networked database applications and reengineering copyright 1996 prentice-hall
TRANSCRIPT
Networked Database Applicationsand Reengineering
Copyright 1996 Prentice-Hall
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Client/Server Database
Client Database Program(Excel)
Server Database Program(Oracle)
Application Request Message
Application Response Message
Network or Internet
Platform IndependentThanks to TCP
Client, server can beany type of machine
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Access to Multiple Databases
ClientProgram
ClientProgram
Database Program XServer 1
Database Program XServer 1
Database Program ZServer 4
Database Program ZServer 4
Database Program WServer 6
Database Program WServer 6
IntegratedReport
IntegratedReport
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Incremental Database Development
ServerDatabaseProgram
ServerDatabaseProgram
1Data Entry Program
1Data Entry Program
2Credit Checking Program
2Credit Checking Program
3Management Statistics
Program
3Management Statistics
Program
4Etc.
4Etc.
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ODBC: An Application Layer Protocol
Open Database Connectivity (Microsoft standard) Microsoft now pushing OLE
Client Program(Application)
Client Program(Application)
Transport LayerTransport Layer
Internet LayerInternet Layer
Subnet LayerSubnet Layer
Client Machine
Server Database Program(Application)
Server Database Program(Application)
Transport LayerTransport Layer
Internet LayerInternet Layer
Subnet LayerSubnet Layer
Server Machine
ODBC
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Database Middleware
Problem: Incompatible database applications
– New systems that follow different standards
– Old (Legacy) systems that must be maintained
One solution
– Database middleware
– Layer below application layer
– Handles lower-layer details for application program
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Database Middleware
IncompatibleServer
Program
IncompatibleServer
Program
DatabaseMiddleware
Program
DatabaseMiddleware
Program
TransportInternetSubnet
TransportInternetSubnet
Physical Layer Connection
ClientProgram
ClientProgram
DatabaseMiddleware
Program
DatabaseMiddleware
Program
TransportInternetSubnet
TransportInternetSubnet
IncompatibleLegacy
Program
IncompatibleLegacy
Program
DatabaseMiddleware
Program
DatabaseMiddleware
Program
TransportInternetSubnet
TransportInternetSubnet
RequestResponse
FileTransfer
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Data Warehouse
Problem: Users need data from multiple databases
– They need to integrate these data
– Different databases have different access methods
– Queries to operational databases would cause performance problems for operational use
– Queries to operational databases could cause security problems
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Data Warehouse Solution
– Extract data to a “data warehouse”– Clean up the data– Give users access and analysis tools
DataWarehouse
DataWarehouse
ClientProgram
ClientProgram
InventoryDatabase
InventoryDatabase
SalesDatabase
SalesDatabase
PlanningDatabase
PlanningDatabase
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Data Warehouse Tools
Multidimensional databases
– Can search easily by region, product, salesperson, etc.
Online Analytical Processing (OLAP)
– Special tools for analyzing data from databases
– Forecasts, etc.
Data Marts
– Limited data warehouses for departments, other groups
– Much easier to set up, rapid payback
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Data Marts
Large data warehouses are difficult to create and manage
Data marts offer similar services for smaller groups, such as departments
Simpler, easier to develop
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Tiers
Two-Tier Processing
– Server handles database access
– Client handles user interface
– Client may have to handle extensive calculation based on business rules. (“Extend credit if the following 20 conditions are met.)
– Business rules processing can result in “fat clients” with the power normally required for servers
Fat Client
DatabaseServer
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Three-Tier Processing
Client only handles user interface: Thin client
Business rules server handles complex calculations
Database server: Retrieves appropriate data
ThinClient
DatabaseServer
Business Rules Server
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On the World Wide Web Client fills out form in browser program on PC
– Passes form to webserver
Form
Browser Webserver
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On the World Wide Web Webserver receives the form
– Passes request to a database access program
Browser WebserverDatabase
Access Program
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On the World Wide Web Database access program formulates request
– Sends to database program
DatabaseAccess Program
DatabaseProgram
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On the World Wide Web Database program retrieves data
– Passes to the database access program
DatabaseAccess Program
DatabaseProgram
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On the World Wide Web Database Access Program Puts Answer in Webpage
– Passes page to the server, which passes it to browser
Browser WebserverDatabase
Access Program
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On the World Wide Web Interactions between the webserver and the database must
be standardized
CGI
– Common Gateway Interface is the oldest standard
– Standardizes ways of passing data values to DBMS
– Standardizes ways of receiving results from DBMS, sending as webpages
– Slow: each interaction restarts the DBMS program, unless proprietary APIs are used
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On the World Wide Web Interactions between the webserver and the database must
be standardized
APIs
– Application Program Interface
– Standardized way for any application program, including webservers, to send calls to DBMSs, get responses
– High-performance
– Different DBMSs have different APIs
– Most webservers support only some DBMS APIs
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Distributed Databases
Form 1
Form 2
Update
Update
Replicate
Replicate
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Distributed Databases
Store data near users for rapid response
Safety in case of a site disaster
Replication
– Propagating changes to appropriate databases
– Often must be done in real time
– Otherwise, two travel agents would sell the same airline seat
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Multimedia Databases
Graphics, sound, even video
Telephone Directory
Last name: Lee
First name: Pat
Extension: x6894
Pat’sphotowill gohere.
