Hibernate and the InterSystems Hibernate Dialect
Java Persistence Architecture (JPA) is the recommended persistence technology for complex object hierarchies in Java projects. InterSystems currently supports JPA via the Hibernate implementations of the JPA specifications. Hibernate is an open source framework from JBoss that acts as a wrapper around JDBC to provide object/relational mapping (ORM) services for relational databases. Hibernate provides a vendor-neutral persistence service, which may be a requirement for some projects.
The InterSystems Hibernate Dialect is an implementation of the Hibernate dialect interface. Since every vendor’s implementation of SQL is slightly different, Hibernate includes vendor-provided "dialects" that customize its mappings to specific databases. Current Hibernate distributions include a high performance, customized InterSystems dialect class.
When to Use Hibernate
Hibernate provides the infrastructure to persist objects to relational tables. Essentially, it is a wrapper around JDBC that allows you to focus on working with objects while transparently handling conversion between objects and tables in SQL queries. Hibernate can be used in most environments, but it is not always the best option. Here are some considerations to bear in mind:
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Hibernate is helpful when you have a complex but static object model. You must know what your data looks like and how the classes interact before you map them to your InterSystems IRIS table model.
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Since Hibernate objects are cached, other applications should never interact with the data while Hibernate is accessing it. If you are working in an environment with real-time data that must remain accessible to other applications, you should consider XEP (see Persisting Java Objects with InterSystems XEP) as a possible alternative.
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Hibernate is good for common CRUD operations with simple querying, but more complex queries may be easier to write, or more efficient, using JDBC directly.
