkungen
Tec 07

Motivation
Comparison
J2EE versus .NET • Overall Vision: Java and .NET
• Layer-by-Layer comparison of the infrastructures
Summary
Michael Stal
Siemens AG, Corporate Technology

Bemerkungen
Goal Some Issues

This is intended to be an objective If we are going to compare .NET and
comparisons of the two platforms Java, what do we mean?
• Will we compare Java, the language, with C#?
• Will we compare Java, the platform, with .NET, the
In will contain criteria to base a decision platform?
which platform to use • Will we compare the Java Virtual Machine with the
CLR (Common Language Runtime)?
In this talk we will try to cover most
Interoperability issues
aspects.

The Naive Approach
Bemerkungen
Layer-By-Layer Comparison Hello World Example
In C# and Java:
using System;

namespace MyNameSpace {
public class MyClass {
public static void Main(String [] args) {
Console.WriteLine(„Hello, C#!“);
}
}
}

package MyPackage;

import java.lang.*;
public class MyClass {
public static void Main(String [] args) {
System.out.println(„Hello, Java!“);
}
}

Dein Name – Dein Vortragstitel Pra 01 - S. 1

10.-11. Oktober 2004

Layers Bemerkungen is
What J2EE Technology?
• not just a set of APIs
High Level Overview
J2EE Technology Purpose
Runtime System
Object model Platform Specification Describes the minimum feature set of
J2EE APIs and standards that vendors
Base class libraries must provide
Enterprise support Reference implementation Provides a compliant and operational J2EE
platform
- Component model
- Database access J2EE Blueprints Describes how to construct J2EE
applications (including JAVA Pet Store)
- XML
- Server Pages Compatibility Testsuite Validates J2EE platform compatibility to
guarantee code portability and eliminate
- Remoting
vendor lock
- Web Services
- More Enterprise APIs

Bemerkungen
What is J2EE Technology? What is J2EE Technology?
Java-based Multi-Tier Architectures: J2EE supports
appropriate technologies for each tier

J2EE is based on J2SE, which includes the following enterprise APIs:
• Java IDL and RMI-IIOP
• JAAS (Java Authentication and Authorization Service)
• JDBC (Java Data Base Connectivity)
• JNDI (Java Naming and Directory Interface)
• JAXP (Java API for XML Parsing)

Multi-tier Architecture
Bemerkungen
J2EE „standard“ Services
Overview
Servlets
Java Server Pages
Java RMI-IIOP and RMI-JRMP
JavaIDL
JNDI (Java Naming and Directory Interface)
JMS (Java Message Service)
Java Authentication and Authorization Service (JAAS)
Enterprise JAVA Beans
JDBC (Java Data Base Connectivity)
J2EE Connector Architecture
Java Transaction API
JavaMail and JAF
Java API for XML Parsing

Of course I cannot cover them all.


10.-11. Oktober 2004

The .NET Framework Class
The Runtime System
Bemerkungen
Library
In .NET we distinguish between .NET
Framework and .NET CF
CLR
System.Web System.Windows.Forms
Services UI Design ComponentModel
Description HtmlControls Base Class Library Support
Discovery WebControls
Protocols System.Drawing Thread Support COM Marshaler
Caching Security Drawing2D Printing
Type Checker Exception Manager
Configuration SessionState Imaging Text

System.Data System.Xml
Security Engine Debug Engine
ADO SQL XSLT Serialization
Design SQLTypes XPath
IL to Native Code Garbage
Compilers Manager Collector
System
Collections IO Security Runtime
InteropServices
Configuration Net ServiceProcess Class Loader
Remoting
Diagnostics Reflection Text
Serialization
Globalization Resources Threading

Bemerkungen
Java Virtual Machine .NET Runtime
It is called the Common Language Runtime (CLR)
The JVM targets Java and interprets Java Byte Code.
It supports all languages compiled for the MSIL
Other languages can also be compiled to Java bytecode (e.g.
Provides integration for several languages
Ada)
Provides support for non-OO languages (e.g. tail
Just-in-Time compilers exist for different environments and
recursion)
OSs

C#
Compiler

Compiler

VB.NET
CLASS-
Java Classloader/
MSIL +
JIT Loader/
Files Verifier JIT
Metadata Verifier
C++‘
Garbage Garbage
Native
Interpreter Managed
Collection, Collection,
Execution
Code Perl
Security Manager Security,
Code
Call-in+Call-out, Multithreading,
Multithreading,
Hotspot ...
...

