Persistence

Persistence in Sakai - Former user (Deleted)

• 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
    • File / binary stream storage available (using content hosting service), example: resources/dropbox tool
• 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
• JDBC in Sakai
• 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
  • Tasklist Project XML Hibernate dependency
  • Tasklist Hibernate 3 HBM file
  • Tasklist Task object
  • Implementing the Manager API by extending HibernateDaoSupport
  • Spring injection of the SessionFactory
  • Build and Test