To summarize the points made, the following are on the horizon as possible directions for Hibernate 3:
Virtualization:
Session-level filtering of data. For example, you may wish to allow only data that belongs to a particular user to be viewed across an entire Web application. The virtualization feature will allow you to specify this at the session, instead of in your application code. This feature will probably be of special interest to Web application developers.
More Complex Relationships:
As described in Chapter 7, Hibernate already offers support for a variety of complex relationships. Hibernate 3 will allow the use of a single class for multiple tables, table-per-concrete-class mappings, and the ability to use SQL to specify more complex discriminators.
Representation Independence:
Allows a persistence model to be represented using entirely dynamic objects, instead of persistent objects. At some point, you may have realized that most JavaBeans could just as easily be represented by a single object with a single get/set property method (as described by the Apache BeanUtils, http://jakarta.apache.org/commons/beanutils/). This feature allows for a much broader suite of dynamic (i.e., runtime) discovery and manipulation of data.
JDK 1.5 Support:
For more information on JDK 1.5, see http://java.sun.com/j2se/. Annotations allow XDoclet-style metadata to be embedded in a Java class file and easily accessed at runtime. Generics allow for more typesafe collections (i.e., less casting, more reliable compile-type checking).
Stored Procedures:
This would be quite relevant if you are working on an application with legacy stored procedures.
Event-Driven Design:
While the life-cycle methods described in Chapter 6 are reasonable, Hibernate lacks a full event model. Currently, the only way to instrument Hibernate to perform certain tasks is to download the source for Hibernate and add your own hooksand that is not the ideal situation.
New Parser Implementation:
The grammar for HQL (as described in Chapter 8) is not fully documented and can be frustratingly vague in certain areas. Hibernate 3 should include a full grammar for HQL, as well as the ability to map new grammars on top of the existing implementation.
Declarative Session Management:
Instead of session management constituting an explicit part of the application, Hibernate 3 will offer the ability to push this sort of detail into Hibernate and the session configuration.
Despite these changes, Hibernate 3 will not require JDK 1.5. As of this writing, Hibernate 3 is not even available as an alpha technology release.
