C# & .NET Expert Christian Nagel
|This week, Stephen Ibaraki, I.S.P.,
has an exclusive interview with Christian Nagel.
Christian is a highly respected authority on C#, and
application development and author of, “Beginning
C#” which is intended for beginners or relatively
inexperienced programmers, e.g. programmers who
write scripts for ASP development. This book
explains the basic of C# programming and gives an
in-depth look into object oriented programming plus
discusses the basics of Windows programming, dynamic
web pages, and web services. He has co-authored two
additional books: “Professional C# Web Services” and
“Data Centric .NET Programming with C#.”
Professional C# Web Services covers both ASP.NET Web
Services as well as .NET Remoting. Data Centric .NET
Programming with C# provides information to create
data-centric applications and covers ADO.NET, XML,
Active Directory, Messaging Services, etc. As a
reviewer, Stephen finds all of Christian’s books of
the highest quality. Stephen conducted this
interview with Christian who resides in Austria and
works in Curriculum Management Software Development
for Global Knowledge and as MSDN Regional Director
Q: First of all, thank you Christian for agreeing to
this interview. What does your family think about
your career as a noted author?
A: My wife fully supports all my activities. We both
are workaholics and our motto is “full speed ahead”.
Q: For your latest book on C# and .NET development,
you were on tight deadline. Please expand on the
topics you were forced to delay?
A: There was a tight deadline, but it didn’t
influence the topics covered in the book. Beginning
C# has all chapters useful for a beginner doing
software development with C# and the .NET Framework.
We not only cover the syntax of C# and an
introduction to object oriented programming, but
also major topics of the .NET framework like
creating rich client applications, database access,
Web services, and so on.
Of course I had to reduce and to delay some of my
other activities, e.g. I reduced the time that I
spent for Kart racing to a large extent.
Q: Christian, can you expand on how .NET is so
different: a new way to build distributed desktop
applications; a new way to produce mobile
applications; very different from classic COM (no
class factory, doesn’t use IUknown, no registration
in the registry)?
A: All what you say is correct: .NET is a new way to
build distributed applications, desktop
applications, mobile applications, and it is very
different from classic COM. But the major issue with
.NET is that the time required to program
applications can be reduced. Today it is very
important to get solutions fast to the market, if
the development cycle takes too long, the product is
already old and cannot be sold anymore.
We have to reduce the time dealing with technology
issues and focusing on the solution. .NET helps a
lot with these issues; no matter if desktop,
distributed, mobile, Web, etc applications are to be
Q: What is C#?
A: C# is a new component-oriented programming
language that was designed for the .NET Framework.
There are many similarities with C++ and Java, but
there are also many new ideas added that help with
Q: What are your tips for learning the types defined
in the .NET base class libraries since this is the
heart of .NET and not necessarily learning the
syntax of C# or other supported languages?
A: First the syntax of C# or any other programming
language and concepts of object orientation must be
learned before going into the .NET base class
libraries. The chapters of the book Beginning C# are
very well ordered in so far that the reader learns
about the C# syntax, gets grips with object
orientation, and digs into the classes of the .NET
framework. Not only reading the book, but also doing
the exercises that complete every chapter helps a
lot learning the class libraries. Besides reading
the book, the courses at Global Knowledge lead to a
profound understanding of .NET.
Q: Your experiences as a respected and widely known
guru would be of benefit to many veterans. Can you
detail your personal history and how you came to
write? What personally prompted you to enter the
computing field? What led you to becoming a note
expert on application development?
A: Now I have been working with different systems
like PDP11, VMS, Unix, Windows, different
technologies like X-Windows, Motif, DCE, DCOM, MTS,
… for many years. Before writing books I have
created special courses for Global Knowledge, and I
was a reviewer for a lot of ATL / COM titles at Wrox
Q: Can you share your 20 leading tips for those
thinking of getting into the computing field? Can
you describe your role with your company and how you
plan to shape the company one year and two years
into the future, and in the long term?
A: I don’t have 20 tips, but here are a few I regard
as really important:
The most important tip is that it is awfully
necessary to have an irresistible urge for diving
into the computing field. If you want to be
successful, don’t ever think about a 40 hours job.
In this field you have to be open-minded for new
things which include continuous learning.
Be aware of your talents. There is an immense broad
spectrum of talents needed in the computing field.