Differences and Bemerkungen
The Object Model
Commonalities
Commonalities:
• Basic infratructure is similar
Differences:
• Java is intended for interpretation (e.g. type-
dependent primitives i_add, ...)
• Java allows for custom class loaders and security
managers
• .NET is optimized for compilation and is thus
sometimes faster
• .NET CLR provides a command set that also
supports functional languages


10.-11. Oktober 2004

Object Model (Java) java.lang.Object
Bemerkungen

Java has primitive types and classes. Base of all Java classes
• No automatic boxing/unboxing public class Object {
public Object();
public boolean equals(Object obj);
Types
public final Class getClass();
public int hashCode();
Primitive Types Reference Types
public final void notify();
public final void notifyAll();
Arrays Interfaces

public String toString();
public final void wait() throws InterruptedException;
Classes
public final void wait(long timeout) throws
InterruptedException;
public final void wait(long timeout, int nanos)
throws InterruptedException;
protected Object clone() throws ClineNotSupportedException;
protected void finalize() throws Throwable;
}

Bemerkungen
Object Model (Java) Object Model (.NET)

Primitive types cannot be transparently In .NET, everything is a class
used as an object. Special Holder classes
are necessary. Types

Integer i_ref = new Integer (7); Value Types Reference Types
List l = ...
Pointers Interfaces
l.add( i_ref );
System Value User Value
Self-describing
Types Types
There are no special function references. Types

Java uses Observer Pattern with
Enumerations
Classes Arrays

callback interfaces and inner classes Delegates Boxed Values

User-Defined

Bemerkungen
System.Object Object Model (.NET)
.NET distinguishes between values types
The „mother of all .NET classes“
and reference types:
public class Object {
• value types reside on the stack
public virtual int GetHashCode();
• reference types reside on the heap
public virtual bool Equals();
public virtual String ToString();
There is no difference between primitive
public static bool Equals(object a, object b);
types and classes
public static bool ReferenceEquals(object a,
• Automatic boxing/unboxing provides transparency
object b);
public Type GetType();
Special strongly-typed function
protected object MemberWiseClone();
references
protected virtual Finalize()´;
• called delegates
}
• and events


10.-11. Oktober 2004

.NET-Types that are not .NET-Types that are not
Bemerkungen
available in Java available in Java (cont‘d)
Delegates & Events: Enumerations (value type):
class Sub { enum Color : byte { RED = 1, BLUE = 2, GREEN = 3 };
public void somebodyTurnedOnTheLight( int which ) {
Jagged (arrays of arrays) and unjagged
// do something useful
}
Arrays:
public Sub(Pub thePub) {
thePub.OnLightTurnedOn +=
new Pub.LightTurnedOn(somebodyTurnedOnTheLight); int [2][] a; a[0] = new int[]{1}; a[1] = new int[]{1,2};
} // ... int [,] a = new int[2,2];
}

Structs (value types):
class Pub {
public delegate void LightTurnedOn(int ID);
• Structs are implicitly sealed:
public event LightTurnedOn OnLightTurnedOn;
public struct not support inheritance
• they do String First;
Name {
public void SomeoneTurnsOntheLight() {
public
OnLightTurnedOn(myID);
public String Last;
} // ...
}
}

Commonalities and Bemerkungen
Metainformation
Differences
Commonalities: Java and .NET provide a reflection API
• Interfaces are „completely abstract classes“
• to load, execute, and instantiate classes
• Both support single inheritance for classes (implementation
inheritance) and multiple interface inheritance
• and inspect classes (introspection).
• Default-Initialization of variables
• Namespace-Concept (Java-Package and .NET-Namespace)
• Similar visibility attributes (public, private, ...)
In addition, .NET allows to annotate
• Generic types in .NET and Java (Generics) but .NET Generics
much more flexible and available as runtime entities
many aspects of a system (classes,
• Class constructors (static initializers in Java)
Differences: members, operations) with Attributes
• In .NET there is no difference between primitive types and
classes. Boxing to map between value and reference types.
Autoboxing now also available in Java.
• Multiple language support in .NET
• In Java all methods are implicitly virtual. In .NET this is
explicitely specified (virtual, override, new).
• Java maps packages to directories. .NET doesn‘t.

