system architecture.ppt

PowerPoint Presentation for Dennis, Wixom & Tegarden Systems Analysis and Design
Copyright 2001 © John Wiley & Sons, Inc. All rights reserved.
Slide 1
System Architecture Design
Chapter 10

PowerPoint Presentation for Dennis, Wixom & Tegardem Systems Analysis and Design
Slide 2
Key Definitions
The system architecture design consists
of plans for the hardware, software,
communications, security , and global
support for the new application
The designers must decide if processing
will occur in the server (server-based), at
the personal computer (client-based), or
in some combination of these (client-
server based).

Slide 3
Key Definitions
The network model shows major
components of the system, where
they are located and how they will
be connected to one another.
The hardware and software
specifications describe these
components in detail and aid those
responsible for purchase and
acquisition of these products.

Slide 4
COMPUTING
ARCHITECTURES

Slide 5
Functions of the
Application System
Data storage
Data access logic
Application logic
Presentation logic

Slide 6
Architectures
Server based
Client based
Client-server based

Slide 7
Alternative Servers
In server based architectures,
the servers do the work and
present the results
Mainframe
Minicomputer
Microcomputer (personal
computer)

Slide 8
Server-Based Computing

Slide 9
Alternative Clients
In client based architectures, clients
do most of the work (except data
storage) and present the results
Terminals
Microcomputer (personal computer)
Special purpose terminals
(ATMs, kiosks, Palm Pilots,
and many others)

Slide 10
Client-Based Computing

Slide 11
Client-Server-Based
Computing (2 Tiers)

Slide 12
Client-Server Attributes
Typical Pros
Compatible with
web-based system
design
Scaleable
Work with multiple
vendors/products
No central point of
failure
Typical
Cons/Limits
Complexity
New programming
languages and
techniques (stress
for personnel)
More complex to
update

Slide 13
Client-Server -- Three
Tiers

Slide 14
Client-Server -- Four Tiers

Slide 15
N-Tiered Client-Server
Attributes
Typical Pros
Separates
processing to
better balance
load
More scaleable
Typical
Cons/Limits
Greater load on
the network
More difficult to
program and
test

Slide 16
Distributed Objects
Computing
Middleware between clients and
servers
Update middleware when changing
client code
May reduce efficiency of the
application
CORBA
DCOM

Slide 17
Realities of Infrastructure
Design
Most often the infrastructure
will be in place
Coordination of infrastructure
components is very complex
The application developer will
need to coordinate with
infrastructure specialists

Slide 18
Selecting a Computing
Architecture
Server-Based Client-based Client-server
Cost of infrastructure Very high Medium Low
Cost of development Medium Low High
Ease of development Low High Low-medium
Interface capabilities Low High High
Control and security High Low Medium
Scalability Low Medium High

Slide 19
Your Turn
Consider the course registration
system at your university:
What computing architecture does it
use?
What computing architecture would
you use if you were replacing it
today?

Slide 20
INFRASTUCTURE
DESIGN

Slide 21
The Network Model
No standard format
Conveys complexity of the system
and how components fit together
Components are
Clients
Equipment
Connection to external systems or
networks

Slide 22
Top-Level Network Model

Slide 23
Hardware and Software
Specification
Used if new hardware or
software must be purchased
Actual acquisition of hardware
and software usually left to a
purchasing department --
especially in larger firms

Slide 24
Steps in Hardware and
Software Specification
Note hardware in low-level network
model to create list of needed hardware
Describe equipment in as much detail as
possible
Consider whether increased processing
and traffic will absorb unused hardware
capacity
Note all software running on each
hardware component

Slide 25
GLOBAL ISSUES

Slide 26
Global Requirements
Multilingual requirements
Concurrent multilingual systems
Discrete multilingual systems
Local versus centralized control
Unstated norms (e.g. dates,
currency)
24-7 Support
Communications infrastructure

Slide 27
SECURITY

Slide 28
Identifying Threats to the
System
A threat is any potential adverse
occurrence that can do harm to the
application or its data
Threats come from internal as well
as external sources
Categories of threats
Disruptions, destruction and disaster
Unauthorized access

Slide 29
Most Common Threats

Slide 30
Assessing the Risk of Each
Threat

Slide 31
Creating Controls
A control is something that
mitigates or stops a threat
Controls include
redundancy
fault tolerant servers
disaster recovery plans
anti-virus software

Slide 32
Additional Controls
Include
A security policy
Passwords and encryption
Firewalls

What sort of computer
architecture would you
recommend for CD Solutions?
Explain your preference.

Slide 34
Summary
The three fundamental computing
architectures are server-based, client-based,
and client-server based.
The network model shows technical
components of the system and their
geographic location throughout the
organization.
Hardware and software must be specified for
acquisition in the project
The systems analyst needs to also account
for global issues and security measures.

Slide 35
Expanding the Domain
To contrast the approaches of
CORBA and DCOM/COM from
Microsoft, check the following
websites:
http://www.corba.org
http://www.microsoft.com/com

system architecture.ppt

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