This document provides an introduction and overview of NHibernate, an object-relational mapper for .NET. It discusses what ORM is, the benefits it provides, and gives a high-level overview of how NHibernate works. It then walks through setting up a sample project using NHibernate to map classes and database tables, configure the session factory, implement a DAO using transactions to perform CRUD operations.

1. NHibernate for .NET Albert Kuo 1

2. Introduction to ORM Introduction to NHibernate Scenario NHibernate Demo Demo Process Hibernate-config.xml Mapping files & classes SessionManager DAO (Data Access Object) Create ASPX to do testing Reference 2 Agenda

3. Introduction to ORM 3

4. Object-relational mapping (aka ORM, O/RM, and O/R mapping) is a programming technique for converting data between incompatible type systems in relational databases and object-oriented programming languages (Wikipedia) Objects are hierarchical Databases are relational What is ORM? ORM objects relational 4

5. Productivity Eliminates lots of repetitive code – focus on business logic Database schema is generated automatically Maintainability Fewer lines of code – easier to understand Easier to manage change in the object model Performance Lazy loading – associations are fetched when needed Caching Database vendor independence The underlying database is abstracted away Can be configured outside the application ORM Benefits 5

6. 6 ORM and Architacture Oracle, MS SQL Server, DB2, MySQL, Sybase, etc.

7. Introduction to NHibernate 7

8. Initially developed for Java created in late 2001 by Gavin King absorbed by the JBossGroup / Red Hat Ported to .NET 1.1, 2.0, 3.5 Resulting product called “NHibernate” All popular databases supported Oracle, SQL Server, DB2, SQLite, PostgreSQL, MySQL, Sybase, Firebird, … XML-based configuration files Good community support Free/open source -NHibernateis licensed under the LGPL (Lesser GNU Public License) Introduction to NHibernate 8

9. 9 High-level overview of the Nhibernate API

10. NHibernate managing database access 10

11. 11 Access Persistent Object

12. ISessionFactory One per database (or application) Expensive to create Reads configuration ISession Portal to the database Saves, retrieves ITransaction Encapsulates database transactions Nhibernate in a Nutshell 12

13. Scenario 13

14. One people may have more than one contact One contact belongs to one people 14 Database schema

15. 15 Use Case Diagram

16. 16 Sequence diagram – create

17. 17 Sequence diagram – Read

18. 18 Sequence diagram – Update

19. 19 Sequence diagram – Delete

20. 20 Project Directories Stored persistence tier-related code Stored presentation tier-related code Data access objects Value objects and mapping files

21. NHibernate 21

22. 22 Demo Process

23. 23

24. 24 Hibernate-config.xml

25. 25

26. <class> declare a persistent class <id> defines the mapping from that property to the primary key column Specifies strategy <property> declares a persistent property of the class <component> maps properties of a child object to columns of the table of a parent class. Associations One-to-Many Many-to-One Many-to-Many One-to-One (uncommon) 26 Mapping Concepts

27. 27 Mapping Collections

28. 28 Mapping files & classes ORM objects relational

29. 29 Mapping files & classes – cont.

30. 30 Mapping files & classes – cont.

32. Responsible for storing and retrieving objects

34. 33 DAO (Data Access Object) – cont.

35. 34 DAO (Data Access Object) – cont.

36. 35 DAO (Data Access Object) – cont.

37. 36

38. Transaction: A set of database operations which must be executed in entirety or not at all Should end either with a commit or a rollback All communication with a database has to occur inside a transaction! 37 Transactions

39. 38 Transactions – cont.

40. Create a new record

41. 40 Read data by criteria

42. Update record

43. 42 Delete record

44. O/R Mapping http://en.wikipedia.org/wiki/Object-relational_mapping Official site www.hibernate.org NHibernate in Action NHibernate Made Simple http://www.codeproject.com/KB/database/Nhibernate_Made_Simple.aspx NHibernate Best Practices http://www.codeproject.com/KB/architecture/NHibernateBestPractices.aspx 43 Reference