Bemerkungen
Java Example .NET Examples

Accessing and using Type information: Using an Atttribute
• Note that packages and namespaces are different [AuthorIs(„Michael“)]
issues!! class MyClass { ... }
• There are several predefined attributes
import java.lang.reflect.*;
(WebService, WebMethod, ...)
try {
Class c = Class.forName(„MyPrintComponent“);
Object o = c.newInstance();
Defining an Attribute
Method m = c.getMethod(„print“, new Class[]{ String.class });
m.invoke(o, new Object[]{„Hallo, Java!“});
[AttributeUsage(AttributeTargets.All]
}
public class AuthorIsAttribute : Attribute {
catch (Exception e) {
private string m_Name;
// handle it here
} public AuthorIsAttribute(string name) { m_Name = name;}
}


10.-11. Oktober 2004

Commonalities and
.NET Example (cont‘d) Bemerkungen
Differences
Accessing and using Type information Commonalities:
• Very similar APIs
using System;
using System.Reflection;
Differences:
namespace ComponentClient {
• .NET allows additional, user-defined meta
class Client {
information with attributes. This will also be
static void Main(string[] args) {
possible in Java using a similar approach.
Assembly a = Assembly.LoadFrom(quot;Component.dllquot;);
Type [] allTypes = a.GetTypes();
• Java Reflection is sometimes a bit more clumsy
Type t = allTypes[0];
(because of primitive types and classes)
object o = Activator.CreateInstance(t);
MethodInfo mi = t.GetMethod(quot;algorithmquot;);
• .NET allows to actually create new artifacts at
double d = (double) mi.Invoke(o, new object[]{21.0});
runtime and instantiate them or store them in
}
}
assemblies.
}

Bemerkungen
Statements Exceptions

Both platforms support basically the Exceptions in Java
same language features • Exceptions have to be declared in the throws-clause. Checked
versus unchecked exceptions
Some Differences: public int insert(int i) throws OverLimitException;
• switch-Statement allows Strings, and prevents {…}
fallthrough.
• Different iterators: foreach(et in ct) to
iterate container in .NET versus
Exceptions in .NET
for (ElementType: ContainerType) in
Java. • Exceptions are not declared
• Indexers, Operators not available in Java. // only way to tell you about
• Properties in Java are handled by coding // OverLimitException thrown below
conventions (set, get). public int insert(int i) { … }

Bemerkungen
Multithreading Multithreading in Java

In Java there is a class „Thread“ and an
interface Runnable
For synchronisation we have to use the
keyword synchronized
class GlobalData {
int m_Value;
public synchronized int setValue { return m_Value; }
}
class Worker implements Runnable {
GlobalData m_Global;
public Worker(GlobalData global) { m_Global = global; }
public void run() { m_Global.setValue(42); Thread.sleep(100); }
}
// somewhere else:
GlobalData g = new GlobalData();
Thread t = new Thread(new Worker());
t.start(); t.join(); 1


10.-11. Oktober 2004

Commonalities and
Multithreading in .NET Bemerkungen
Differences
.NET uses delegates for multithreading Commonalities:
• The „ThreadStart“ in the example below • Threading is very similar!
There are monitors for synchronization Differences:
• The “lock” in the example below • In Java, synchronization is better integrated into
the language. Different design philosophies
class GlobalData {
• Java provides better synchronization and thread
int m_Value;
communication (wait, notify, ...).
public int Value { set { lock(this) { m_Value = value; } } }
}
• In .NET it is much easier to create a thread from
class Worker {
any method. Only precondition: method with no
GlobalData m_Global;
public Worker(GlobalData global) {m_Global = global; }
result and no arguments.
public void loop() { m_global.Value = 42; Thread.Sleep(100); }
}
// somewhere else:
GlobalData g = new GlobalData();
Thread t = new Thread(new ThreadStart(new Worker().loop));
t.Start(); t.Join(); 1

Bemerkungen
Component Models Java

.jar files are similar to .NET‘s assemblies
• They can be shared or private
• They can be signed

They contain
• types
• resources
• optionally, metadata in manifest files.

