Persistence

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 (Last Modifier)	Creation Date	Last Mod Date	Comment
	Persistence-Iteration_4-Vancouver_Bootcamp.ppt	573 kB	Aaron Zeckoski	May 30, 2006	May 30, 2006	Updated powerpoint presentation for Vancouver
	SakaiPersistenceAndHibernate.ppt	371 kB	Aaron Zeckoski	Jun 05, 2008	Jun 05, 2008	Presentation on Hibernate and persistence

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