Transcript Migrating From Relational To Object

Migrating From Relational To
Object-Oriented Databases
Masood Asif, Kenny Dunlop,
Gerard Given & Grant Stalker
Structure Of Talk
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Grant
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Abstract
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Introduction
 What are Relational Databases?
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Pro’s & Cons of Relational Databases
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What are Object Oriented Databases?
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Pro’s and Cons of Object Oriented Databases
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What is MIGRATION
 Pro’s and Cons of migration
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Architecture
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Example
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Conclusion
Structure Of Talk
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Gerry
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Routes For Migration
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Cold Turkey
Chicken Little
Dead & Alive Parallel Approach
Recovery /Step Back
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Cold Turkey
Chicken Little
Dead & Alive Parallel Approach
Introduction
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Who Wants to MIGRATE to an OODB from
Relational Databases?
What Is a Relational Database?
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What is the standard user application program
interface to a relational database?
Pro’s & Cons Of Relational
DB
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Pro’s
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Very simple to understand and implement
Well documented
Many proven vendor solutions available
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Easy to modify existing databases
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Con’s
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Very little flexibility for data structuring
Current query language is not computationally complete
Little or no support for temporal data
They cannot sufficiently express data that does map well to tables
The new query language (SQL3) is far too complex
Object Oriented Databases
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What type of uses have OODB have in
organisations?
Definition of an OODBS
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An Object Oriented Database must
satisfy 2 criteria:
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Should be a DBMS
 DBMS Translates into 5 features
Should Be an object oriented system i.e. to
extent possible should be consistent with
the current crop of object oriented
programming languages
 OOS Translates into 7 features
Pro’ & Cons of OODB
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Pros (Object Oriented)
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Model real-world environment effectively
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Objects encapsulates both state and behavior allowing for code
reuse
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Organization of data can be done by the needs of the application
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OO Programming languages provide faster development e.g.
Applications.
Cons (Object Oriented)
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Many vendors in the market but which ones will survive to provide
support
Migration
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What Is Migration?
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What are the cons for migration?
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What are the Pro’s for migration?
Architecture
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There are two Types of Legacy
Architecture
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Legacy Relational Databases
(Decomposable Legacy IS)
Legacy Non-Relational Database (NonDecomposable Legacy IS)
Why are Legacy Relational Databases
easier to migrate than Non-Relational
Databases?
Diagram Example
GUI I
GUI
Interface
Application
Modules
Interface
Application
Modules
Legacy Relational Database
Decomposable Legacy I.S.
Data
Legacy Non Relational Database
Non-Decomposable Legacy I.S.
Data
Structure Of Talk
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Gerry
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Routes For Migration
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Cold Turkey
Chicken Little
Dead & Alive Parallel Approach
Recovery /Step Back
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Cold Turkey
Chicken Little
Dead & Alive Parallel Approach
Routes For Migration
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Routes
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Cold Turkey
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What is cold turkey?
Issues With Cold Turkey
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Lack Documentation
Application Dependencies
Project Management
Time Doesn’t Stand Still
New Functionality
Live Data
Company Reorganisation
Savings
Routes For Migration
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Chicken Little
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About Chicken Little
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Main Issues
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Step By Step
Gateways
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Use of Gateways
Example of a Gateway
Legacy GUI
(Live)
Target New GUI
(Not live yet)
Gateway
Target I.S.
(OODB)
Data
Dead & Alive Parallel Approach
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What is Dead & Alive Parallel Approach?
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Time Scales
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Requires More Resources
Recovery/Step Back
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What happens in the discussed
strategies in the event of an error or
mistake?
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Cold Turkey
Chicken Little
Dead & Alive Parallel Approach
Conclusion
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Is there a definite answer, should a
company migrate to an OODB or not?