Transcript Systems Support to Distributing Business

Asper School of Business - MBA Program
6150 Management of Information Systems & Technology
April-June 2009
Instructor: Bob Travica
Class 7
Distributing Business and Systems
Updated May 2009
Outline
• Strategies of Distributing Business & Systems
• Concept of Distributed Systems
• Client-Server Architecture
• Messages for change leadership
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Strategies of Distributing Business & Systems
• Organizations dispersed in space (individuals, groups, units;
e.g., salespeople in master case)
• Dispersed org. entities can have different information needs –
low
Spatial dispersion
high
•
Information systems have to support different strategies of
distributing business
•
Inter-cultural aspect (master case)
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Distributed Systems Concept: What Can Be Distributed
• An aspect of systems architecture (overall design of computing
resources).
Information System Parts
(resources, services)
User Interface
(Presentation,
input/output screens)
Data
(Data mgmt,
Database)
Application
Software
(Functionality,
Data processing)
• Any of these parts can be distributed – data, functionality,
user interface. If all run by one computer, the system is
centralized.
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Distributed Systems: Data View
• Rule #1 for distributed systems: Make data available where
users need them.
• Method 1: Central store, distributed access. Role of networks
(3i, Northwest Airlines).
• Method 2: Partition data store. Data fed and searched locally;
occasional cross search.
Purchasing
Toronto
Production
Winnipeg
Sales
Vancouver
More
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• Method 3: Data partitions stored locally in real time, and
partitions replicated across locations in certain intervals.
Purchasing
Production
Sales
Toronto
Purchasing
Production
Sales
Purchasing
Production
Sales
Vancouver
Winnipeg
• Golden rule: Regardless of the specific architecture,
users should not care if a system is distributed and in
what manner. Access should be seamless.
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Distributed Systems Continuum
• Data processing, data storage, user interface – a continuum
showing levels of distribution of system parts in an enterprise:
Mainframe with
dumb terminals
in departments
Centralized
Client-Server
Systems in/across
departments
Departmental
stand-alone systems
Decentralized
• Computer networks – key role in distributed systems.
Networks are part of IT Infrastructure (foundational systems
serving entire enterprise).
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Client-Server (C/S) Architecture
•
Most frequent today
• C/S systems distribute data, functionality or both
between a machine that requests a service (client)
and a machine that provides a service (server).
Client
Request
Server
Service
•
Division of responsibilities for data and functions,
user interface usually on the client.
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Models of Client-Server Architecture
• Models of C/S architecture determined by different patterns of
sharing responsibility for data, functionality, and user interface
between computers.
• Shared Processing (both server and client have certain functionality;
LAN w/ database server, Internet models – applets, Web services)
Database
Sever
- Database (data)
- Query and Report
processing
…
Report creation
Request
Report
Data lookup,
input
Data table
transfer
Client
- Input/Output screens
- Query and Report
code
More
Note: Server is software, but it usually runs on a dedicated computer.
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• Variant of Shared Processing with middleware
Middleware
(Code defining rules of
business*;
translation software)
Database Server
(Databases can be on a
mainframe - “legacy system”)
Client
(Application
software)
• * Example from HR domain: An employee is defined by an employee number, name,
job position…, is associated with 1 department, reports to 1 manager, cannot have $0
salary, can have different benefit packages over time, etc.
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• Variant of Shared Processing via the Internet (applets; Web services)
Web page
Application
Web
Server
Server Request
translated
Mortgage Info
Request
Client
Web page with cust.
data + applet
- Upon getting
data & applet, runs
if-then calculations
Customer
Data +
Mortgage Applet
Database
Server
Other systems
Internet
• Case: Chubb & Son
• Cases: SABRE
More
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Messages for Change Leadership
• If business is to get distributed,
determine how can IS support this strategy.
• Beware that data must be available where users need them,
and that users should not worry whether the system
is distributed or not.
• Be sensitive to company’s culture regarding its readiness for
distributed systems (trust issues).
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