My presentation on JUDCon Brazil 2013 - Santo Amaro, SP

2. Envers + Seam + JBoss: Why
to use?
Diogo Souza

3. Envers + Seam + JBoss:
Why to use?
Better...

4. The handshake

5. Diogo Souza
Systems Analyst at Indra Company
http://3adiX.com.br
http://diogosouza.com.br
@diogo_souza_c

6. Ah, the Envers!
Once upon a time, in 2009…

7. What they say about…
“The Envers project aims to enable
easy auditing/versioning of persistent
classes […]”
Ref: http://www.jboss.org/envers

8. What they say about…
“[…] All that you have to do is
annotate your persistent class or
some of its properties, that you want
to audit, with @Audited. […]”
Ref: http://www.jboss.org/envers

9. What they say about…
“[…] For each audited entity, a table
will be created, which will hold the
history of changes made to the
entity. […]”
Ref: http://www.jboss.org/envers

10. And the best part…
“[…] You can then retrieve and query
historical data without much effort.”
Ref: http://www.jboss.org/envers
http://www.deviantart.com

11. Some features:
 Auditing of all mappings defined by
the JPA specification
 Auditing of some Hibernate
mappings, which extend JPA
 Logging data for each revision using
a "revision entity"
 Querying historical data
Ref: http://www.jboss.org/envers
http://www.deviantart.com

12. Basically
Each transaction...
...One revision
INSERT
UPDATE
DELETE

13. Where to use?
Wherever you have Hibernate!
 Standalone
 JBoss AS
 Spring

14. And how do we use in the past?
<property name="hibernate.ejb.event.post-insert"
value="org.hibernate.ejb.event.EJB3PostInsertEventListener,org.hibernat
e.envers.event.AuditEventListener" />
<property name="hibernate.ejb.event.post-update"
value="org.hibernate.ejb.event.EJB3PostUpdateEventListener,org.hiberna
te.envers.event.AuditEventListener" />
<property name="hibernate.ejb.event.post-delete"
value="org.hibernate.ejb.event.EJB3PostDeleteEventListener,org.hibernat
e.envers.event.AuditEventListener" />
<property name="hibernate.ejb.event.pre-collection-update"
value="org.hibernate.envers.event.AuditEventListener" />
<property name="hibernate.ejb.event.pre-collection-remove"
value="org.hibernate.envers.event.AuditEventListener" />
<property name="hibernate.ejb.event.post-collection-recreate"
value="org.hibernate.envers.event.AuditEventListener" />
In persistence.xml or hibernate.cfg.xml

15. And how to use?
<!-- Add on classpath | Maven -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-envers</artifactId>
<version>4.x.Final</version>
</dependency>
Requirements:
Hibernate 3+
Hibernate annotations

16. Simple sample
@Entity
public class Adress {
@Id
@GeneratedValue
private int id;
@Audited
private String streetName;
@Audited
private Long zipCode;
@Audited
@ManyToOne
private State state;
}

17. The whole entity
@Audited
public class Adress {
@Id
@GeneratedValue
private int id;
private String streetName;
private Long zipCode;
@ManyToOne
private State state;
}
@Audited // Here too!
public class State {
@Id
@GeneratedValue
private int id;
private String stateName;
private Long population;
}

18. … without a field
@Audited
public class Adress {
@Id
@GeneratedValue
private int id;
@NotAudited
private String streetName;
private Long zipCode;
@ManyToOne
private State state;
}

19. Changing the entity table
name
@Audited
@AuditTable(“TB_ADRESS_AUDIT”)
public class Adress {
@Id
@GeneratedValue
private int id;
@NotAudited
private String streetName;
private Long zipCode;
@ManyToOne
private State state;
}

20. The database
0 ADD
1 MOD
3 DEL
The revision
date!

21. Querying for entities of a
class at a given revision
AuditQuery query =
getAuditReader().createQuery()
.forEntitiesAtRevision(MyEntity.class,
revisionNumber);

22. Querying for revisions, at
which entities of a given class
changed
AuditQuery query =
getAuditReader().createQuery()
.forRevisionsOfEntity(MyEntity.class,
false, true);

23. Querying for revisions
between revision dates
AuditReader auditReader =
AuditReaderFactory.get(entityManager);
AuditQuery query = auditReader.createQuery()
.forRevisionsOfEntity(Punishment.class, false, true)
.add(AuditEntity.revisionProperty("timestamp")
.gt(timeStamp).lt(otherTimeStamp)
.add(AuditEntity.revisionType().eq(RevisionType.ADD));
List<Object[]> revisions = query.getResultList();

24. Configuration Properties
// Prefixes and suffixes
org.hibernate.envers.audit_table_prefix
org.hibernate.envers.audit_table_suffix
// Revision number and revision type fields
org.hibernate.envers.revision_field_name
org.hibernate.envers.revision_type_field_name
// Default schema used
org.hibernate.envers.default_schema

25. Demo Time!

26. I am not responsible for
any increases in the
number of Brazilian
punishments...

27. The guy!
Adam Warski
Ref: http://www.warski.org/blog/about/
http://warski.org

28. Good things!
 Easy!
 Data as always!
 Database schema
doesn’t change
 Minimal code changes
 Integration with
Hibernate/Red Hat
related

29. Not so good things!
 Dependency of
Hibernate.
 Not compatible with
Hibernate-XML-Age.
 Extra table for each
table.

30. Story Time!

31. References/Links
 www.jboss.org/envers
 http://docs.jboss.org/envers/docs/
 http://www.warski.org/blog/

32. Thanks! 