Hibernate

Hibernate is Framework, which is written in Java. It allows object-relational mapping (ORM). It can simplify the data retention of objects after finishing the data’s run. It is one of the Java Persistence API (JPA) implementation. The original creator of Hibernate is Gavin King, who then with his Hibernate went to the JBoss company. In 2006, the JBoss company was taken over by Red Hat company, which continued with the framework’s development.

Hibernate’s role in development

Hibernate provides way, which allows retention of the objects’ state between two application executions. It maintains persistent data. It allows ORM, i. e. mapping Java objects to entities stored in relational databases. During this process, it uses mapping files, which describe how should the data from given object transform into database and vice versa and how should the object creation from database tables happen.

Alternative way how is possible to map objects, is usage of annotation instead of mapping files. In Hibernate is worked with usual business objects, then the table’s columns can be connected directly to attributes of these objects or there can be connection through get/set methods and hashCode() or equals() methods.

There is a need to remind that there is not possible to use EJB, but exclusively classical objects, i. e. POJO (Plain Old Java Object). Then, once are the objects stored in database, they can be inquired about usage of HQL (Hibernate Query Language) language. It is derived from SQL and it is also very similar to it.

Alternate ways of mapping

Hibernate can use mapping with the help of mapping files or annotations:

• Mapping files are files in XML format, for each individual class is one file, which is typically placed in the same package as the class.
• Annotations are possible to use in two different ways. Either they are directly at the attributes or at their getters.

Advantages of using Hibernate

• Hibernate is better than the clean JDBC. It is enough to use Hibernate, which generates SQL and then automatically executes the necessary SQL commands. It saves much of the development, which would be needed for the manual creation of a similar solution.
• Mapping domain objects to relational databases. Hibernate maps domain objects on the relational database, which allows developers to focus more on business logic rather than managing data in database.
• Layered architecture. Hibernate has a layered architecture and it is possible to use individual components according to the needs of particular application.
• JPA provider. Hibernate can function as JPA provider in applications based on JPA.
• Independence on databases. Hibernate database is independent and is possible to use random database.
• Caching Framework. There are many caching Frameworks, which function with Hibernate. You can use any of them in your app to improve her efficiency.
• Support of inheritance and polymorphism.
• Support of various relationships. Hibernate supports relationships one to one, one to n, n to one and n to m.

Disadvantages of using Hibernate

• Necessity to learn more complicated API. There is a lot of time needed to learn the Hibernate.
• Debugging. Debugging and optimization of efficiency can be relatively difficult activities.
• Slower than JDBC. Hibernate is slower than clear JDBC, regarding to that it generates many SQL commands.
• It is not suitable for processing by the Batch form. For Batch processing is more suitable to use clear JDBC.
• It is not suitable for smaller projects. For small projects, which have only a few tables, is the work with Hibernate useless.
• It generates complicated queries to the database with many joins.