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Java/J2EE and .NET
Similarities and Differences
in the Dominant Enterprise
Computing Platforms
Kyle Cordes
Oasis Digital Solutions Inc.
Gateway Java User Group
Sep. 2, 2003
Kyle Cordes
Developer / “Architect”
Consultant and Trainer
Proponent of agile, iterative, test-intensive
development
Java, EJB, Oracle, SQL Server, Delphi, C++,
Python, Ruby, EJB, XML, multi-tier, etc.
kylecordes.com
Oasis Digital Solutions Inc.
Outsourced development and other services
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Disclosures - I Like all of the
following:
Java
.NET
Choice of deployment platforms
Great development tools
Value for the customer / user
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Quick Poll - How many of you:
Use Java at work?
Use .NET at work?
Use a non-Java language on the JVM?
Deploy to Windows servers?
Deploy to Unix servers? Solaris? AIX? HPUX?
Deploy to Linux servers?
Use a non-Sun JVM, from IBM, HP, etc.?
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Agenda
Overview
Technical Similarities and Differences
Non-Technical Issues
Q&A
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
What is Java? What is J2EE?
Platform (Infrastructure under your app)
Managed runtime environment
Marketing term for a diverse set of technology
Spec and Product (from Sun and many others)
Market
J2EE is the name of the “high-end” features,
specs, libraries, etc.
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
What is .NET?
Platform (Infrastructure under your app)
Managed runtime environment
Marketing term for a diverse set of technology
Product (from Microsoft)
Spec (though less so)
Market (though less so)
There isn’t an overriding brand name for the
enterprise features, some of them are WSE
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
What Else is .NET?
Marketing term extends beyond the platform:
.NET My Services
Software as a Service
Synonym for “new”, like “NT”
Most of this is going away, Microsoft is removing
the .NET brand name from the next version of
many products, as already happened with
Windows Server 2003.
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
The Essence of .NET
Platform for building applications - like an OS
Much like Java at both macro and micro level
Microsoft’s alternative vision for what a Java-like
system should look like - “the same, but
different”
The Future of the Windows platform
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
.NET from a Java Perspective
Start with most of the best aspects of the Java
platform (both features and texture)
Same overall idea, different names and many
different design decisions
Improve on some areas, with various twists
Puts some things in platform / languages which
are conventions or add-ons in Java.
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Platforms
Java tends to make platform irrelevant
.NET integrates with and boosts the value of the
Windows platform (*)
(I’ll mention Mono later)
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Technical Similarities and Differences
Runtime Environment
Both provide a managed runtime environment:
Intermediate Language / bytecode, not native code
Garbage collection
Security
Java JRE offers JIT and Hotspot
.NET CLR offer JIT and ngen
Common misconception among .NET partisans
is that Java is interpreted
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Virtual Machine vs. Runtime
I’ve seen the idea put forth that a “runtime” is
greatly different from a virtual machine.
Technically speaking, not much difference
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Languages
 Java Platform:
 Java language
 (and many others,
though not widely used)
 .NET Platform:
 C#
 Visual Basic.NET
 C++ with Managed
Extensions
 (and many others, more
likely to see wide use)
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Major C# / Java Language
Differences
 Properties
 Attributes
 Events / Delegates
 Value Type (Structs)
 unsigned types
 Auto-boxing
 explicit interface
implementation
 Non-virtual methods by
default (like Delphi)
 Override keyword
 Different method lookup
rules
 foreach
 multi-dimensional arrays
 using
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
C# Unsafe Code
Java:
Write your unsafe code in C / C++ / etc.
Call it with JNI - VM checks security
C#:
Use the same language
Mark it as unsafe
Runtime checks security
Given that some operations require unsafe code,
writing it in the same language seems like a
better solution to me.
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Libraries
Java class libraries
 java.io
javax.sql
.NET BCL Base Class Library
System.IO
System.XML
...
