Designing For Occasionally Connected Apps Slideshare
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The document discusses local database caching using the Microsoft Sync Framework, highlighting its application, functionality, and implementation steps for synchronizing data across various platforms. It includes a case study of challenges encountered during a presentation preparation, along with troubleshooting tips, conflict resolution methods, and demo project details. Lastly, it provides additional resources and contact information for further inquiries.
Designing For Occasionally Connected Apps Slideshare
- 1. Local Database Caching with the Microsoft Sync Framework presented to NUFWon 11/10/2009 DESIGNING APPLICATIONS FOR THE OCCASIONALLY CONNECTED SCENARIO
- 2. About Me Work for Systemental, Inc as a Consultant and Software Developer Software development to support Corporate business process improvement since 2000 (Lean or Continuous Improvement Initiatives) .Net since 2004 President, fwPASS.org Mfg. Eng. Technology degrees from Ball State University
- 3. A case study in failure What could go wrong preparing this presentation did Initial demo worked in minutes (after about three minor problems) SQL CE debugging challenges 1. Refactor - created numerous problems 2. Test - find problems requiring schema changes 3. Repeat 1-2 ad nauseum
- 4. What we will cover What is the Microsoft Sync Framework? How you can use it? Why? How does it work? How do you implement it? Demo’s Gotcha’s, gotcha’s, and debugging
- 5. What is the Sync Framework Provider-based API for synchronizing data or files across multiple applications, services, and physical devices Included providers Database * File system Web – RSS/Atom
- 6. How can it be used? Server to Local Local to Server Bi-directional
- 7. Why? Why not pub/sub, log shipping, replication? Reliability Purpose schedule granularity Disconnected, hello…. Argument: Internet is everywhere and growing CE vs. Express Encrypt or password protect the file Document-safe, no code stored in file Light 1.8Mb vs. 58Mb
- 8. How does it work? Visual Studio local database cache template Schema changes (couple fields and tombstone) Triggers or 2008 Change data capture
- 9. Sync Process
- 10. Steps to Implement Add new item - local database cache Create database/tables to sync or modify DDL Sync Configuration wizard Configure source/target databases add/edit .sdf database add sync tables Generate/run scripts to adjust ddl/sync Generate typed dataset/table adapters (optional) Generate Linq2SQL or EF classes (optional) Set sync direction and .Synchronize
- 11. Demo project
- 13. Demo project details WPF application with a single keystroke input F5 key Changing background color (green, yellow, red) based on actual count vs. target count Two dispatcher timers: 1. Screen display color update (every second) 2. Db synchronization (every minute) WinForm SQL CE cache table viewer Using Repository pattern and Linq to SQL
- 14. Demos Existing SQL db, switch to CE 3.5 using provider and connection string change Wizardry SQLMetal Profiler Server to local sync (default) local to server sync/bi-directional (code- behind)
- 15. SQLMetal to create Linq2SQL classes
- 16. Gotcha’s Visual Studio Linq2SQL template doesn’t support SQL CE provider – use SQLMetal to generate, then include in project LINQ dbml created from MSSQL, not compatible CE SSMS 2005 would not open a CE 3.5 .sdf file. Need SSMS 2008 Set sync direction if anything other than server to local Changing schema’s after generation – remove everything and start over (use sql scripts to roll back) Insert/Update triggers not auto created? .sdf is re-initialized to empty and copied to bin/debug if newer Existing triggers on the table
- 17. Gotcha’s – primary key Primary key defined on table to cache auto-incrementing integer primary key, unique identity with SQL CE db Some table defaults like newid() for MSSQL Uniqueidentifer field do not transfer to the .sdf schema definition. Set in code <table>.id=Guid.NewGuid Linq can’t autogenerate guid on server. Use id=Guid.NewGuid in code
- 18. Debugging SQL CE 3.5 • SSMS 2005 gives the following error when you try to connect to a SQL CE 3.5 .sdf file. • Created a WinForm project PeekLocalCache to display data from .sdf file. Caution: make sure you know which .sdf file the app is using (bin/debug, bin/release, project) • SSMS 2008 – hopefully works • Be careful re-creating the .sdf file using the local database cache configuration wizard without deleting the records from the Server table. I cleared out the Server table and ran for a while on 11/2 without ex, on 11/3 cleared out the table and ran for 13 records. Changing to update server table, works. Violation is in local cache db
- 19. Switched PK to GUID from Int64
- 20. Set autogen=true in dbml: fail!
- 21. added id = Guid.NewGuid
- 22. Conflict resolution Sorry, not covering in Demos Enums – conflict types (between sync sessions) ClientInsertServerInsert - A new row is created with the same primary key. ClientUpdateServerUpdate - The same row is updated. Most common ClientUpdateServerDelete - A row is updated on the client but was deleted on the server. ClientDeleteServerUpdate - A row is deleted on the client but was updated on the server. ErrorsOccurred – all others Methods for handling Continue RetryApplyingRow RetryWithForceWrite
- 23. Resolution Policies Source wins Destination wins Specified replica wins Last writer wins Merge Log it or defer
- 24. References http://dean-o.blogspot.com/ http://channel9.msdn.com/posts/funkyonex/Offline-Data-Synchronization-Services-in-Visual- Studio-2008/ http://videoworld-rong.blogspot.com/2009/10/adonet-sync-services.html http://social.microsoft.com/Forums/en-US/uklaunch2007ado.net/thread/0fd34e49-ae3d-4b50- 91f5-5e24d4a0b145 http://skysigal.xact-solutions.com/Blog/tabid/427/EntryId/898/Using-LinqToSQL-with-SqlServer- Compact.aspx http://download.microsoft.com/download/A/4/7/A47B7B0E-976D-4F49-B15D- F02ADE638EBE/Compact_Express_Comparison.doc http://www.developer.com/net/article.php/3815506/Handling-Data-Conflicts-in-the-Microsoft- Sync-Framework.htm http://www.geekzone.co.nz/JamesHip/6568 http://code.msdn.microsoft.com/sync http://mattgoebel.spaces.live.com/blog/cns!DB12DAA600AD8227!182.entry?wa=wsignin1.0&sa= 84900002 http://devlicio.us/blogs/billy_mccafferty/archive/2009/11/09/dependency-injection-101.aspx http://stackoverflow.com/questions/385796/sync-framework-can-i-sync-only-a-subset-of-my- tables ASP.NET MVC Framework Unleashed by Stephen Walther, SAMS, ISBN 978-0-672-32998-2
- 25. Thank you! Website http://www.systemental.com Blogs http://dean-o.blogspot.com/ http://practicalhoshin.blogspot.com Twitter http://www.twitter.com/deanwillson Email [email protected] LinkedIn http://www.linkedin.com/in/deanwillson
Editor's Notes
- #4: SQL CE – winform db reader or SSMS 2008
- #9: Show scripts or look at triggers in db. Homework assignment: See how SS knows the .sdf has changes to upload to server. No SS 2008 to look at the schema or attach to Profiler.
- #10: SQL Profiler
- #18: Auto-incrementing integer can cause inserting into client and server with the same primary key
- #19: I was using bigint as the PK, Unique Identifier. This led to intermittent results. Use Guid instead. Apparently SQL CE *doesn’t* support server generated ID’s.