Object Relational Mapping From A to Z

Transcript

1. Object Relational Mapping A to Z
2. About Me Over A Decade of I.T. Experience Web Developer, DBA, DevOps, Mobile Microsoft Cert. in SQL Server Twitter: @greeleygeek E-Mail: anthem001@gmail.com
3. Summary • What an Object Relational Mapper Is • Why you might use an Object Relational Mapper • Problems using Object Relational Mapper • Solutions to common issues • Popular Object Relational Mapper examples • Debugging • Final Tips
4. What Is It? • Wikipedia: …”technique for converting data between incompatible type systems in object- oriented programming languages. This creates, in effect, a ‘virtual object database’ that can be used from within the programming language” • “Maps” set based data to objects useable by Object Oriented languages.
5. What Is An ORM
6. What is An ORM? © Universal Studios. All rights Reserved.
7. What Is An ORM? • Database Management Systems: ~1960 • Object Oriented Programming: ~50s/60s • One of the first ORMs was TopLink for SmallTalk in 1994
8. Popular Flavors
9. What Is An ORM?
10. Object Impedance Mismatch Wikipedia defines this as: “…conceptual and technical difficulties that are often encountered when a relational database management system (RDBMS) is being used by a program written in an object- oriented programming language or style; particularly when objects or class definitions are mapped in a straightforward way to database tables or relational schemata.”
11. The “ORM problem” http://upload.wikimedia.org/wikipedia/commons/7/76/Bruce_Crandall%27s_UH-1D.jpg
12. Solutions • Abandon the Object Model altogether returning to traditional methods • Use a storage method that is object oriented itself (OODBMS, NoSQL possibly) • Hand-crafting each Mapping • Mix of ORM and SQL • Integrate datasets into language itself (think LINQ) • Build solution on relational concepts (blocks of data)
13. The Good News
14. Taking A Peek
15. NHibernate Demo
16. NHibernate Demo
17. NHibernate Demo
18. NHibernate Demo NHibernate
19. NHibernate Demo
20. NHibernate Demo
21. Nhibernate Demo
22. NHibernate Demo
23. Taking A Peek
24. Entity Framework
25. Entity Framework
26. Entity Framework
27. Entity Framework
28. Entity Framework
29. Entity Framework
31. Entity Framework
32. Entity Framework
33. Entity Framework
34. Entity Framework
35. Micro ORM • Slimmed down ORMs • What they lack in features they make up for in speed • Popular flavors are PetaPoco and Dapper
36. Massive
37. Massive
38. Massive
39. Massive
40. Massive Demo
41. Debugging An ORM Demo
42. ORM Pros • Simpler for developers • Supports many database platforms • Supports many different languages • The impedance mismatch is handled for us • Developer can focus on the code, not the database
43. ORM Cons • Can be cumbersome to set up (NHibernate) • Joins and complex queries can be difficult • Hard to read performance metrics • Another layer between the database and the application.
44. Final Thoughts • ORMs continue to advance • Work for most solutions • Consider stored procedures or views for finer control.
45. Code Links • NHibernate Demo Source Code: https://github.com/anthem001/NHibernateDemo • Entity Framework Demo Source Code: https://github.com/anthem001/EntityFrameworkDemo • Massive Micro ORM Demo Source Code: https://github.com/anthem001/MassiveORMDemo • Slides posted at: http://zero1design.com Twitter: @greeleygeek E-Mail: anthem001@gmail.com