Migrating From Relational To Object-Oriented Databases Masood Asif, Kenny Dunlop, Gerard Given & Grant Stalker

Structure Of Talk Grant Abstract Introduction What are Relational Databases? Pro’s & Cons of Relational Databases What are Object Oriented Databases? Pro’s and Cons of Object Oriented Databases What is MIGRATION Pro’s and Cons of migration Architecture Example Conclusion

Structure Of Talk Gerry Routes For Migration Cold Turkey Chicken Little Dead & Alive Parallel Approach Recovery /Step Back Cold Turkey Chicken Little Dead & Alive Parallel Approach

Introduction Who Wants to MIGRATE to an OODB from Relational Databases? What Is a Relational Database? What is the standard user application program interface to a relational database?

Pro’s & Cons Of Relational DB Pro’s Very simple to understand and implement Well documented Many proven vendor solutions available Easy to modify existing databases Con’s 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 What type of uses have OODB have in organisations?

Definition of an OODBS An Object Oriented Database must satisfy 2 criteria: 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 Pros (Object Oriented) Model real-world environment effectively Objects encapsulates both state and behavior allowing for code reuse Organization of data can be done by the needs of the application OO Programming languages provide faster development e.g. Applications. Cons (Object Oriented) Many vendors in the market but which ones will survive to provide support

Migration What Is Migration? What are the cons for migration? What are the Pro’s for migration?

Architecture There are two Types of Legacy Architecture Legacy Relational Databases (Decomposable Legacy IS) Legacy Non-Relational Database (Non- Decomposable Legacy IS) Why are Legacy Relational Databases easier to migrate than Non-Relational Databases?

Diagram Example Legacy Relational Database Decomposable Legacy I.S. Data Legacy Non Relational Database Non-Decomposable Legacy I.S. Data Application Modules Application Modules GUI I Interface GUI

Structure Of Talk Gerry Routes For Migration Cold Turkey Chicken Little Dead & Alive Parallel Approach Recovery /Step Back Cold Turkey Chicken Little Dead & Alive Parallel Approach

Routes For Migration Routes Cold Turkey What is cold turkey? Issues With Cold Turkey Lack Documentation Application Dependencies Project Management Time Doesn’t Stand Still New Functionality Live Data Company Reorganisation Savings

Routes For Migration Chicken Little About Chicken Little Main Issues Step By Step Gateways Use of Gateways

Example of a Gateway Target I.S. (OODB) Gateway Data Legacy GUI (Live) Target New GUI (Not live yet)

Dead & Alive Parallel Approach What is Dead & Alive Parallel Approach? Time Scales Requires More Resources

Recovery/Step Back What happens in the discussed strategies in the event of an error or mistake? Cold Turkey Chicken Little Dead & Alive Parallel Approach

Conclusion Is there a definite answer, should a company migrate to an OODB or not?