There is no versioning and jar-files are
just pre-deployment-time entities!

Bemerkungen
Java Component Models Server Components in Java

Enterprise JavaBeans (EJBs) always
Client Components and Server
reside in a container that hides technical
Components
aspects (sep. of concerns)
JavaBeans are Client Components JNDI Naming

• normal Java classes following some conventions
Deployment
Service
Descriptor
1) lookup home
• optionally providing metainformation (BeanInfo EJB

class)
EJB Context
EJB
Home
2) create bean
Jar
2”) find bean
Remote Bean
Home Interface
public class MyJavaBean { new
4
Client
private int color;
EnterpriseBean
public void setColor(int v) { color = v; } ejbCreate Bean
EJB ejb...
Instance
4) remove Object
public int getColor() { return color; } bean-methods
3) Use bean Remote Bean
// a lot of more ... Interface

} EJB Run-time
Application Server (Container)

// BeanInfo class not shown here!


10.-11. Oktober 2004

Server Components in Java
OSGi
Bemerkungen
cont‘d
Additional Frameworks for small evices are available
4 Types of Beans such as OSGi, Pico, or Spring.
• Stateless Session-Beans (Service Components) OSGi Framework: a general-purpose, secure, managed
• Stateful Session Beans (Session Components) Java execution environment that supports the deployment
• Entity-Beans (Entity Components) of extensible and downloadable service applications called
bundles.
• Message-Driven Beans (asynch. Service
Components) Bundle: a software component plugged into the framework
that provides some functionality to an end-device such as a
gas meter.
An EJB bean is in theory portable across
Service: a Java object implementing a concisely defined
containers (Application Servers) from interface. Installed bundles can register a number of
different vendors. services that can be shared with other bundles under strict
control of the framework.

OSGi Architecture Bemerkungen
.NET

Component=Assembly=Set of Types
• Note that this
notion of a name Sharedname Files Types

Manifest
component is
Referenced
version Hash Security
Assemblies
Custom Product
Attributes Information

very different Type 1
Metadata
from that used
IL-Code
Type 2

with EJB or Module 1
IL-Code
Type 3
COM+ IL-Code

Resources

Bemerkungen
Server-Side Components
Component Model in .NET

Now Component is used like in EJB
Private Assemblies are typically only
useful by the owning application To use container-provided services like
Shared Assemblies are stored in a global synchronisation or transactions COM+
assembly cache and can be used by services can be used
several applications. COM+-Interop provides these features.
• They are signed by a key
• They are versioned!!
Runtime uses Application Domains as an
abstraction for isolated appartments
within a process.


10.-11. Oktober 2004

Using COM Components in
COM Callable Wrapper
Bemerkungen
.NET
For a COM.DLL it is possible to create a .NET creates a CCW for exporting .NET
RCW (Runtime Callable Wrapper). classes as COM servers:
This is a wrapper to access COM
components (with typelibs) from .NET:
COM CCW .NET
COM
.NET
Client Wrapper Component

.NET RCW COM
.NET
COM
Client Wrapper Component

Future of Distributed .NET: Bemerkungen
Indigo Architecture
Indigo
Messaging Services
Service Model
Indigo (part of Longhorn) provides common Queuing
framework for connected systems (SOA) Declarative Transacted
Instance Context Service Type
Integration Behaviors Methods
Manager Manager Methods
• Integrates Web services, .NET Remoting, MSMQ Routing