Graphical talents are required for the user
interface design for both Web and Windows
applications, interaction with customers, writing
talents, mathematically thinking… You shouldn’t be
afraid of trying something out; from the beginning
it is often not clear what your talents really are.
At Global Knowledge I’m trainer and Curriculum
Manager for the software development business in
Central Europe. Global Knowledge is the world’s
largest independent IT training and certification
company offering more than 700 courses in more than
60 international locations. Every year, Global
Knowledge trains more than 300.000 IT professionals
on the leading edge technologies which their
companies need to stay competitive. In Austria we
are very successful in teaching software
development; during the last years we succeeded in
growing this business line dramatically. For the
next years I plan to extend this success to Germany
and Switzerland as well.
Q: You have a reputation for being plugged into the
stream of computing consciousness about where it’s
going now and in the long term. You’ve also done a
lot of research. Can you comment on the studies that
you’ve performed, what you have learned, and your
experiences? Where is technology today and where is
A: I am happy that I started development on the
PDP11 system where I created assembler programs to
test devices. That way I’ve learned how a system
really works. Later I’ve created applications on VMS
and UNIX systems, before I turned to Microsoft
technologies. Here I used C++, OLE, COM, COM+, etc
before I learned .NET in the summer of 2000.
Looking back to that way, the applications that are
developed become more and more complex. This is only
possible by adding abstractions so that the focus
can be put more and more on the solution instead of
the technology. One abstraction was done with
virtual memory and threads. Managed code adds
another important layer where the runtime deals with
a lot of issues that we had to deal before. These
abstractions make it possible to create more complex
applications in a shorter time.
Q: Can you comment on the integration of mainframe,
Unix, and Windows-based technologies and how they
all fit in large, complex, enterprise environments?
A: Let’s set a step backward. We have CORBA, DCOM,
and EJB for object communication. CORBA from the OMG
has the problem that different implementations
couldn’t be well integrated even if they were
running on the same platform. Microsoft founded the
Active Group that built DCOM not only for Windows,
but also for UNIX hosts and mainframes. But don’t
expect a mainframe administrator to install some
Microsoft technology on the host. Sun has EJB where
Java is a requirement. All these technologies have
their market place, but we cannot expect that one of
these technologies will get 100% market share and
all the others disappear.
With XML Web Services we have a way to integrate
these different technologies. The SOAP protocol used
by XML Web Services is a standard initiated by
Microsoft where many different vendors – including
Sun - agreed to. XML Web Services is the way to go
to integrate different platforms.
Q: What are your views on top four programming
environments and their future?
A: Instead of programming environments I want to put
my focus on languages.
As for me C++ will not be that important as it is
today. It will still be used to create device
drivers, but the importance for creating business
solutions will drop. Java still has the advantage of
being platform independent. .NET still needs some
time to meet such a requirement. For development on
Windows systems, .NET already has a lot of
advantages and is the way to go. I don’t think that
C# will be the only important language on this
platform. Visual Basic is used by a lot of
programmers nowadays. Working with .NET they have to
learn many new things. For example Visual Basic 6
didn’t support full object oriented programming,
this is now possible with Visual Basic .NET. In the
future I’m convinced that .NET programming will be
made easier for Visual Basic .NET programmers with
some designer extensions and design time controls. I
believe that C# will be the major language on this
new platform. It is not only newly designed to have
an extremely good fit for .NET, it is also made
available as a standard (see http://www.ecma.ch). C#
will not only be available for Windows systems, but
for other platforms as well. Therefore C# will be
the most important language in the future. All other
languages I didn’t talk about will not play a major
Q: What are your views on XML and its future?
A: XML is an important technology that laid the
foundation for most of the new technologies we see
today. A lot of standards based on XML that are
necessary for the rich business applications still
must be defined, e.g. the Global XML Web Services
Architecture (GXA) that includes reliable messaging,
transactions, security, referral, licensing… for web
Q: EAI, CRM, B2B are exploding? What are your views
about these in related areas for the current and
A: Exploding? Of course there are some products in
these areas that are really hot-sellers. But there
is more need for EAI, CRM, B2B products; I still see
a lot of growth. The problem I have with existing
products is that they are too expensive and complex
for smaller companies. .NET makes it a lot easier to
build EAI, CRM, and B2B products, so I see great
opportunities for cheaper and not so complex
Q: For those relatively new in the computing field
and for seasoned veterans, which 10 areas should
they target for future study, what are the
high-growth areas, and can you provide specific
A: Web services are the most important part to look
into. This does not only mean to know XML, SOAP,
UDDI…, but also future infrastructure protocols and
SOAP modules where transactions, security, licensing
will be added to web services.
