P1: IML
Owen WL040/Bidgolio-Vol I WL040-Sample.cls June 20, 2003 17:37 Char Count= 0
VISUALBASIC.NET—VISUALBASIC FORINTERNETAPPLICATIONS 617database, as well as dBASE III, dBASE IV, dBASE 5.0,
Excel, FoxPro, Lotus, Paradox, and text file formats. With
the addition of Open Data Base Connectivity, Visual Basic
can access a wider range of database systems such as SQL
Server, Oracle, and DB2 (Bradley & Millspaugh, 1998).
With the release of Visual Basic.NET, all data access
is controlled through the .NET framework. The data are
combined with the programs needed to access and manip-
ulate the data. This data and programs unit is then treated
as an object. The data corresponds to the data component
of an object and the programs correspond the methods
component of an object.VISUAL BASIC.NET—VISUAL BASIC
FOR INTERNET APPLICATIONS
Visual Basic through Version 6.0 has established itself as
a significant player in Windows programming. As com-
puter information systems evolve toward Web and In-
ternet technology-based data delivery, Visual Basic has
evolved with them. Microsoft has taken a significant step
in this evolution with the release of Visual Basic.NET.
Understanding the differences between Visual Basic.NET
and previous Visual Basic releases requires an under-
standing of Microsoft’s .NET framework.
Simply stated, .NET is Microsoft’s platform for build-
ing XML Web Services. The goal of .NET is to provide
a platform, or framework, for developing and deploying
Web-based data delivery services, called Web Services, in
a simple, secure, and consistent manner. Although Web
Services are the central thrust of .NET, Visual Basic.NET
can be used for much more than building applications that
create and consume Web Services (Evjen & Beres, 2002).
Software has become a service in today’s computing en-
vironment, prompting a paradigm shift. Buying a shrink-
wrapped software package off the store shelf is giving
way to buying software services that are delivered over
the Internet or Internet-like connections (Evjen & Beres,
2002). Instead of a box of CDs or DVDs, software will
be purchased via the Internet and downloaded directly
into the computer when needed. The software service will
provide support and product updates via the same Inter-
net mechanism. Creating these Web Services is the next
step in application development evolution. For the Inter-
net to be an effective and efficient data delivery mecha-
nism, a common communications method, or protocol,
is needed. This protocol must support a wide variety of
transactions without regard to the hardware, operating
system, or browser employed. Hypertext transfer proto-
col, or HTTP, has existed for many years and is an estab-
lished Internet data exchange protocol. It is well suited
to data delivery across the Internet. The simple object ac-
cess protocol, SOAP, was the first attempt at a standard
protocol to move data over the HTTP transaction trans-
port mechanism. SOAP is an XML-based specification for
sending and receiving data over the Internet. XML is a
self-describing text file that can be understood by any op-
erating system or browser. Using the SOAP specification to
format data and the HTTP protocol to transport them, any
Web site can offer data-related services. SOAP formatted
requests are sent to the server via the HTTP protocol. Theserver responds via XML within the SOAP framework,
using HTTP to deliver the XML response. XML’s broad
application across many different hardware and software
platforms will give the .NET initiative great appeal to a
wide range of end users. Simple handheld devices capable
of running browser software will rival laptop and desktop
computer systems in data access capabilities. This should
further speed .NET’s acceptance (Evjen & Beres, 2002).
To the developer, the .NET initiative has different ram-
ifications. All application development will now occur on
the server side of the Internet. Applications will no longer
be installed on client computers. The client will run only
a browser. Applications will either run on the server and
push data to a browser, or download from the server and
execute in a browser. Applications must be specifically de-
signed with this Internet delivery in mind. If design and
development of .NET-ready applications is difficult and
costly, .NET will never gain acceptance. Anticipating this,
Microsoft created several tools to aid in .NET application
development. Visual Studio.NET, which contains Visual
Basic.NET, provides programming tools that can easily
and quickly create Web Services.
XML is such a basic component of .NET that a mastery
of it would seem to be essential to successful .NET devel-
opment. Actually, the XML portions of .NET are buried in
the .NET framework. Application developers use tools like
Visual Studio.NET, which automatically generate needed
XML. .NET programmers can create Web Services with
no knowledge of XML. This makes Visual Basic.NET and
the other languages in Visual Studio.NET true RAD tools
on both the client and server sides (Evjen & Beres, 2002).The .NET Framework
The .NET framework is a collection of components
needed to create Web Services. Figure 3 shows the key
.NET framework components (Evjen & Beres, 2002).
Of specific interest are the common language Runtime
and its base class library. A basic understanding of as-
semblies and name spaces is also useful in understanding
.NET programming (Aitken & Syme, 2002).The Common Language Runtime
There are currently approximately 18 languages that
support the .NET initiative (Evjen & Beres, 2002). All
.NET applications, regardless of the language they wereFigure 3: .NET framework.