• Extensible Architecture Communication
Eventing
• Vertical functionality such as security integrated in Indigo Policy
Channels Engine
(Datagram, Reliable, Peer, …)
Service layer completely decoupled from Channel
…
Security
protocol layer. Transport Channels
Message
(IPC, HTTP, TCP…)
For more details browse to Encoder
System Services

http://msdn.microsoft.com/Longhorn/underst Transaction
Communications Manager (Port)
anding/pillars/Indigo/default.aspx
Federation
Hosting Environments
ASP.NET .container .exe NT Service DllHost …

Ports, Channels, Services,
Bemerkungen
Indigo Connectors
And Messages
A Connector is based upon 4 entities:
• Messages are in-memory envelopes (SOAP) Service

• Services are the targets of messages Port
Channel
• Ports are representations of network addresses Service
• Channels allow sending or receiving through ports Message

Applications rely on these concepts Channel

directly or indirectly
Service
Service
Channel


10.-11. Oktober 2004

Ports And Channels Port/Channel Architecture
Bemerkungen

A port is a location in network space
• Resides in a single AppDomain
Service
Service
• Has one or more affiliated transport channels
• Provides a base URI for all addresses
Messages flow through a port Port B
Port A
via channels
• Channels impose a message exchange pattern
Transport
• Channels may add additional processing code
Channels Channels

Extensions Extensions

Bemerkungen
Services And Addresses Hosting
ServiceReferences are used to identify Services can be self-hosted or activated on
message recipients demand via ASP.NET
• Absolute URI of service + fixed headers “Indigo” shares activation with ASP.NET
• Fully interoperable • Process/AppDomain Startup/Shutdown/Cycle
• ServiceAddress is relative version • Health monitoring
“Indigo” uses the IService interface to • Management
model message recipients URI namespace partitioning relies
• Maps ServiceAddress to in-memory object on metabase
• Independent of transport (HTTP, TCP, etc.)

Bemerkungen
On-Demand Activation Services In Action
Service
Client
Admin Cmd line tools Service
Mgmt APIs
MMC Plugins Service
Tools (adsutil, etc) Model Send() Receive()
Model
Proxy Session
Process
Management W3SVC
Metabase
Components

Port B
Port A
http.sys TcpListener Mail Listener IPC Listener
Listeners
Transport

Channels
Channels


10.-11. Oktober 2004

[Service] [RemoteObject]
Bemerkungen

Service-Oriented Object-Oriented
[Service] [RemoteObject]
public class Hello public class RemObj : MarshalByRefObject
Programming Model Programming Model
{ {
[ServiceMethod] public RemObj() {
Opt-In Contract Contract based on
private string Greeting(string name) Console.WriteLine(
public visibility
Schema-based
{ quot;Object {0} has been created.quot;,
return String.Format(quot;Hello, {0}!quot;, name); this.GetHashCode().ToString());
integration DLL-based integration
} }

Broad interop No Interop
public string Salutation (string name) public string Hello(string name) {
{ return
Like .NET Remoting,
return String.Format(“Howdy, {0}!”, name); String.Format(quot;Hello, {0}!”, name);
CLR-focused
} }
}
~RemObj() {
Console.WriteLine(
quot;Object {0} is being torn down.quot;,
this.GetHashCode().ToString());
}
}

Database Access in Java
Differences
Commonalities: Java provides JDBC to access relational
• Assemblies and JAR files provide „deployment“ components data
• Server Components are available (Assemblies + COM+, EJB).
Available component types in COM+ restricted
Application
• Interop with legacy components in .NET using COM+, in Java
using CORBA)
Statement
Differences:
Prepared
• EJB are a more mature and proven model Resultset Connection Driver Manager
Statement
• Special APIs in J2EE to connect to legacy systems (Java
Callable JDBC/
Connector Architecture) Statement ODBC Bridge
• Much better versioning support in .NET (side-by-side
ODBC Driver
execution)
• Future Outlook: Indigo will provide SOA container, EJB 3.0
will introuce the POJO approach to simplify development ODBC
DB

