5:01 p.m.
Author: epbernard
Date: 2007-02-07 18:01:44 -0500 (Wed, 07 Feb 2007)
New Revision: 11165
Added:
branches/HAN_SPLIT/HibernateExt/metadata/doc/reference/en/modules/additionalmodules.xml
Log:
oups missing module doc
Added:
branches/HAN_SPLIT/HibernateExt/metadata/doc/reference/en/modules/additionalmodules.xml
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branches/HAN_SPLIT/HibernateExt/metadata/doc/reference/en/modules/additionalmodules.xml
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branches/HAN_SPLIT/HibernateExt/metadata/doc/reference/en/modules/additionalmodules.xml 2007-02-07
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+<?xml version="1.0" encoding="UTF-8"?>
+<chapter id="additionalmodules">
+ <title>Additional modules</title>
+
+ <para>Hibernate Annotations mainly focus on persistence metadata. The
+ project also have a nice integration with two Hibernate modules.</para>
+
+ <section>
+ <title>Hibernate Validator</title>
+
+ <section>
+ <title>Description</title>
+
+ <para>Annotations are a very convenient and elegant way to specify
+ invariant constraints for a domain model. You can, for example, express
+ that a property should never be null, that the account balance should be
+ strictly positive, etc. These domain model constraints are declared in
+ the bean itself by annotating its properties. A validator can then read
+ them and check for constraint violations. The validation mechanism can
+ be executed in different layers in your application without having to
+ duplicate any of these rules (presentation layer, data access layer).
+ Following the DRY principle, Hibernate Validator has been designed for
+ that purpose.</para>
+
+ <para>Hibernate Validator works at two levels. First, it is able to
+ check in-memory instances of a class for constraint violations. Second,
+ it can apply the constraints to the Hibernate metamodel and incorporate
+ them into the generated database schema.</para>
+
+ <para>Each constraint annotation is associated to a validator
+ implementation responsible for checking the constraint on the entity
+ instance. A validator can also (optionally) apply the constraint to the
+ Hibernate metamodel, allowing Hibernate to generate DDL that expresses
+ the constraint. With the appropriate event listener, you can execute the
+ checking operation on inserts and updates done by Hibernate. Hibernate
+ Validator is not limited to use with Hibernate. You can easily use it
+ anywhere in your application.</para>
+
+ <para>When checking instances at runtime, Hibernate Validator returns
+ information about constraint violations in an array of
+ <classname>InvalidValue</classname> s. Among other information, the
+ <classname>InvalidValue</classname> contains an error description
+ message that can embed the parameter values bundle with the annotation
+ (eg. length limit), and message strings that may be externalized to a
+ <classname>ResourceBundle</classname> .</para>
+ </section>
+
+ <section>
+ <title>Integration with Hibernate Annotations</title>
+
+ <para>If Hibernate Validator
+ (<filename>hibernate-validator.jar</filename>) is available in the
+ classpath, Hibernate Annotations will integrates in two ways: </para>
+
+ <itemizedlist>
+ <listitem>
+ <para>Constraints will be applied to the Data Definition Language.
+ In other words, the database schema will reflect the constraints
+ (provided that you use the hbm2ddl tool).</para>
+ </listitem>
+
+ <listitem>
+ <para>Before an entity change is applied to the database (insert or
+ update), the entity is validated. Validation errors, if any, will be
+ carried over through an
+ <classname>InvalidStateException</classname>.</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>For entities free of validation rules, the runtime performance
+ cost is null.</para>
+
+ <para>To disable constraint propagation to DDL, set up
+ <literal>hibernate.validator.apply_to_ddl</literal> to false in the
+ configuration file. Such a need is very uncommon and not
+ recommanded.</para>
+ </section>
+ </section>
+
+ <section>
+ <title>Hibernate Search</title>
+
+ <section>
+ <title>Decription</title>
+
+ <para>Full text search engines like <productname>Apache
+ Lucene</productname> are a very powerful technology to bring free
+ text/efficient queries to applications. If suffers several mismatches
+ when dealing with a object domain model (keeping the index up to date,
+ mismatch between the index structure and the domain model, querying
+ mismatch...) Hibernate Search indexes your domain model thanks to a few
+ annotations, takes care of the database / index synchronization and
+ brings you back regular managed objects from free text queries.
+ Hibernate Search is using <ulink
url="http://lucene.apache.org">Apache
+ Lucene</ulink> under the cover.</para>
+ </section>
+
+ <section>
+ <title>Integration with Hibernate Annotations</title>
+
+ <para>Hibernate Search integrates with Hibernate Annotations through
+ Hibernate event listeners definitions, please check the Hibernate Search
+ reference documentation for more information.</para>
+ </section>
+ </section>
+</chapter>
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