Page 12 - DCAP312_WEB_TECHNOLOGIES_II

Web Technologies-II

Notes Visual Basic is the most popular language for developing applications with the DNA model, this
is used in two major roles forms based VB Clients and COM components. This VB6 language has
its own limitations it does not have the capability of multithreading, lack of OOPS concepts, Poor
error handling ability and poor integration with other languages. Hence it makes it unsuitable
for development of object based frameworks. Today’s applications need to use the Win32 API
for a variety of purposes like monitor widows messages, manipulate controls, reading and
writing to INI files and socket programming etc. But these widows API are hard to program
for variety of reasons, like it is not object oriented and complex calls to the functions with long
lists of arguments, since Win32 API is written in C++ language, getting calling conventions
right on data types is messy.
1.2.2 Limitations in DNA Based Internet Development or Browser Based
Clients

With DNA-based software development, creating software that is accessed by a user locally
is done very differently from development for the Internet. The Visual Basic forms for client-
server user interfaces versus the use of Active Server Pages for Internet user interfaces. Even
though both situations involve designing and implementing GUI based user interfaces the tools
and programming techniques used are quite different. ASP lacks in state management between
post backs.

Every time a page is rendered, the programmer must make sure that all the visual controls like
text boxes, dropdowns have their information loaded. It is the programmer’s responsibility to
manage the state in the user interface and to transfer state information between pages. This causes
developers to have to write a lot of code for the internet user interfaces that is not relevant to
business problem being solved. If the Internet application is going to run on a group of Web
Servers, then considerable additional work is necessary to design a state management system
that is independent of particular server.

Browser based clients are somewhat more difficult to create, and offer a more limited user
interface with fewer controls and less control over layout of the screen and handling of screen
events. It is possible to create rich user interfaces using DHTML, but it requires lot of coding
and also browser compatibility issues rises, for which a separate coding or two version of the
same page have to be maintained, keeping in mind, the browser we are targeting. The Internet
has caused server based applications to become much more popular than ever before and has
made the connectionless request/response programming model common. But communicating
between servers especially among those running on different platforms is difficult, and because
most substantial Internet applications are Database Centric, the ability to access a wide variety of
data sources easily is more important than ever. As we move on to handheld devices or wireless
devices, kiosks or other type of systems, many of which run a different processors and do not
use standard operating system. So sharing the data between these devices and communication
varies which is not uniform, becomes difficult.
1.3 .NET Philosophy

The driving force behind Microsoft .NET is a shift in focus from individual Web sites or devices
to new constellations of computers, devices, and services that work together to deliver broader,
richer solutions.
The platform, technology that people use is changing. Since 1992, the client/server environment
has been in place, with people running the applications they need on the Win32 platform, for
example. Information is supplied by the databases on the servers, and programs that are installed
on the client machine determine how that information is presented and processed.

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