Bemerkungen
Java Example Database Access in Java

There are several other APIs:
import java.sql.*;
// without error handling:
• Embedded SQL with SQLJ (uses JDBC internally)
Class.forName(„sun.jdbc.odbc.JdbcOdbcDriver“);
• Proprietary ODBMS APIs
Connection
con=DriverManager.getConnection(„jdbc:odbc:stocks,““,““);
• Standardized JDO API to provide (more or less
Statement stmt = con.CreateStatement();
transparent) persistence for Java Objects
ResultSet rs = stmt.executeQuery(„SELECT * from stocks“);
• XML is handled differently!
while (rs.next()) {
System.out.println(rs.getString(„COMPANYNAME“));
• Java Connector API provides access to other
}
„connection oriented“ legacy systems (such as SAP
rs.close();
R3)
stmt.close();
con.close();


10.-11. Oktober 2004

Database Access in .NET ADO.NET
Bemerkungen

In .NET there is ADO.NET ADO.NET is XML based (XML Infoset)
• DataSet dnymically builds an XML schema inside to store the
• “connectionless” Client data
• Relational data and XML data can be handled in a similar
way!!
DataSet
ADO.NET works offline once the data is fetched
• Updating is partly automatic using DataSets
Command DataSetCommand DataReader
Currently there are three Managed Providers:
• SQL Server
• ADO
Connection Managed Provider
• Oracle

Data Source

XML
Differences
Commonalities:
• Decoupling of the concrete data model and the
user (using DataSets and ResultSets)
Differences:
• ADO.NET uses XML extensively, JDBC has a more
relational flavor (like ADO)
• JDBC is mainly connection oriented, ADO.NET
always works non-connected, or offline
• .NET DataSets are a kind of In-Memory-Database-
Cache.
• In Java additional O/R solutions such as JDO or
SQLJ without .NET counterpart.

Bemerkungen
XML und Java XML and .NET
There are several tools available
.NET is very XML-centric
• DOM, SAX
• Web Services (SOAP)
• Xerces/Xalan, JDOM
• JAX{M,B,R,RPC} • Configuration Files
• Castor
• Result sets of a database access (ADO.NET)
However, Java‘s libraries have not beed designed
• XML processing itself
with XML as a basis (Java‘s too old ☺)
JAXP (Java API for XML Parsing) supports DOM
and SAX).
Note that formally, many .NET features
Currently under development
are based on the XML infoset („XML
• JAXM (Java API for XML Messaging)
semantics“) and do not necessarily
• JAXB (Java API for XML Data Binding)
• JAXR (Java API for XML Registries)
require megabytes of text data!!
• JAX/RPC (Java API for XML based RPC)


10.-11. Oktober 2004

XML and .NET (cont‘d) Remoting
Bemerkungen

The System.Xml Namespace provides a
whole lot of classes
• DOM processing using XmlNode & Sons
• XPath and XslTransform
• XmlTextReader und XmlTextWriter similar to
SAX, but using a Pull-Modell (Stream-Based)
• Schema support
Two approaches: one that is closer to
the programmer‘s object model and
another one that is closer to the DOM.

Bemerkungen
Remoting in Java Some Facts about RMI

Several possibilities: RMI/CORBA/SOAP Registry tool as naming service, started
manually or automatically.
• RMI can use JRMP or IIOP as a transport protocol
On demand activation possible.
• Not easily pluggable – changes in the code are
necessary Changing lease time for DGC possible (leasing
time = time without connection).
Client Server
Usage of RMISecurityManager to allow class
loading across computer boundaries.
Stub Stub/Skeleton-Layer Skeleton
Object by value out-of-the-box.
Other protocols by imlementing proprietary
Remote Reference Manager
Socket factories.
Transport Layer

Bemerkungen
Example Example (cont‘d)

