Persistence - WG: Programmer's Cafe

Persistence in Sakai - Aaron Zeckoski

What is persistence?
- Taking temporary data (like in-memory program data) and storing it in a more permanent form
- Putting program data somewhere so you can retrieve it later (e.g. after a restart)
- Writing the information in your Java objects somewhere so you can get to it again after they are destroyed
How do we persist data in Sakai?
- Pretty much always use the database
  - Optional file system storage for tools like resources (content hosting)
Databases and Sakai
- Settings are in the sakai.properties file
- 3 accepted ways to persist data to the database
  - JDBC - advantages and disadvantages? same as Spring JDBC but harder to use!
  - Spring JDBC - advantages and disadvantages? not ORM, more work, more control
  - Hibernate - advantages and disadvantages? ORM, easier, less control
Hibernate in Sakai
- 3 ways of using Hibernate in Sakai (powerpoint)
1. Create a SessionFactory using settings inside your tool
  - Note: Only use this for accessing external databases (out of scope for these docs)
    - SessionFactory Config Docs
2. Create a session factory from the global Sakai sessionFactoryBase
  - We will use this method for the workshop and the Task List Tool Exercise
3. Add our HBMs to the global Sakai sessionFactory
  - This method is demonstrated in this version of the tasklist tool: tasklist-complex
Example - Enhance Task List Tool to persist tasks

	Name	Size	Creator	Date	Comment
	Persistence-Iteration_4-Vancouver_Bootcamp.ppt	573 kb	Aaron Zeckoski	May 30, 2006	Updated powerpoint presentation for Vancouver
	SakaiPersistenceAndHibernate.ppt	371 kb	Aaron Zeckoski	Jun 05, 2008	Presentation on Hibernate and persistence