Transcript PPT - Regis University: Academic Web Server for Faculty

CIS-425: Systems Analysis and
Design
Week 6
Dr. Jesús Borrego
Lead Faculty, COS
Regis University
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scis.regis.edu ● [email protected]
Class Outline
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Questions on material covered
Key Terms
Chapter 10: System Architecture
Activity 1
Project Updates
Questions?
Homework Questions
• Questions on homework or assignments?
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Questions on material covered?
• How to create a web page?
• How to create schedules with Project?
• How to create diagrams with Visio?
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Key Terms
• See p. 491
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Systems Analysis and Design 9th
Edition
Chapter 10
System Architecture
scis.regis.edu ● [email protected]
Chapter Objectives
• Provide a checklist of issues to consider when
selecting a system architecture
• Describe servers, server-based processing,
clients, and client-based processing
• Explain client/server architecture, including
tiers, cost-benefit issues, and performance
• Compare in-house e-commerce development
with packaged solutions
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Chapter Objectives
• Discuss the potential impact of cloud computing
and Web 2.0
• Explain the difference between online and batch
processing
• Define network topology, including hierarchical,
bus, ring, and star models
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Chapter Objectives
• Explain network protocols and licensing issues
• Describe wireless networking, including wireless
standards, topologies, and trends
• Describe the system design specification
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Introduction
• An effective system combines elements into an
architecture, or design, that is flexible, costeffective, technically sound, and able to support
the information needs of the business
• System architecture translates the logical design
of an information system into a physical
structure that includes hardware, software,
network support, and processing methods
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System Architecture Checklist
• Enterprise Resource Planning (ERP)
▫ The objective of ERP is to establish a companywide strategy for using IT resources
▫ Supply chain management (SCM)
• Initial Cost and TCO
▫ During the final design stage, you make decisions
that will have a major impact on the initial costs
and TCO for the new system
▫ You should review all previous cost estimates
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System Architecture Checklist
• Scalability
▫ Scalability, also called extensibility, refers to a
system’s ability to expand, change or downsize
easily to meet the changing need of a business
enterprise
▫ Especially important in implementing systems
that are volume-rated, such as transaction
processing systems
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System Architecture Checklist
• Web Integration
▫ An information system
includes applications
▫ Web-centric architecture
▫ Avoids many of the
connectivity and
compatibility problems that
typically arise
▫ E-marketplaces
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System Architecture Checklist
• Legacy System Interface Requirements
▫ The new system might have to interface with one
or more legacy systems
▫ Interfacing a new system with a legacy system
involves analysis of data formats and compatibility
▫ The analyst must know if the new application
eventually will replace the legacy system
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System Architecture Checklist
• Processing Options
▫ In planning the architecture, designers also must
consider how the system will process data - online
or in batches
▫ Provision must be made for backup and speedy
recovery in the event of system failure
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System Architecture Checklist
• Security Issues
– Security threats and defenses
are a major concern to a
systems analyst
– The analyst must consider
security issues that relate to
system design specifications
– Web-based systems introduce
additional security concerns
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Planning the Architecture
• Servers
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Server
Clients
Mainframe architecture
Server-based processing
Planning the Architecture
• Clients
▫ As PC technology exploded in the mid-1980s and
1990s, powerful microcomputers quickly appeared
on corporate desktops
▫ Users found that they could run their own word
processing, spreadsheet, and database
applications
▫ Companies linked the stand-alone computers into
networks
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Planning the Architecture
• Clients
▫ Stand-Alone Computing
▫ Local and wide area networks
▫ Client-based processing
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Client/Server Architecture
• Overview
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Client/Server Architecture
• Client/Server Design Styles
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Client/Server Architecture
• Fat and Thin Clients
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Client/Server Architecture
• Client/Server Tiers
– Two-tier design
– Three-tier design
• Middleware
– Enables the tiers to communicate and pass data
back and forth
– Provides a transparent interface
– Can integrate legacy systems and Web-based
applications
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Client/Server Architecture
• Cost-Benefit Issues
▫ Client/server systems enable the firm to scale the
system in a rapidly changing environment
▫ Client/server computing also allows companies to
transfer applications from expensive mainframes
to less expensive client platforms
▫ Client/server systems reduce network load and
improve response times
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Client/Server Architecture
• Client/Server Performance Issues
– In contrast to the centralized system, a
client/server design separates applications and
data
– Distributed database management system
(DDBMS)
– The system is scalable, so new data sites can be
added without reworking the system design
– The system is less likely to experience catastrophic
failure
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Activity 1
• 1 hour video: Take notes
• Anatomy of a Design Decision (65:29 min.):
http://video.esri.com/watch/2228/keynote-addressanatomy-of-a-design-decision
• Write the top 3 topics/ideas (3 good, 3 bad) that stuck in
your mind
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Internet-Based Architecture
• Developing E-Commerce Solutions In-House
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Internet-Based Architecture
• Packaged Solutions and E-commerce Service
Providers
▫ Many vendors offer turnkey systems for
companies
▫ Another alternative is to use an application service
provider (ASP)
▫ Another option is managed hosting
▫ Consider the experience of other companies in the
same industry
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Internet-Based Architecture
• Corporate Portals
– A corporate portal can
provide access for customers,
employees, suppliers, and the
public
• Cloud Computing
– Effectively eliminates
compatibility issues
– Scaling on demand
– Requires significantly more
bandwidth
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Internet-Based Architecture
• Web 2.0
▫ Envisions a second
generation of the web that
will enable people to
collaborate, interact, and
share information more
dynamically
▫ Wiki
▫ Internet operating system
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Processing Methods
• Online Processing
▫ Because it is interactive,
online processing avoids
delays and allows a constant