Exeptions and interface definitions Implementation of remote object:
import java.rmi.*;
// file: BoundaryException.java
import java.rmi.server.*;
public class BoundaryException extends Exception {}
// file: Grid.java public class GridImpl extends UnicastRemoteObject implements Grid {
Object[][] values; final
import java.rmi.*; static int ROWS = 20; final static int COLS = 20;
public GridImpl() throws RemoteException {
values = new Object[ROWS][COLS];
public interface Grid extends Remote { }
public void setValue(int row, int col, Object val) public boolean isOutOfBoundaries(int r, int c) {
if ((r < 0) || (r >= ROWS) || (c < 0) || (c >= COLS))
throws RemoteException, BoundaryException; return true;
public Object getValue(int row, int col) else return false;
}
throws RemoteException, BoundaryException;
public Object getValue(int row, int col)
public int getColumns() throws RemoteException, BoundaryException {
throws RemoteException; if (isOutOfBoundaries(row, col)) throw new BoundaryException();
else return values[row][col];
public int getRows() }
throws RemoteException; ...
}
}


10.-11. Oktober 2004

Example (cont‘d) Example (cont‘d)
Bemerkungen

The Server Main Client
import java.rmi.*;
import java.rmi.registry.*;
import java.rmi.*;
import java.rmi.server.*;
public class GridClient {
public static void main(String args[]) {
public class GridServer { try {
Grid g = (Grid)Naming.lookup(quot;gridquot;);
public static void main(String args[]) throws g.setValue(4,4, new Integer(42));
Exception { Integer i = (Integer) g.getValue(4,4);
System.out.println(i);
GridImpl svr = new GridImpl();
g.setValue(33,33, new Integer(88));
Naming.rebind(quot;gridquot;, svr); }
System.out.println(quot;readyquot;); catch (BoundaryException b) {
System.out.println(quot;Boundary violationquot;);
} }
} catch (Exception e) {
System.out.println(e);
}
}

}

Bemerkungen
Remoting in .NET Remoting in .NET (cont‘d)
.NET Remoting provides pluggable
transports and formatters
Application Domain A Application Domain B
• currently TCP and HTTP transport and
• binary and SOAP formatters
Client Servant
Contexts are automatically propagated
(very neat feature!!)
Only very simple lifecycle management
Transparent Proxy
Object Context Sinks

options for servants (compared to EJB or
Real Proxy
Server Context Sinks
Envoy Sinks
CORBA)
Channels
Channels Network
• Singleton (one object for all calls)
Formatters Formatters

• SingleCall (new instance for each call)
• Client-Activated based on leases

Web
Differences
Commonalities:
• Relatively easy to use
Differences:
• .NET Remoting can be extended more flexibly
• Java provides interoperability with CORBA
• Asynchronous invocations not directly supported
by Java
• No activation mechanism provided in .NET
Remoting


10.-11. Oktober 2004

Java Server Pages and
Java Example
Bemerkungen
Servlets
Java allows for server-side scripting
• JSPs are based on Servlets
Other
(1) get a.jsp (2) process
Components
Web JSP
Client
Server
(5) HTTP file
(3) gen. Servlet Servlet
Impl.
(4) result
Servlet
Database

JVM

Complementary Technologies
Bemerkungen
Java Example in Java
Bean and JSP: Servlets are server-side extensions providing
functionality. Implemented by Servlet Engine.
// Datei MyPerson.java
JSPs (Java Server Pages) are scripted Web
package MyPackage;
pages transformed to servlets.
import java.lang.*;

Taglibs allow to integrate additional html/xml-
public class MyPerson {
ike tags.
public String getFirstName() { return quot;Michaelquot;; }
public String getLastName() { return quot;Stalquot;; }
Java ServerFaces use taglibs to provide Web
}
components.
// Datei MyTest.jsp:
<HTML> <BODY>
Apache Struts provides a framework for
<jsp:useBean id=quot;personquot; scope=quot;sessionquot;
implementing MVC applications.
class=quot;MyPackage.MyPersonquot;/>
Your name is: <br>
<jsp:getProperty name=quot;personquot; property=quot;firstNamequot;/> <br>
<jsp:getProperty name=quot;personquot; property=quot;lastNamequot;/>
</BODY> </HTML>

ASP.NET Bemerkungen
ASP.NET Example
(Server-Side Scripting)
ASP.NET Architecture: A simple login
screen:
Other
IIS 5
(1) get a.apx (2) process .NET Assemblies
Web
Client Assembly
Server
(4) HTTP file

