Chapter 10

10-1

Chapter 10

Site Architecture

McGraw-Hill/Irwin Copyright © 2004 by The McGraw-Hill Companies, Inc. All rights reserved.

10-2Site ArchitectureSite Architecture Issues Issues

• Logical architecture.• Factors involved in choosing a logical

architecture?• The presentation layer.• The business logic layer.• The data layer.• Factors involved in choosing a

physical architecture.

10-3Logical vs. Physical ArchitectureLogical vs. Physical Architecture

• Logical Architecture Defines the software components and

the desired functionality of those components in a site

• Physical Architecture Defines the hardware and third-party

software needed to host and maintain a website

10-4Logical ArchitectureLogical Architecture

Four main logical models have evolved over the years:

• Mainframe: systems are built around a single, monolithic computer that is shared by all users on the system

• Client/Server: a central server is used to store information that is accessed and acted upon by any number of client machines connected to the server through a network

10-5Mainframe ArchitectureMainframe Architecture

Dumb Terminals (no CPU)

Single Mainframe Computer

10-6Client/Server ArchitectureClient/Server Architecture

PC Workstations

Single Central Server

10-7

• N-Tier: compartmentalizes different functions of a system into modules that interact with one another

• Distributed: is a system of servers, loosely coupled across a dispersed network, that work together to deliver a website

Logical ArchitectureLogical Architecture

10-8N-Tier ArchitectureN-Tier Architecture

Presentation LayerBusiness Logic Layer

Data Layer

PCs with Web Browsers

10-9Distributed ArchitectureDistributed Architecture

Three-Tier System

PCs with Web BrowsersExternal Payment

Processing

Internal Inventory System

Internal Link

External Link

10-10Choosing an ArchitectureChoosing an Architecture

• A number of factors can influence this decision, they can include: Functionality: refers to the functions that a system must

implement

Flexibility and Adaptability: refer to the ability of a system to adapt to changes in its function

Scalability: refers to the ability of a system to be extended to handle a greater load, usually as a result of an increase in the user base

Performance: is the perceived speed of a system, often measured by the user as response time

Maintenance: refers to the monitoring and updating of a system

10-11Choosing an ArchitectureChoosing an Architecture

Required Skills: refers to the skills needed to design, build, and maintain a system

Security: refers to the ability of a system to prevent illegal or inappropriate use of its data and to deter hackers

Reliability: refers to the amount of time a system can be expected to be available to users

Metrics: are the measurements and data needed by the company to understand the operation of a system

Cost: is the amount of money spent to design, build, and maintain a system

Time: refers to the number of people/hours, as well as total time period, needed to develop a system

10-12Three-Tier ArchitectureThree-Tier Architecture

Web Server

Payment User/Admin Content

Database

Presentation

Business Logic

Data

Modules

10-13The Data LayerThe Data Layer

• The main function of the data layer is to provide fast, reliable access to data needed to run a system

• Additionally, the data layer is responsible for maintaining information about the relationships between data

10-14Types of DatabasesTypes of Databases

• Flat-File: are single computer files that store all of the information for a system

• Relational: data are stored in a series of tables, each table stores a discrete piece of data for the system

• Object Oriented: encapsulates all data into different types of objects

10-15Choosing a DatabaseChoosing a Database

• To choose the right database several factors must be weighed: Load/Storage Capacity Type of Data Speed Cost Reliability

10-16The Business-Logic LayerThe Business-Logic Layer

• The business-logic layer is responsible for implementing the basic rules of the system according to the operating rules of the business

• This layer is often divided into a number of submodules, each handling different aspects of the system

10-17The Presentation LayerThe Presentation Layer

• The presentation layer is responsible for all communications with the user’s computer Renders the content from the DB

• The most common ways to present data to site users are: HTML Third-party Plug-ins Homegrown Plug-ins

10-18External SystemsExternal Systems

• Kinds of systems most often connected with a companies site include: CRM Payment Processing Shipping Fulfillment Inventory Financial Human Resources B2B Exchanges Outside Suppliers

10-19Physical ArchitecturePhysical Architecture

Hardware• When choosing hardware, a number

of factors must be considered: Platform Power Hosting

10-20Hosting AlternativesHosting Alternatives

• Free: Hosts offering free service (ex.,

geocities.yahoo.com) Good for very simple sites (personal

homepages)• Shared Server:

Many websites are placed on the same Web server

Good for small businesses looking for increased capabilities

• Dedicated Server: Website is allocated its own dedicated server Good for larger websites

10-21Hosting AlternativesHosting Alternatives

• Co-located Server: Offers companies the most control over the

hardware running the site Customer owns server and is only paying for

bandwidth and a physical space for the server• In-house:

Good for companies with adequate resources (Global 1000 companies)

Sites need 24-hr dedicated personnel, power backup, security maintenance, and redundancy

10-22Hosting for Large WebsitesHosting for Large Websites

• Most large websites are hosted by third-party facilities

• The main service offered by these companies is reliability

• Typical service offerings from third party companies include: Redundant Internet Connections Backup Power Physical Security Server Management Services Offsite backup Storage