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Network Computing - Is It Simply a Different Form of Client/Server?

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The key to understanding client/server architecture and client/server systems

is the distinction of where the presentation, presentation logic, application

logic, data manipulation, and data layers are distributed among the client PC

and one or more servers. The key to understanding Internet-based computer

architectures and network computing systems is grasping the use of multi-tier

solutions. Internet-based computer architectures distribute the five layers

(mentioned previously) amongst web, application, and database servers. Because

the client PC does not implement any of these layers (the Web browser implements

the presentation and presentation logic layers downloaded from a Web server), it

can be considered that network computing is NOT a form of client/server. Knowing

the headaches that can arise with software installations and client/server

architecture, Internet-based computer architecture and open-source Internet

technology is said to deliver inter-operational efficiency and plug-and-play

convenience.

Client/server systems are defined as a "solution which the presentation,

presentation logic, application logic, data manipulation, and data layers are

distributed between the client PC and one or more servers" (Whitten,

Bentley, Dittman, 2001). Clients are classified as either being "thin"

or "fat". "Thin" clients act as terminals and only present

the interface to the user (typically, these clients do not have hard drives).

"Fat" clients are personal or notebook computers with powerful

processors, memory, and storage capacity. Servers are classified as database

(for shared databases and command/services execution), transaction (for ensuring

business transactions either succeed or fail), application (hosts application

logic/services), messaging (email/workgroup), and Web (hosts Internet or

intranet Web sites).

There are three distinct classes of client/server architectures - distributed

presentation, distributed data, and distributed data and application.

Distributed presentation is typical of older legacy systems using character user

interface where it is desired to present a graphical user interface to run on a

PC. The server handles the application logic, data manipulation, and data

layers. The client handles the presentation and presentation logic layers.

Distributed data is known as "two-tiered" client/server computing

because there is a server (i.e. Oracle or Microsoft SQL Server) that handles the

data and data manipulation layers and the client handles the application logic,

presentation, and presentation logic layers). Distributed data and application

client/server systems are known as "three-tiered" client/server

computer because there are two servers (one that handles application logic and

one that handles data and data manipulation) and the client handles the

presentation and presentation logic layers.

Internet-based computing architectures consist of network computing systems.

Network computing systems are considered "multi-tiered" because there

are three types of servers that enable the client to implement a client-side Web

browser that uses content downloaded from a Web server. The Web server handles

the presentation and presentation layers implemented in the client-side Web

browser. There is also an application server for application logic and a

database server for data and data manipulation. Network computing systems can be

utilized for Internet, intranet (secure internal network for integrating

desktop, work group, and enterprise computing), and extranet (external systems

connecting to internal company information) services.

References:

Kersnar, Scott. (2001, March). Web Versus Windows: Does the mortgage industry

need to jump from client-server to Internet technology? Or is the ASP solution

not everyone's solution?. Mortgage Technology.

Whitten, Jeffrey; Bentley, Lonnie; Dittman, Kevin. (2001). Systems

Analysis and Design Methods. New York, NY. McGraw-Hill Companies, Inc.

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