.NET
Engine
(3) result

Database


10.-11. Oktober 2004

ASP.NET Example (cont‘d) ASP.NET Example (cont‘d)
Bemerkungen
<%@ Page language=quot;c#quot; Codebehind=quot;WebForm1.aspx.csquot; // lot of details omitted
AutoEventWireup=quot;falsequot; Inherits=quot;LoginPage.WebForm1quot; %> namespace LoginPage {
<!DOCTYPE HTML PUBLIC quot;-//W3C//DTD HTML 4.0 Transitional//ENquot; > public class WebForm1 : System.Web.UI.Page {
<HTML> protected TextBox PasswordText, LoginText;
<body> protected Button EnterButton;
<form id=quot;Form1quot; method=quot;postquot; runat=quot;serverquot;> protected Label MessageLabel;
<asp:Label id=quot;TitleLabelquot; runat=quot;serverquot;>Please specify your name and private void InitializeComponent() {
password</asp:Label> <br> this.EnterButton.Click +=
<asp:Label id=quot;LoginLabelquot; runat=quot;serverquot;>Login</asp:Label> <br> new System.EventHandler(this.EnterButton_Click);
<asp:TextBox id=quot;LoginTextquot; runat=quot;serverquot;></asp:TextBox> this.Load += new System.EventHandler(this.Page_Load);
<asp:RequiredFieldValidator id=quot;RequiredFieldValidatorquot; runat=quot;serverquot; }
ErrorMessage=quot;You need to specify your namequot; private void EnterButton_Click(object sender, System.EventArgs e) {
ControlToValidate=quot;LoginTextquot;></asp:RequiredFieldValidator> <br> if (!(LoginText.Text.Equals(quot;aladdinquot;) &&
<asp:Label id=quot;PasswordLabelquot; runat=quot;serverquot;>Password</asp:Label> <br> PasswordText.Text.Equals(quot;sesamquot;))) {
<asp:TextBox id=quot;PasswordTextquot; runat=quot;serverquot; MessageLabel.Text = quot; Wrong name or password!quot;;
TextMode=quot;Passwordquot;></asp:TextBox> <br> }
<asp:Button id=quot;EnterButtonquot; runat=quot;serverquot; Text=quot;Open the entrancequot; else {
ToolTip=quot;Press this after you have specified login and Session[quot;userquot;] = quot;aladdinquot;;
passwordquot;></asp:Button> <br> Response.Redirect(quot;UserArea.aspxquot;);
<asp:Label id=quot;MessageTextquot; runat=quot;serverquot;></asp:Label> }
</form> }
</body> }
</HTML> }

XML Web Services
Differences
Commonalities:
• Pages are precompiled to accelerate access
• Similar syntax and concepts
• ASP.NET provides „GUI components“ using
Webcontrols, Java provides Taglibs.
.. why today‘s Web does not solve all the
Differences: problems.
• All .NET languages can be used for ASP.NET
scripting
• Servlets/JSP are available for a wide range of
webservers
• Many open source implementations, frameworks
and tools for Java

Why do we care about Service-Oriented Bemerkungen
Services
Architectures and Web Services

What is a service?
Cannot take single-vendor approach to IT • A remotely accessible self-contained piece of coarse-grained
(because of risk, pricing, etc.) software functionality with at least one unique physical address to
which a service consumer can bind using a communication
• Embracing heterogeneity protocol supported.
• A service exports functionality using standardized service
Interoperability is the only viable and interfaces. There might be multiple service interfaces denoting
economic approach different types of business functionality or different types of
communication protocols.
Accelerating change in IT due to globalization, • Services are implementation agnostic in that the implementation
technology used (container, programming language, middleware,
e-business, etc. underlying server infrastructure) is not made visible.
• Services are singletons. In contrast to CORBA, DCOM, RMI there
Service-Oriented Architectures/Web Services are no instances.
have ubiquitous support of all major vendors • Services are defined using a high level description language
(XML)
Standardization


Comparing J2EE and .NET platforms layer-by-layer

Comparing J2EE and .NET platforms layer-by-layer

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