Agile Enterprise Application Development with Flex

Integrating with the Hibernate Framework

These days, writing SQL manually is out of style, and lots of software developers prefer using object-relational mapping (ORM) tools for data persistence. With ORM, an instance of an object is mapped to a database table. Selecting a row from a database is equivalent to creating an instance of the object in memory. On the same note, deleting the object instance will cause deletion of the corresponding row in a database table.

In the Java community, Hibernate is the most popular open source ORM tool. Hibernate supports lazy loading, caching, and object versioning. It can either create the entire database from scratch based on the provided Java objects, or just create Java objects based on the existing database.

Mapping of Java objects to the database tables and setting their relationships (one-to-many, one-to-one, many-to-one) can be done either externally in XML configuration files or by using annotations right inside the Java classes, a.k.a. entity beans. From a Flex remoting perspective, nothing changes: Flex still sends and receives DTOs from a destination specified in remoting-config.xml.

After downloading and installing the Hibernate framework under the server with BlazeDS, the integration steps are:

1. Create a server-side entity bean Employee that uses annotations to map appropriate values to database tables and specify queries:

   @Entity @Table(name = "employees") @NamedQueries( { @NamedQuery(name = "employeess.findAll", query = "from Employee"), ...