E-volution of Computing Architecture and Applications

Phase I: Mainframe and legacy computing

It all started in the 1960s with mainframe and legacy computing. The
mainframe model is a fully centralized architecture in which a central system
performs all of the processing and contains all of the data. Users access this
system through ‘dumb terminals’.

As legacy systems e-volved, we saw the transition into distributed
minicomputer architecture, which is a medium-scale computer that functions as a
multi-user system for up to several hundred users. The minicomputer era also saw
organizations focus on the internal functions of the enterprise.

Indian IT vendors were very hardware-centric in those days, offering limited
Unix-based coding engagements to organizations that were largely focused on
internal functions such as selling, building, or delivering the product or

Companies such as Tata Consultancy Services (TCS) and HCL Infosystems were
two of the few Indian names, which focused on hardware and hardware enabling
tools during this era.

Legacy systems demand very batch-oriented processing codes. These
applications were command-specific, rigid, and tailored to the device which they
were driving. Procedure-based programming languages in vogue during this era
included UNIX, PASCAL, and COBOL.

Phase II: Client-server

The next large-scale paradigm shift gained momentum in the 1980s with the
introduction of client-server technologies where the client (PC) is the
requesting machine and the server is the supplying machine, both of which are
connected via a local area network (LAN).

IT services demand boomed for migration work into this latest era of
computing–one which still dominates the corporate enterprise today.

The global demand surge for migration work and client-server applications saw
a major boom in Indian IT service providers, and the onset of a hardware-centric
focus to one based on services, reengineering, and application development.
Companies such as Infosys Technologies, founded in 1981, were ushered in by this

The migration to client-server architecture brought with it an onslaught of
creative, object-oriented programming languages. C, C++, SQL Server, and
Microsoft’s Visual Basic introduced the use of more modular and flexible
programming. While a big improvement from procedure-based command-specific code,
these applications were still largely device-specific.

Phase III: E-volution driven by the Internet

As client-server architecture evolved, servers took on more of the processing
of applications. The Internet age and thin-client architecture emerged, and we
find ourselves back in an era of powerful servers dedicated to running entire

Thin client architecture, true to its name, implies that virtually all heavy
processing will migrate from the user’s (or client’s) desktop to more
powerful Web servers–leaving the client-end thin and opening the path to
device neutrality or the use of personal digital assistants (PDA) and mobile

Internet-enabled thin-client architecture is influencing organizations to
reorganize themselves around business processes such as order fulfillment and
product development, reducing the importance of functional boundaries. Embracing
the e-volution means that businesses need to ‘Webify’ their existing
platforms and business processes to facilitate any-to-any connectivity.

Internet-based thin-client applications are open platform-based and extremely
flexible. Using the Internet as a platform means adopting Internet standards
which can be used by anyone (i.e., they are open); hence allowing developers to
break away from proprietary standards like those of Microsoft. In this wave of
computing, programmers have started writing software for browsers instead of a
rigidly defined environment such as Windows.

These new object-oriented programming languages include COBRA/DCOM, Java,
HTML, and XML. And, as stressed above, they are device neutral–they can talk
to computers, TV sets, and PDAs.

In essence, applications enabling thin clients allow complete many-to-many
interactivity and total platform ubiquity.

Internet-based applications are differentiated. Internet-based e-business
applications differ from client-server applications in that they leverage
Internet architecture to enable organizations to electronically sell, purchase,
support, and understand their customers, suppliers, employees, and partners.

With the Internet, companies will be able to organize themselves around two
critical architectures–the intranet and the extranet. The intranet utilizes
Internet technology to facilitate internal communication. The extranet utilizes
the Internet to communicate with parties outside the organization.

From an application perspective, Internet architecture has three tiers–client,
application, and data. The client tier is browser-based and is described as ‘thin’
because little or no business logic runs on the client level. It is somewhat
analogous to the dumb terminal connected to a mainframe. The thin-client tier is
important because it enables the application to run on many different, often
non-traditional, devices including PDAs, pagers, and mobile phones, in addition
to PCs.

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