ARCHITECTURE translates the logical
design of an information
system into a physical
structure that includes
hardware, software,
network support, and
SYSTEM
ARCHITECTURE
CHECKLIST
System Architecture
Checklist
Enterprise Resource Planning (ERP) –
The objective of ERP is to establish a
company- wide strategy for using IT
resources
The main advantage of ERP is that it
describes a specific hardware and software
environment, also called a platform, that
ensures connectivity and easy integration
Supply Chain Management (SCM)
System Architecture
Checklist
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 and ask the following
questions which can be seen in the
handouts.
System Architecture
Checklist
Scalability
– refers to a system’s ability
to expand, change or downsize easily to
meet the changing need of a business
enterprise
Also
called extensibility.
Especially
important in implementing
systems that are volume-rated, such as
transaction processing systems
System Architecture
Checklist
Web Integration - An information system
includes applications
program that handles the input, manage
the processing logic, and provide the
required output
Web-centric architecture
Avoids many of the connectivity and
compatibility problems that typically arise
E-marketplaces
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
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
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
PLANNING THE
ARCHITECTURE
Planning the Architecture
Servers
– is a computer that supplies data,
processing services, or other support to one
or more computers, called clients.
Mainframe
Architecture
– a system design where the server
sometimes performs all the processing.
Planning the Architecture
Server-based Processing – Companies
installed terminals at remote locations, so
that users could enter and access data
from anywhere in the organization,
regardless of where the centralized
computer was located
Terminal – included a keyboard and
display screen to handle input and output,
but lacked independent processing
capability
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
Planning the Architecture
Stand-Alone
Computing – when an
individual user works in stand-alone
mode, the workstation performs all
functions of a server by storing,
accessing, and processing data, as
well as providing a user interface.
Planning the Architecture
Local
and Wide Area Networks
◦ Local Area Network (LAN) – allows sharing of
data and hardware resources
◦ Wide Area Network (WAN) – spans long
distances and can connect LANs that are
continents apart
When a user access data on a LAN or WAN, the
network is transparent because a user sees the
data as if it were stored on his or her own
workstation. Company-wide systems that connect
one or more LANs or WANs are called distributed
systems
Planning the Architecture
Client-Based
Processing
As LANs became popular, the most common LAN
configuration was a file server design. In a file
server design, also called a file sharing
architecture, an individual LAN client has a copy
of the application program installed locally,
while the data is stored on a central file server
Client/Server
Architecture
Client/Server Architecture
Client/Server Architecture - Refers to
systems that divide processing between on
or more networked clients and a central
server
Fat and Thin client
Fat client – also called thick client, locates
all or most of the application processing
logic at the client
Thin client – locates all or most of the
processing logic at the server
Client/Server Architecture
Client/Server
Tiers
◦ Two-tier - UI resides on the client, all data
resides on the server and application logic
can run on either or be divided between
the two
◦ Three-tier – also called n-tier design,
has middle layer between client and server
Client/Server Architecture
Middleware
– Enables the tiers to communicate and
pass data back and forth
Provides a transparent interface
- Can integrate legacy systems and Webbased applications
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
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
Internet-Based
Architecture
Internet-Based
Architecture
Developing E-Commerce Solutions In-House
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
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
Processing
Methods
Processing Methods
Online
Processing
- Handles transaction when and where
they occur and provides output directly to
users
– 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
Processing Methods
Batch
Processing
- Data is collected and processed in
groups or batches
– 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
Network Models
Network Models
Network
– allows the sharing of hardware,
software and data resources in order to
reduce expenses and provide more
capability to users
Network Models
Open
System Interconnection
(OSI) Reference Model
– Describes how data actually moves
from an application on one computer to an
application of another networked computer
- The OSI model consists of seven layers
– Each layer performs a specific function
– Offers a set of design standards
Network Models
7
layers of OSI
◦ Application Layer
◦ Presentation Layer
◦ Session Layer
◦ Transport Layer
◦ Network Layer
◦ Data Link Layer
◦ Physical Layer
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
- Microsoft Visio
Network Models
Network
Topology – the way a network is
configured. LAN and WAN networks are
typically arranged in four patterns:
A. 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
Network Models
B. STAR NETWORK
- has a central computer with network
devices connected to it
- Hub is the center and it manages the
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
Network Models
C. 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
Network Models
D. RING NETWORK
- resembles a circle of computers that
communicate with each other
- 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)
Network Models
Network
Protocols
– In all cases, the network must use a
protocol, a set of standards that govern
network data transmission
– Transmission Control Protocol/Internet
Protocol (TCP/IP)
– File Transfer Protocol (FTP)
Licensing
Issues
Wireless
Networks
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)
– Basic Service Set (BSS) – infrastructure
mode
– Access point
– Extended Service Set (ESS)
– Roaming
– Independence Service Set (ISS) – peerto-peer mode
Wireless Networks
Wireless
Trends
– 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
System
Management and
Support
System Management and
Support
Performance
Management
– tools are designed to collect
information about system resources and
activity levels
- A performance management tool can
monitor system usage, capacity, and trends.
It also includes fine tuning the network
configuration or software settings to
optimize performance.
System Management and
Support
Fault
Management
- Main concern is to detect and resolve
operational problems as quickly as possible.
- The task includes monitoring the
system for signs of trouble, logging all
system failures, diagnosing the problem and
applying corrective actions.
System Management and
Support
Backup
– refers to copying data continuously or at
prescribed intervals
Recovery
Procedures
– involve restoring the data and restarting the
system after an interruption
An overall backup and recovery plan is often
called a disaster recovery plan.
System Design
Completion
System Design Completion
System
Design Specification
– A typical system design specification
uses a structure similar to the following:
1.
2.
3.
4.
5.
6.
Executive Summary
System Components
System Environment
Implementation Requirements
Time and cost estimate
Appendices
System 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
System 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