Roughly comparable in scope
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Naming Conventions
Most of .NET naming/casing conventions are
different from Java’s
MethodName vs methodName
Package.Name vs package.name
Different just to be different, in my opinion
Many more things are cased LikeThis, so the
casing carries slightly less information
Microsoft no longer recommends Hungarian
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
DBMS Connectivity
 JDBC
 JDO
 SQL/J
 ADO.NET
 ODBC
 OLE-DB, which also
supports nonrelational
data sources
 JDBC Type 4
 .NET Managed Provider
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Deployment
Java:
Class files / Jars
.NET:
Assemblies
J2EE: Choose and install J2EE server, generate
and compile EJB stubs, set a bunch of XML files
right, create nested JARs, EARs, etc.
.NET: Copy assemblies and a few config files to
a directory served by IIS
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
JARs, EXEs and DLLs
.NET Assemblies are substantially similar to
JARs, but they have extra header information to
make them valid Win32 EXEs or DLLs
The header includes a stub to connect to the
.NET Runtime
Result: to the end user, .NET applications have
the same kinds of files as native.
Big advantage in user acceptance
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Classpath
Commonly complained about by Java detractors
.NET has a similar mechanism: load from the
same directory, load from a global location
(GAC), load from configured locations (much
like a classpath)
.NET does not have classes as standalone files,
which simplifies things.
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Versioning
.NET Assemblies carry metadata with version
information
.NET Assemblies reference each other by
version
Side-by-side deployment is easy, without the
need to segregate Jar files
Version interop issues are similar - it’s possible
to load class Foo version 1.5 and class Foo
version 2.0, but they aren’t the same class.
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Web Presentation Toolkits
 Java:
 JSP/Servlets
 Tab libraries
 JSF
 Third party toolkits
(Struts etc.)
 .NET:
 ASP.NET
 Server-side controls
Server-side OnClick
 Less emphasis on MVC
 Some toolkits provide
server-side OnClick just
like the .NET
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Rich Client Presentation Toolkits
 Java:
 AWT
 Swing
 “Lightweight”
 Layout management, the
bane and the glory of
Swing development
 SWT and other
alternatives available
 .NET:
 WinForms
 “Heavyweight” = Native
 Less focus on automatic
layout, most layouts are
pixel-based
 An SWT clone is available
 WinForms is “1.0” and it
shows
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
XML Support
Java: JAXP and other APIs, implementations
from many vendors
.NET: Built-in (System.XML, also including
interesting pull-model parsing)
Built-in Schema, Xpath, XSLT, SOAP 1.1
.NET uses XML itself extensively, while Java uses
lots of Properties files for older configurations;
this is an artifact of the timing.
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Distributed Computing
J2EE: RMI, CORBA, SOAP
.NET: Remoting, SOAP, DCOM
There are third party .NET COBRA
implementations.
There are third party Java DCOM bridges
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
RPCs / Distributed Objects
 RMI:
 JRMP or IIOP wire
protocol
 RMI Registry
 Stubs/Skeleton
 Can customize with
Socket Factory
 Distributed Garbage
Collection!
 .Net Remoting:
 XML or native wire
protocol, over HTTP/TCP
 Activator
 Can customize with
Channels
 Distributed Garbage
Collection!
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Web Services
RPCs, Metadata, Discovery, Directories
SOAP, WSDL, UDDI, etc.
.NET:
SOAP and WSDL in the box from Day One
More coming in the “WSE”
Java:
Some support in the box
many strong solutions from 3rd parties
Much more in the box coming soon
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
[WebMethod]
Extensively hyped, great for demos
Not an important difference in a large app
Provided by several Java WS implementations, I
was using one before .NET existed
Ludicrous to hold the fact against Java, that
Java predates web services
Upcoming versions of Java and .NET will offer
very similar WS support
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Clustering
J2EE:
Clustering provided by App Server
Sessions maintained by the App Server
Platform provides the spec
Net:
Clustering provided by OS
Sessions maintained by IIS/OS/runtime
Platform (Windows Server) provides the
implementation
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Implementing Complex Services
Service Oriented Architectures are now the
dominant paradigm
Client app doesn’t know whether server uses domain
objects
Stateless services
see Patterns of Enterprise Application
Architecture, Fowler
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
The J2EE Approach
Stateless Session Beans for the Service Facade
Entity Beans for persistance
Many variations and recommendations out there
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
The .NET Approach
Web Services or Remoting for the Service
Facade
O/R mapping is not in the box
Instead, very convenient and powerful data
access components are used
Thus, Transaction Scripting favored over Domain
Objects
Of course, many developers use O/R mapping
and domain-object-based development.
