Lets have  a look at an analogy between Microsoft and Sun Technologies.

Considering a sample 3 tier architecture, here is a comparison for the technological components used in J2EE and .NET applications.

 

 
J2EE
.NET
Presentation Tier
User Interface
Java Server Pages (JSP) - .jsp
 ASP.Net ( xxxx.aspx pages)
Client Side scripting for UI validations
Java Script - .js
 JavaScript
Central Request Controller
Java Servlet - .java
 HttpHandler class (written in C# or VB.net)
Specific Request Handler/Processor
Action Class - .java
 Code Behind Class (one for each ASPX pages)
 
 
 
Business Tier
Middle tier controller
Session EJBS (Java Classes) - .jar
 Web Service/WCF Service/ Microsoft Enterprise Services (COM+)
Business Component
Pure Java Class/s - .java or .jar
 Component written in C# or VB.net
 
 
 
Data Access Tier
 
Pure Java Classes - .java
Component written in C# or VB.net

 

 
J2EE
.NET
Web Server
 
Apache Web Server/ Tomcat
IIS 5, IIS 6
 
 
 
Application Server
 
JBoss AS/Weblogic/Websphere
NA
 
 
 
Database Server
 
Oracle/SQL/DB2
 SQL Server 2005
 
 
 
Messaging Platform
 
MQ Series
MSMQ 3.0 or 4.0