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Unit 12: Building and Deploying an Information System
Networked (distributed) environment - Distributed processing divides the processing work notes
between two or more computers. The participating computers can be all mainframe, all midrange,
all micros, or, as in most cases, a combination they can be in one location or in several. Cooperative
processing is a type of distributed processing in which two or more geographically dispersed
computers are teamed together to execute a specific task. Another important configuration of
distributed processing is the client / server arrangement, where several computers share resources
and are able to communicate with many other computers via LANs. When a distributed system
covers the entire organization, it is referred to as an enterprise wide system and its parts are
frequently connected by an intranet.
A distributed environment with both mainframe and PCs is very flexible and is commonly
used by most medium and large-size organizations. This basic classification is analogous to a
transportation, such as a train or a plane. In this case, several riders share the vehicle and use it
at specified times and must obey several rules. This is like using a mainframe. Second, you can
use your own car, which is like using a PC. Third, you can use both; for example, you can drive
to the train station and take the train to work, or you can drive to the airport and take a plane to
your vacation destination. This last arrangement, which is analogous to a distributed system, is
flexible, providing the benefits of the other two options.
Thanks to communication networks and especially the Internet and intranets, networked
computing is becoming the dominant architecture of most organizations. This architecture
permits intra and inter-organizational cooperation in computing, accessibility to vast amounts
of data, information, and knowledge, and high efficiency in the use of computing resources. The
concept of networked computing drives today’s new architecture.
The Internet, intranet and extranets are based on client/server architecture and enterprise
wide computing, the newest architectural concepts. The principles of these concepts are briefly
explained in this section.
Client/Server Architecture - A client/server arrangement divides networked computing units
into two major categories: clients and servers, all of which are connected by LANs and possibly
VANs. A client is a computer such as a PC or a workstation attached to a network, which is
used to access shared network resources. A server is a machine that provides clients with these
services.
Example: Servers are a database server that provides connection to another network,
to commercial databases, or to a powerful processor. In some client / server systems there are
additional computing units, referred to as middleware.
The purpose of client/server architecture is to maximize the use of computer resources. Client/
server architecture provides a way for different computing devices to work together, each doing
the job for which it is best suited. The role of each machine need not be fixed; a workstation, for
example, can be a client in one task and a server in another. Another important element is sharing.
The clients, which are usually inexpensive PCs, share more expensive devices, the servers.
There are several modules of client/server architecture. In the most traditional model, the
mainframe acts as a database server providing data for analysis, done by spreadsheets, database
management systems, and other 4GLs, for the PC clients.
Client/server architecture gives a company as many access points to data as there are PCs on
the network. It also lets a company use more tools to process data and information. Client/
server architecture has changed the way people work in organizations; for example, people are
empowered to access databases at will.
Enterprise wide Computing - Client/server computing can be implemented in a small work area
or in one department on a LAN. Its main benefit is the sharing of resources within that department.
However, many users frequently need access to data, applications, services, electronic mail, and
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