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Message Oriented Middleware
Java:
JMS and MDB specification
.NET:
Easy access to Microsoft Message Queue
COM+ Queued Components (similar to MDBs)
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Small Device Support
 Java offers J2ME
Many third party variations
also!
 J2ME is Java with many
features removed
 Run on many cell phones,
Palm devices, etc.
 Much greater market
penetration so far
 .NET offers the Compact
Framework
 .NET CF is the .NET
Framework with many
features removed
 Runs on Pocket PC,
SmartPhones, various
embedded devices
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
In Java / J2EE, not in .Net
O/R Mapping, in the form of Entity Beans
Wider array of utility APIs
Public profiling and debugging APIs like JVMPI,
JPDA
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
In .Net, not in Java / J2EE
ASP.NET Server side controls
XML Serialization
Precompilation to native code
Enumerations, Attributes, etc.
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Java / .NET Interoperability
Easy to call back and forth with Web Services
Appropriate only for large-grained EAI interaction
Much Faster to call back and forth with CORBA
Fast but inpleasant to interoperate with COM
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Mono
“an effort to create an open source
implementation of the .NET Development
Framework”
Runs on Linux
Includes runtime, compiler, partial class libraries,
various other infrastructure
http://www.go-mono.com/
Ximian, the sponsor, recently acquired by Novell
Questionable legal status given the MS patents
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Coming Soon in Java:
Generics
Auto-boxing
for() that works like foreach()
Attributes
Typesafe enums
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Coming Soon in .NET:
Generics
ObjectSpaces (transparent persistance like JDO?
XPath-like access to objects?)
Async interfaces for many more opertaions
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
The Pet Shop
This Sun example web application has been
used for a number of highly publicized
benchmarks
None of them really mean much
Overall, you’ll get similar performance with Java
and .NET
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Markets, Money, and Other NonTechnical Issues
Deployment Platforms
Java: Almost any
.NET: Any platform you want, as long as it’s
Windows
To some customers, the first point is a big
advantage; to others, the second is a big
advantage.
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Open Source
Lots of activity on both Java and .NET
Many open Java projects have been ported to
.NET.
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Jobs
Java is still apparently far ahead
St. Louis has a remarkable concentration of
large Java shops
There are many MS shops here also (and quite
a few MS, and now .NET-centric consulting
firms).
Microsoft technology very popular is small/
medium sized firms
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Market Size
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Innovation
Microsoft can advance .NET and C# forward
faster, because they have less involvement /
resistance from other companies
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Money - What’s it cost to develop?
You can develop for either for little or no money
JDK free download
.NET Framework SDK free download
Some features are not in the free downloads
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Cost Per Developer
Java can cost almost nothing per developer per
year; or it can cost several thousand dollars per
developer per year.
Microsoft offers a compelling package with
MSDN Universal
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Deployment Cost
.NET deployment is “free” if you don’t count the
OS
J2EE can be anywhere from free (Linux +
JBoss) to very expensive (HPUX, AIX +
WebLogic or WebSphere, etc.)
Unreasonable to compare the cost of .NET and
J2EE per se, since the Java cost can vary
tremendously by which app server you choose.
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
The Bottom Line
More alike than different
Technically, it’s unlikely that you will succeed
with one and fail with the other
Java is many places where .NET is not
.NET is much better integrated with Windows,
obviously the dominant platform for many
customers
Java is a broad market with many producers,
while .NET is very MS-centric.
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Talk Offer
This talk, or one like it with more details
In your organization
For Developers
For Managers
No Cost (in town)
No Obligation
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
XPSTL - Extreme Programming in
St. Louis
Interested? Join the mailing list at xpstl.org
Worthwhile even if you are only interested in
parts of XP… for example, come learn about
test-intensive development.
Tomorrow night at CAIT, see web site for
details.
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Questions?
Experiences?
Critiques?
Advice?
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
Links
http://www.daimi.au.dk/~beta/ooli/Compare.ht
ml
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes
THE END
Kyle Cordes
[email protected]
(636) 219-9589
Slides will be on my web site,
http://kylecordes.com
Copyright © 2003 Oasis Digital Solutions Inc. / Kyle Cordes