Many web applications that are now based on Active
Server Pages, Perl, Java Servlets and Java Server
Pages will be written with ASP.NET because the time
to market can be reduced. So Web Forms with ASP.NET
is another area that should be targeted for future
Small devices will get more and more important. With
hand-held devices Microsoft outperformed the
competition again. The .NET compact framework will
play an important role. To support such devices
across the Internet, and even small cellular phones,
the Mobile Internet Toolkit should be looked at.
Last but not least I expect the Tablet PC with pen
based input to become a huge success.
Q: What changes do you see for the future of
computing, conducting business, and the use of the
A: The Internet already changed our lives a lot, but
so far we have only seen the beginning. Information
at your fingertips will become reality. Today we can
be contacted by mobile phones no matter where we
are. In the future it will be completely normal to
have access to information at any place with any
Q: You are highly regarded and I have no hesitation
in recommending your book for the seasoned
professional. Please describe your book, how and
where they are available? How did you get involved
in being an author and what would be your 20 biggest
tips drawn from the book on C sharp? What additional
books are you planning in the near and far term?
What would you do different if you started again,
having gone through this authoring experience over
A: The book Beginning C# is intended for beginners
or relatively inexperienced programmers, e.g.
programmers who wrote scripts for ASP development.
This book explains the basic of C# programming and
shows an in-depth look into object oriented
programming. We also discuss the basics of Windows
programming, dynamic web pages, and web services.
This book can be bought in book stores, or on the
Web, e.g. http://www.amazon.com, or http://www.bookpool.com.
I have co-authored two books that are released soon:
Professional C# Web Services and Data Centric .NET
Programming with C#. Professional C# Web Services
covers both ASP.NET Web Services as well as .NET
Remoting. Data Centric .NET Programming with C#
provides information to create data-centric
applications and covers ADO.NET, XML, Active
Directory, Messaging Services, etc. At this stage I
cannot comment on my future plans, but you will read
With this authoring experience I have now I would
not change a lot. Maybe I would start writing books
earlier in my career path.
Q: What would be your recommended top ten references
for the serious developer?
Q: It’s a blank slate, what added comments would you
like to give to enterprise corporations and
A: Often I have seen project teams that used a good
technology, but they failed. Either the technology
was used in a wrong way, or they simply chose the
wrong technology for their problem. Many hours work
can be reduced by using the correct tool in a
correct way. The problem why these teams failed was
because of missing knowledge. Investment in good
training and consulting pays off easily!
Here are some interview questions with a focused
technical bent where I would be interested in your
1. Can you discuss .NET?
A: In the 70s our programs were written using
machine code using physical memory interrupt
handling for specific CPU’s. Using virtual memory,
threads and user-mode code added an abstraction to
the program development that made it much easier to
write applications. Managed code adds another
abstraction layer to application development. The
.NET compilers produce Microsoft IL code that can be
managed by the runtime. The runtime can check the
code at runtime for uninitialized variables, unsafe
casts, and deals with security, exceptions, memory
2. What’s the main benefit of .NET?
A: The .NET platform is a robust and secure
execution environment that dramatically simplifies
application development and also simplifies
deployment and management.
3. Give an overview of.NET?
A: There are many aspects of .NET to look at. With
.NET we not only talk about the .NET platform.
Microsoft server products are grouped in category
.NET Enterprise Server. Upcoming web services are
called .NET My Services. The successor of the
Windows 2000 Server is the Windows .NET Server. And
of course we have the .NET platform that is
available for nearly all Microsoft operating
systems, and can also be implemented by different
manufacturers as it was sent for standardization.
The essential parts of all these .NET products are
But let’s look at applications written for the .NET
platform. A .NET application consists of assemblies.
A .NET compiler creates assemblies that include
Microsoft IL code with metadata that describes the
assembly. When the application is started, the IL
code is translated to native code before it runs. It
is also possible to generate native code at
4. Define the Common Type System and .NET base class
A: The .NET runtime was designed to support multiple
programming languages. The Common Type System
defines rules how data types can be defined and such
used from different languages.