Pat’sphotowill gohere.
Click to hear Pat’sRecorded Greeting
Click to hear Pat’sRecorded Greeting
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Commercial Online Services
Provide For-Fee Information Usually Internet access too
(new)
UserPC &
Modem
UserPC &
Modem
CommercialOnlineService
CommercialOnlineService
WANWAN
Internal Services:Information
CommunicationProcessing
Internal Services:Information
CommunicationProcessing
The InternetThe Internet
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Commercial Online Services
Consumer-Oriented Services
– Focus on residential users
– Widely touted in the media
– America Online, CompuServe, Microsoft Network
– Small part of online services business
– Internet makes their future uncertain
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Commercial Online Services
Business Processing Services
– Payroll
– Insurance claims clearing houses, etc.
– Very large
Business Information Services
– Credit checking, etc.
– Corporate financial information
– Very large
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Commercial Online Services
Electronic Data Interchange (EDI)
– Business exchange high-volume business documents
– Invoices
– Orders, etc.
– Still rather small
Electronic Funds Transfer (EFT)
– Send money electronically
– Very large intra-bank systems
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Reengineering
If you simply automate what you are doing now, gains will be very small
To get large gains
– Find a more efficient way to do the end goal
– You need a new strategy
– Use information technology (if needed) to get you there
– Good implementation is critical
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Reengineering
Importance of IT
– Removes old limitations that forced us to work certain ways
– But only those who can grasp new possible strategies will benefit
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Obliterate Work
Work is caused by business rules
– Suppliers must furnish us with invoices
Drop rules if they no longer make sense– Ford Motor Company
– Suppliers now delivery goods without invoices
– Ford reads the Universal Product Code on boxes
– Ford pays automatically
– Slashed accounts payable department
– The best way to massive gains
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Consolidate Work
Bad for work to send job from one department to another in sequence
– In each department, waits in line for processing
– Long delays in processing
– High cost because many people are involved
Why send work between departments?
– Before, each department had needed information in its paper files and in the heads of people
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Consolidate Work
Today
– Any employee can get data from distant databases
– No need to ship work between departments
Case worker
– Does whole task previously done by many
– Like airlines reservations clerk
Case teams
– Where individual workers cannot do the job alone
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Teams
Form teams only as needed
Get right mix of people for the job
Disband the team afterward
Companies may consist mostly of such teams
– Ad hocracies
Virtual corporations
– Membership may include people outside the firm
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Interorganizational Systems
Vertical Cooperation
– Manufacturer, wholesalers, or retailers may cooperate
– Traditionally called the marketing system
– Supplier sends goods just in time by reading buyer’s internal database system
– Creates new relationships: partnerships
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Interorganizational Systems
Horizontal Cooperation
– Firms that are competitors band together to offer a service
– Banking ATM networks
– Again, new relationships
Difficult because of natural competitiveness
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Outsourcing
Decide on a firm’s core business processes
– Provide firm’s sustainable competitive advantage
Outsource other (non-core) business processes to another firm
– Manage on a contractual basis
Outsourcing firms should be less expensive
– Specialization should bring economies of scale
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New Channels
Internet allows us to reach world-wide audiences– Very large audiences for massive sales
– Specialized audiences reached no other way
The Internet– Sell less expensively
– Provide more data to customers
– Route customer questions to experts
– Eliminate the cost and stocking time required for traditional retailing
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Telecommuting
Spending some or all of the workday away from the office
Reduces commuting time and road congestion
Can provide satisfaction to telecommuters, enhancing retention
But managers spend 85% of the day communicating, 55% face-to-face.
– Will coordination be harmed?
How can teleworkers be managed, assessed?