dialog between the user and
the system
▫ Online processing also can be
used with file-oriented
systems
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Processing Methods
• Batch Processing
▫ The IT operations group can run batch programs
on a predetermined schedule, without user
involvement, during regular business hours, at
night, or on weekends
▫ Require significantly fewer network resources
than online systems
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Processing Methods
• Combined Online and Batch Processing
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Network Models
• The OSI Reference Model
▫ The OSI model consists of seven layers
▫ Each layer performs a specific function
▫ Offers a set of design standards
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Network Models
• Network Protocols
▫ In all cases, the network must use a protocol
▫ Transmission Control Protocol/Internet Protocol
(TCP/IP)
▫ File Transfer Protocol (FTP)
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Network Models
• Network Topology
▫ Hierarchical network
 it mirrors the actual
operational flow in the
organization
 One disadvantage of a
hierarchical network is that
if a business adds additional
processing levels, the
network becomes more
complex and expensive to
operate and maintain
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Network Models
• Network Topology
▫ Bus network
 Devices can be attached or
detached from the network
at any point without
disturbing the rest of the
network
 Overall performance
declines as more users and
devices are added
 Today, the bus design is
much less popular
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Network Models
• Network Topology
▫ Ring network
 One disadvantage of a ring
network is that if a network
device fails (such as a PC or
a server), the devices
downstream from the failed
device cannot communicate
with the network
 Multistation Access Unit
(MAU)
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Network Models
• Network Topology
▫ Star network
 Disadvantage of the star
design is that the entire
network is dependent on the
switch
 However, in most large star
networks, backup switches
are available immediately in
case of hardware failure
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Network Models
• Network Topology
▫ Mesh network
 While this design is
extremely reliable, it also is
very expensive to install and
maintain
 Originally developed for
military applications
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Network Models
• Routers
▫ Routers differ from switches
in that they work at a higher
OSI level
▫ Can connect to a larger,
dissimilar network, such as
the Internet
▫ Gateway
▫ Proxy server
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Network Models
• Network Modeling Tools
▫ As you translate the OSI
logical model into a physical
model of the networked
system, you can use software
tools
• Network Licensing Issues
▫ Software licensing
restrictions
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Wireless Networks
• A wireless local area network, or WLAN
• Wireless Network Standards
▫ 802.11
▫ Institute of Electrical and Electronics Engineers
(IEEE)
▫ Amendments
▫ Mbps (megabits per second)
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Wireless Networks
• Wireless Network Standards
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802.11g
802.11n
Multiple input/multiple output (MIMO)
Multipath design
802.11y
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Wireless Networks
• Wireless Network Topologies
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Basic Service Set (BSS) – infrastructure mode
Access point
Extended Service Set (ESS)
Roaming
Independence Service Set (ISS) – peer-to-peer
mode
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Wireless Networks
• Wireless Trends
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Wi-Fi Alliance
Wi-Fi (wireless fidelity)
BlueTooth
On addition to 802.11 protocols for LANs, IEEE is
working on 802.16 standards
▫ MANs (metropolitan area networks)
▫ WiMAX
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Systems Design Completion
• System Design Specification
▫ A typical system design specification uses a
structure similar to the following:
1.
2.
3.
4.
5.
6.
Management summary
System components
System environment
Implementation requirements
Time and cost estimates
Additional material
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Systems Design Completion
• User Approval
– Users must review and approve the interface
design, report and menu designs, data entry
screens, source documents, and other areas of the
system that affect them
– Other IT department members also need to review
the system design specification
– When the system design specification is complete,
you distribute the document to a target group of
users, IT department personnel, and company
management
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Systems Design Completion
• Presentations
– The first presentation is to the systems analysts,
programmers, and technical support staff members
– Your next presentation is to department managers and
users from departments affected by the system
– The final presentation is for company management
– Management might reach one of three decisions:
proceed with systems development, perform
additional work on the systems design phase, or
terminate the project
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Chapter Summary
• An information system combines hardware,
software, data, procedures, and people into a
system architecture
• The analyst must consider enterprise resource
planning, initial cost and TCO, scalability, Web
integration, legacy interface requirements,
processing options, and security issues
• An architecture requires servers and clients
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Chapter Summary
• Compared to file server designs, client/server
systems are more scalable and flexible
• In implementing a design, an analyst should
consider e-commerce strategies, the availability
of packaged solutions, and corporate portals,
which are entrances to a multifunction Web site
• The primary processing methods are online and
batch processing
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Chapter Summary
• Networks allow the sharing of hardware,
software, and data resources in order to reduce
expenses and provide more capability to users
• The way a network is configured is called the
network topology
• The system design specification presents the
complete systems design for an information
system
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Activity 2
• 3 Web Design Tips (5:19 min.):
http://www.youtube.com/watch?v=Kkg0Jx72M48
• What Makes Good Web Design? (2:05 min.):
http://www.youtube.com/watch?v=UHpyES6Jbx0
• Web Design Mock-Up Walk-Through (9:43 min.):
http://www.youtube.com/watch?v=kBTx7VP66Go
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Activity 3
• Top Level Design Activities:
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Process Design
Network Design
Database Design
Web Design
Form Design
Report Design
• Detailed Design Activities:
▫ Next level for each
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Project tasks
ClassPhase
1 Introduction
Activity
Prepare interview questions
Conduct Customer
2 Project Scope
Determine project
Interview
Present project scope to
3 Requirements
Project Specification
customer
4 Top Level Design Determine design
Specification to customer
5 Detailed Design Develop components
Top level design
6 Architecture
Final Proposal
Detailed design
7 Management
Complete project
Final Project design
8 Implementation Final Project Presentation Final Project presentation
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Description
Problem Statement
Questions?
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