A: The .NET base class library has many
multi-purpose classes that can be used for any
application types, e.g. collection and thread
5. Overview the Common Language Specification and
the Common Language Runtime?
A: COM already supported multiple programming
languages. With COM it is possible to create a
component with C++, and use this component from
Visual Basic. Using COM we always had to develop the
component in a way that it could be used by the
target language. Each language has different
characteristics, so a scripting language can only
use IDispatch interfaces and cannot ask for
interfaces other from the default interface. That’s
different with .NET. The Common Language
Specification defines exactly what is needed to
support other languages. It is still possible that
we use the features of a language to some extent
which cannot be used by other languages. By setting
an attribute CLSCompliant which means that we are
compliant with the Common Language Specification it
is guaranteed that all other languages that support
.NET can use this component.
6. Does C++ worth with .NET?
A: Microsoft extended C++ in the ANSI spirit to
support .NET. .NET classes can be used from C++, and
it is possible to create .NET types with C++.
The advantage of Managed C++ compared to C# or
Visual Basic .NET is that this language can be used
to mix native and managed code – not only within a
program, but also within a class or within a method.
If there is an existent C++ class library, Managed
C++ is the best way to make this available for .NET.
7. Where does IL or Intermediate Language code come
into play with .NET?
A: The .NET Managed Compilers produce Microsoft IL
code that is translated to native code when the
program is started, or at installation time.
Contrary to the Java byte code, the Microsoft IL
code is not designed to be interpreted; it must be
compiled to native code.
8. Overview both metadata and reflection in .NET?
A: An assembly is described by its metadata that is
stored in the assembly itself. Using custom
attributes it is possible to store custom
information in an assembly that can be used at
design- or runtime by reading the metadata
information using .NET reflection. Examples where
such attributes are used are XML serialization to
define the XML elements and attributes how an object
should be stored, web service attributes that define
the WSDL information, COM+ attributes, etc.
9. How does a namespace differ from an assembly?
A: The name of an assembly and the namespace are two
completely independent concepts. The namespace is
used to uniquely identify types. The assembly has a
manifest with version, security, and culture
information. Classes from the same namespace can be
spread across multiple assemblies, and a single
assembly can hold classes from different namespaces.
10. Overview private and shared assemblies?
A: With COM all components can be found in the
registry where the path of the component can be
found. So in principle all COM components are
shared. With .NET we differentiate private and
shared assemblies. Private assemblies are copied
with the application; shared assemblies can be used
by multiple applications. With shared assemblies we
use a strong name to uniquely identify an assembly.
Part of this strong name is the version and a public
11. Overview unmanaged code and data?
A: We have to differentiate between managed code and
managed data. C# and Visual Basic .NET always
produce managed code. The Managed C++ compiler
generates both managed and unmanaged (native) code.
But this is different from managed data. With C# we
can use pointers to access .NET components. Using
pointers we have to pay attention that the garbage
collector doesn’t move the object where the pointer
points to in memory. We have to pin the object to a
fixed address. This is where unmanaged data comes
into play. Unmanaged data is not managed by the
12. Can .NET work with older software such as the
Win32 API and COM?
A: One of the major goals with the design of .NET
was the support of legacy software such as Win32 API
and COM. There’s no need for a complete rewrite of
existing components and libraries. COM and Win32 can
be easily used from within .NET. The same way it is
possible to use .NET components as COM components in
a legacy application.
13. Is there security in .NET?
A: Security is an important built-in concept with
.NET. Components can be downloaded from the
Internet, started from a network server, etc. .NET
security is based on the identity of the code, and
can be administratively configured via policies.
14. Overview application deployment in .NET?
A: Components no longer need the registry to store
information. Deployment can be as simple as an
xcopy. For an application only the assemblies and
configuration files must be copied. This doesn’t
mean that the Microsoft Installer technology makes
no sense anymore. If it should be possible to select
product directories and specific features for
installation, the Windows Installer adds a lot of
features for the installation of Windows
applications. How installer packages can be created
with Visual Studio .NET can be read in the book
15. Overview C#?
A: C# is a new language that is designed for .NET.
It follows many ideas from C++ and Java, but adds a
lot of new features that make it easier to create
16. Give us a history of the C#?
A: C played an important role as structural
programming language in the 70s. Stroustrup created
C++ by extended and adding features for object
orientation to the language. The new language C#
took the ideas from C++ without the necessity to be
compatible with C++ and added features for component
17. How is C# better than traditional C++?
A: With managed code it is no longer necessary to
deal with memory leaks, fragmented memory, etc.
