Transcript CHAPTER 10
CHAPTER 9
Application Architecture
Objectives
List
main issues that a SA should consider when
an application architecture
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Enterprise resource planning
Initial costs
TCO
Scalability
Web integration
Legacy requirements
Security
Processing options
Objectives
Describe
servers, server and client based
processing
Explain client/server architecture
Client/server tiers, cost-benefit issues
Explain impact of Internet
Describe online and batch processing
Define network topology
Objectives
Explain
network protocols and licensing
issues
Describe tools for modeling application
architecture
Explain system management tools
Describe system design specifications
Application Architecture
Application
requires hardware, software,
data, procedures, people to accomplish
organized set of functions
Effective system combines those elements
into an architecture – design– that is
flexible, cost-effective, technically sound,
and able to support information needs of the
business
Application Architecture
Translates
logical design of an information
system into a physical structure that
includes hardware, software, network
support, and processing methods
Design Checklist
Enterprise
resource planning
Initial cost and TCO
Scalability
Web Integration
Legacy interface requirements
Security
Processing options
Enterprise Resource Planning
Defines
a specific architecture, including
standards for data, processing, network and user
interface design
Describes specific environment (platform) is
the combination of hardware and systems
software used for the developed information
system
– Ensures hardware connectivity and easy integration
of future applications, including in-house and
commercial packages
Initial Cost and TCO
Review
options to determine if outcome
may be affected by new developments.
Scalability
Measure
of system’s ability to expand,
change, or downsize easily to meet
changing needs.
– Can drastically affect system’s life expectancy
Web Integration
Part
of e-commerce????
Intranet based????
Legacy
older
systems that typically run on
mainframe computers (architecture)
– Interface with legacy systems
How
will new system communicate?
Security
Physical
and logical security
Web-based security
Processing Options
High
capacity transaction processing system
(eg. order entry) requires more network ,
processing and data storage resources -- 24/7
– Must consider backup and recovery procedures
System
updates, file maintenance and other
batch processing – done off-peak – lower costs
and resources
Planning the Architecture
– a computer that supplies data,
processing services, or other support to one
or more computers (client)
Client – a computer that is connected to a
server
Mainframe architecture -- server performs
all the processing
Server
Planning the Architecture
Processing
performed on a server
Processing performed on a client
Processing divided between server and
client
We
must plan (advantages and
disadvantages) of each design approach
Planning the Architecture - Mainframe
Server-based
processing – relies on network
technology
Centralized design – remote user keystrokes
transmitted to mainframe – responds by sending
screen output back to user terminal
Advantage – various types of terminals can
communicate with mainframe and mainframe does
all the work
Disadvantage – character-based terminals – no GUI
All data storage, access, and application programs
on mainframe
Planning the Architecture
Clients
Stand-alone
LAN
WAN
computing
Client/Server Architecture
Systems
that divide processing between one
or more networked clients and a central
server
– Client handles user interface, data entry, data
query, and screen presentation
– Server stores data and provides data access and
management functions
Client/Server --- Mainframe
Fat Client --- Thin Client
Client / Server Architecture
Client
/ Server Tiers
Cost-Benefit Issues
Performance Issues
Processing Methods
Online
vs. Batch Processing
On-line processing
System
in which transactions are
processed when and where they
occur, allows output directly to end
users
–also called online transaction
processing or interactive
processing
On-line processing
workstation
-- either a PC or
terminal connected to online
processing system
–online processing system verifies
the transaction values and allows
end user to interactively enter
data and correct errors
On-line processing
Online
file -- data file with direct or
indexed organization that allows
random access
– sequential files not used for online
processing
IS
must be continuously available whenever
end users require processing of transactions
Batch Processing
IS
in which data is collected and,
at some later time, all the data that
has been gathered is processed as a
group, or batch
Used extensively in 1950’s-60’s
Still used today for many
applications
Batch Processing
Any
application that requires
periodic processing of a large
number of records is good
candidate for batch processing
– payroll
– billing/invoicing
– hard copy reports
Today’s processing trends
Online
and batch processing
combined in single IS
– random access files are available for
transactions that require interaction
– actual files available off-line for large
batch processing
– copies of online files available for
batch reports that don’t require update
Online vs. Batch
Online Advantages
– data is entered and validated as it
occurs
– data is available sooner in more
accurate form
– data is up-to-date
Online vs. Batch
Online
Disadvantages
– more expensive/difficult to maintain
– creation is more difficult
– more sophisticated hardware
– backup and recovery more difficult
– effects of computer failure more
disruptive
NETWORK
Data
communications network
collection of terminals,
computers, and other equipment
that use communication
channels to share data,
hardware and software
Network Topology
Four
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patterns:
Hierarchical
Bus
Star
Ring
Network Topology --
Network Topology --
Network Topology --
Network Topology --
System Architecture
Network
Protocols
Licensing issues
Performance Management
Designed
to collect information about
system resources and activity levels.
– System usage
– Capacity
– Trends
Fault Management, Backup and
Disaster Recovery
RAID
Online
Disaster Backup and Recovery plans
Batching processing Backup and Recovery
plans
System Design Completion
Software
Design Stages:
– System Analysis phase: functional primitives
were identified and documented
– System Implementation phase: Programmers
determine exactly how each program will
accomplish its objectives.
System Design
Final
activities:
– System Design Specification
– Obtaining user approval
– Delivering presentation to Management
System Design Specification
Management
Summary
System Components Details
Environmental Requirements
Implementation Requirements
Time and Cost Estimates
Appendices