CIS 325: Data Communications 1

CIS-325Data Communications

Dr. L. G. Williams, Instructor

CIS 325: Data Communications 2

Chapter Fourteen

Client-Server & Intranet Applications

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Client-Server Basics

Clients are usually single-user PCs or workstations, with GUIs

Servers enable many clients to share access to the same data

Network provides communication services between clients and server (“many to one”)

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Client-Server Characteristics

Strong emphasis on bringing user-friendly, familiar apps and interface to the user

Applications are distributed, but data is centralized

Encourages the use of open and modular systems

Networking is fundamental to the process (“the network is the computer”)

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Advantages of Client-Server Computing

Distributed systems means redundancy and robustness

Distributed processing provides power without monopolization of resources

Modularity allows choices in hardware and software

Upgrading and growth are relatively easy

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Disadvantages of Client-Server Computing

Maintenance problems are more difficult with different vendors and interconnected systems

Difficult to find support tools for applications developed in-house

Requires different skills sets from software developers (Windows, Mac, RDBMS rather than COBOL, C)

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Client-Server Architecture

Protocols at the communication and application layers must be compatible

Hardware, operating systems, and software presentation layers can operate independently of each other– Note: In this context, presentation has to do with

the application’s presentation of information to the user, not the presentation layer of the OSI model, which is concerned with formatting data

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Classes of Client-Server Applications

Host-based processing– traditional

mainframe/central host environment; workstation role is limited to emulation

Server-based processing– Client primarily provides

interface

Client-based processing– All application

processing on client

Cooperative processing– Processing distributed

optimally

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Intranets Implementation of Internet technologies

within an organization Primarily focused on web development,

with database integration Growing at a tremendous rate

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Intranet Advantages

Easy and fast development of new services

Not locked into specific vendor products Improved ability to communicate outside

organization Familiar, inexpensive interface IDC has found that Intranets can result i

n ROI of as much as 1000%

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Typical Intranet Applications

Access to corporate databases Organization and presentation of

documentation Communication

– Intranet group mail products, eg Notes & First Class

– Usenet news, implemented with local groups– Threaded bbs-style implementations

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Client-Server Problems

Long development cycle Difficult to partition apps. Difficult to distribute upgrades Servers don’t scale up PCs must continue to grow