18. What can’t you do with C#?
A: You cannot write device drivers with C#.
19. Overview how .NET is superior to using Microsoft
Foundation Classes (MFC) and Active Template Library
A: Writing programs using MFC and ATL you have to
know the libraries inside out. Instead of focusing
on the problem domain for the solution to be built
we have to know the inside of these libraries to a
large extent. That’s different with the .NET base
classes. They are a lot easier to use, but they are
also extendable if they don’t fit the purpose
exactly. Another big issue I like to mention is that
the .NET classes can be used from any languages. MFC
and ATL is built only for C++.
20. Overview System.Object, the common root of all
A: Unlike to C++ but similar to Java .NET has one
root class. This is the reason why every class
supports the methods of the base class
System.Object, e.g. ToString() to get the string
representation of a class. With the Object class it
is also possible that every object can be passed to
methods that accept an Object parameter. Useful
examples are methods of collection classes that can
manage objects of every type. The VARIANT type used
with COM is now obsolete.
21. In one sentence how does C# differ from C++?
A: C# adds syntax for a component based approach.
22. What does the preprocessor do in C#?
A: In C++ preprocessor is a heritage of C. With C++
there are a lot of features that make many parts of
the preprocessor obsolete; Macros and constants can
now be created differently. C++ just paid the price
for compatibility with C. Today the preprocessor
still is useful to differentiate build versions,
e.g. a debug and a release build of the code. For C#
a simple version compared to C++ of the preprocessor
is available to support different build versions.
23. Overview some complex data structures in C# and
compare to C++?
A: C++ really makes no difference between structs
and classes. With C# a very useful differentiation
was found: structs are value types, where classes
are reference types.
Because pointers don’t have the big use in C# as
they have in C++, arrays are much more powerful. In
C# we have a different syntax for rectangular
multi-dimensional and jagged arrays.
Strings are a very complex beast with C++. We have
to differentiate ASCII strings, DBCS, Unicode, BSTR,
etc. This gets easier with .NET: all the .NET
strings are Unicode.
24. Are pointers used in C#?
A: Pointers are an essential language construct with
C++, and often pointers are the reason for
programming errors. In most applications pointers
are no longer needed with C#. But there is a way to
use pointers with C# in unsafe code segments. This
can be especially useful if some complex methods in
legacy DLL’s must be called.
25. Overview value and reference types in C++ and
A: With C++ if a variable is put to the stack or the
heap depends on the declaration. Using a pointer and
the new operator with C++ results in a reference.
C++ does not make any differences with structs and
classes. With C# Microsoft found a good way to
distinguish between structs and classes. A struct
defines a value type, a class a reference type. In
contrast to Java we are no longer embarrassed to
create custom value types.
26. Overview dynamic memory allocation in C#?
A: With the new operator memory for reference types
is allocated on the heap. The garbage collector
manages the memory. It is not necessary that
allocated objects must be deleted because this is
the job of the garbage collector. The garbage
collector can reclaim the memory if there is no
longer a reference to the object. To boost the
performance of the garbage collector it uses a
generational model to differentiate the objects
based on their lifetime. For short-lived objects the
probability is higher that they are not needed
anymore on the next run compared to long-lived
27. Overview garbage collection in C#?
A: There is less need to implement destructors as
dynamically allocated memory will be freed
automatically. However if unmanaged resources are
used there is some code necessary that should run
when the object is destroyed. Here it is important
to pay attention to the behavior of the garbage
collector: the time when garbage collection happens
is not defined, the destructor code can be run by a
different thread, and the order of objects
destructed is not defined. Finalization code should
only be implemented if there are some unmanaged
resources that must be freed. Typically if a
destructor is added to the class, also the interface
IDisposable should be implemented to make it
possible to release the unmanaged resources at an
28. Overview the difference in inheritance between
C# and C++?
A: C# only supports single inheritance with classes,
C++ supports multiple inheritance. The rare case
where multiple inheritance is useful doesn’t justify
the problems multiple inheritance adds.
29. Overview polymorphism in C#?
A: Polymorphism is very similar to C++ with the
exception with C# there are more thoughts about
versioning because it is not necessary to recompile
the derived class if the base class changes. To
override a virtual method in a base class the
overrides keyword must be used.