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Design and Implementation of a Module to Synchronize Databases

Design and Implementation of a Module to Synchronize Databases. Amit Hingher Reviewers: Prof. Dr. rer. nat. habil. Andreas Heuer Prof. Dr.-Ing. Hartmut Pfüller Advisor : Dr.-Ing. Holger Meyer Herr Andreas Finger Stefan Dummann (softEnergy GmbH) .

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Design and Implementation of a Module to Synchronize Databases

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  1. Design and Implementation of a Module to Synchronize Databases Amit Hingher Reviewers:Prof. Dr. rer. nat. habil. Andreas Heuer Prof. Dr.-Ing. Hartmut Pfüller Advisor: Dr.-Ing. Holger Meyer Herr Andreas Finger Stefan Dummann (softEnergy GmbH) Master Thesis, University Of Rostock, Germany 23rd May 2007

  2. Overview • Introduction • Concept • WIS-Sync - A Prototype • Conclusions & Future Work Master Thesis, Amit Hingher

  3. 1. Introduction • Data Replication • Wind Information System (WIS) • Motivation • Existing Solution Master Thesis, Amit Hingher

  4. What is Data Replication? • Database replication: • Process of creating and storing multiple copies of a database with the same data in different locations. • Two types of replication- • Synchronous • Asynchronous Master Thesis, Amit Hingher

  5. Data Synchronization • Synchronization / Merge replication • Keeps the data in two or more locations up-to-date so that each repository contains identical information. • Copies data in both directions • Used for disconnected environment Master Thesis, Amit Hingher

  6. WIS - Wind Information System • An innovative solution for complex analyses and monitoring of power plant data received from energy plants • GUI is provided by a Web server and can be accessed by client through a Web-Browser like IE or Mozilla • Diverse databases running on the server and client i.e. Oracle, Sybase, MySQL • Communication only possible between server and remote replicas and no “inter-replica” communication Master Thesis, Amit Hingher

  7. Motivation WIS Synchronize Local copy Server No communication link Local copy Master Thesis, Amit Hingher

  8. System Overview Master Thesis, Amit Hingher

  9. Existing Solution WIS Master Thesis, Amit Hingher

  10. Why another solution ? • Dumping whole DB to client • Alternative to log based capture – • A middle-ware replication tool that intercepts command stream between application and database • Synchronization tool relies entirely on transaction log • Cost of maintenance • Currently no manual interaction Master Thesis, Amit Hingher

  11. 2. Concept • Proposed System • WIS-Sync: A 3-Step Process • Capture process • Merge Process - Conflict Resolution • Table Filtering • Incremental progress • Manual resolution Master Thesis, Amit Hingher

  12. WIS-Sync: A 3-Step Process Master Thesis, Amit Hingher

  13. Golding’s Timestamp Anti-Entropy Protocol • Updates are propagated via anti-entropy sessions in which two replicas exchange the content of their logs Master Thesis, Amit Hingher

  14. WIS-Sync: Capture Process Master Thesis, Amit Hingher

  15. Conflict Resolution - Basics • A conflict is said to arise when rows with same unique ID from the same tables are updated on different databases • Resolution option used: • Server- Wins • Client-Wins Master Thesis, Amit Hingher

  16. Conflict Scenario - 1 • Insert – Insert Master Thesis, Amit Hingher

  17. Conflict Scenario - 2 • Update - Delete Master Thesis, Amit Hingher

  18. Conflict Scenario - 3 • Update-Update Master Thesis, Amit Hingher

  19. WIS-Sync: Merge Process Master Thesis, Amit Hingher

  20. Table-Filtering • Allows user to select the tables he wants to synchronize • Provides maximum flexibility • User has full control over the system thus avoiding any unnecessary updates Master Thesis, Amit Hingher

  21. Incremental Progress Master Thesis, Amit Hingher

  22. Violations – An Example Master Thesis, Amit Hingher

  23. How has this research helped ? • Features & Improvements • Capture Process - “direct-to-database” method • Table filtering • Conflict Resolution • Incremental progress • Manual resolution • Support for heterogeneous databases Master Thesis, Amit Hingher

  24. 3. WIS-Sync : A Prototype Master Thesis, Amit Hingher

  25. OJB – ObJect Relational Bridge • Apache (OJB) is an Object/Relational mapping tool that allows transparent persistence for Java Objects against relational databases. • Supports the following DB’s: • MSSQL • MySQL • Oracle • MS Access • PostgreSQL • Informix • Sybase • MaxDB Master Thesis, Amit Hingher

  26. O/R Mapping Master Thesis, Amit Hingher

  27. WIS-Sync: Class Diagram Master Thesis, Amit Hingher

  28. WIS-Sync: Configuration Page Master Thesis, Amit Hingher

  29. 3. Conclusions • No general solution available toward synchronization • Principal goal of an update propagation strategy is to ensure internal and mutual consistency • “Direct-to-database” approach can prove to be an alternative to log-based capture • O/R Mapping can be used in scenarios where compatibility between diverse databases is needed. Master Thesis, Amit Hingher

  30. Future Work • User-friendly GUI Interface • Multiple users synchronizing • Could be implemented for a mobile as well. Master Thesis, Amit Hingher

  31. Thank you all !!! Master Thesis, Amit Hingher

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