Using Hibernate POJO with GWT generally leads to two issues :

• Lazy properties issue : when trying to send a partially loaded Hibernate POJO to the client-side of GWT (Javascript), the GWT compiler throws a Serialization exception because it the CGLIB generated proxy does not belong to the JRE emulation.

• Type issue : Hibernate replaces some basic Java types with various subclassed implementation (such as java.sql.Timestamp instead of java.util.Date or PersistentList for List collections). Javascript serialization of these classes will fail, since they do not belong to the JRE emulation supported by GWT 1.4 (note : the Java SQL dates are now supported by GWT 1.5)