Multi-Party XML Synchronization over Limited Bandwidth Thomas Wilczak Prof. James Riely SE 696 Research Project Initial Presentation 5th May, 2004

5/7/20042 Motivating Examples Distributed Inventory Management Central inventory stored as XML database Updates performed by employees using mobile devices while verifying actual product details

5/7/20043 Motivating Examples Distributed Inventory Management: Characteristics Central data tree Segmentation of data Independent updates

5/7/20044 Motivating Examples Field Reconnaissance Central XML database containing information about field conditions Clients require current information about field conditions Clients performing updates to allow real-time decision-making

5/7/20045 Motivating Examples Field Reconnaissance: Characteristics Clients require rapid access to most recent updates Central data tree needs coherent updates from clients

5/7/20046 General Problem: Tree Synchronization Current Approaches Synchronization File Synchronization - rsync Source Synchronization - CVS XML Merge - Delta XML Abstraction Bi-Directional Language for Tree Transformation - Lenses

5/7/20047 Requirements Central data server Tree Structured data Clients running on limited devices Read access to data through clients Write access to tree subsets Handling transactions between clients and server smoothly and concurrently

5/7/20048 Synchronization Model Components 1.Abstraction Model: responsible for moving data set from the server to the clients 2.Server side exclusion mechanism: Prevents write- write conflicts when updates are sent from the client to the server 3.Client side command logging: modifications made to the client’s data recorded 4.Abstract series of commands sent back to server. Subset updated, synchronization performed

5/7/20049 Deliverables Simulation of Client and Server running in single JVM Server  Handles reading, storing, and abstraction of data for use by clients.  Maintains consistency of data by preventing conflicts.  Reconcile Data changes as they are returned from the client. Client  GUI allowing user to read and modify local data subset  Logs abstract commands performed on local subset Proof of correctness (?) - possibilty for publication

5/7/ Project Outline: Milestones  Phase 1: Literature Review 11/ /2004 "What is a File Synchronizer?", S. Balasubrmaniam, B.C. Pierce "A Language For Bi-Directional Tree Transformations", Michael B. Greenwald, et al. “SyncML Sync Protocol, version 1.1”, SyncML Group “Merging XML Changes with DeltaXML”, Monsell EDM Ltd  Phase 2: Project Definition 1/ /2004 Discussion and review of previous work Specification of approach and research objectives Initial implementation of Synchronization Infrastructure in ML Translation of initial implementation into Java  Phase 3: Initial Presentation 5/7/2004  Phase 5: Ongoing Development 5/ /2004  Phase 6: Intermediate Presentation 9/2004  Completion: 11/2004

5/7/ References "What is a File Synchronizer?", S. Balasubrmaniam, B.C. Pierce "A Language For Bi-Directional Tree Transformations", Michael B. Greenwald, et al. “SyncML Sync Protocol, version 1.1”, SyncML Group “Merging XML Changes with DeltaXML”, Monsell EDM Ltd