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spring-ldap/src/docbkx/odm.xml
2010-11-15 16:35:57 +00:00

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<chapter id="odm">
<title>Object-Directory Mapping (ODM)</title>
<sect1 id="odm-intro">
<title>Introduction</title>
<para>Relational mapping frameworks like Hibernate and JPA have offered
developers the ability to use annotations to map database tables to Java
objects for some time. The Spring Framework LDAP project now offers the
same ability with respect to directories through the use of the
<code>org.springframework.ldap.odm</code> package.</para>
</sect1>
<sect1 id="odm-odmmanager">
<title>OdmManager</title>
<para>The
<code>org.springframework.ldap.odm.OdmManager</code>
interface, and its implementation, is the central class in the ODM
package. The <code>OdmManager</code> orchestrates the
process of reading objects from the directory and mapping the data to
annotated Java object classes. This interface provides access to the
underlying directory instance through the following methods:</para>
<itemizedlist>
<listitem>
<para><code>&lt;T&gt; T read(Class&lt;T&gt; clazz, Name
dn)</code></para>
</listitem>
<listitem>
<para><code>void create(Object entry)</code></para>
</listitem>
<listitem>
<para><code>void update(Object entry)</code></para>
</listitem>
<listitem>
<para><code>void delete(Object entry)</code></para>
</listitem>
<listitem>
<para><code>&lt;T&gt; List&lt;T&gt; findAll(Class&lt;T&gt; clazz, Name
base, SearchControls searchControls)</code></para>
</listitem>
<listitem>
<para><code>&lt;T&gt; List&lt;T&gt; search(Class&lt;T&gt; clazz, Name
base, String filter, SearchControls searchControls)</code></para>
</listitem>
</itemizedlist>
<para>A reference to an implementation of this interface can be obtained
through the
<code>org.springframework.ldap.odm.core.impl.OdmManagerImplFactoryBean</code>.
A basic configuration of this factory would be as follows:</para>
<example>
<title>Configuring the OdmManager Factory</title>
<programlisting><![CDATA[
<beans>
...
<bean id="odmManager" class="org.springframework.ldap.odm.core.impl.OdmManagerImplFactoryBean">
<property name="converterManager" ref="converterManager" />
<property name="contextSource" ref="contextSource" />
<property name="managedClasses">
<set>
<value>com.example.dao.SimplePerson</value>
</set>
</property>
</bean>
...
</beans>
]]></programlisting>
</example>
<para>The factory requires the list of entity classes to be managed by the
<code>OdmManager</code> to be explicitly declared. These
classes should be properly annotated as defined in the next section. The
<code>converterManager</code> referenced in the above definition
is described in <xref
linkend="odm-typeconversion" />.</para>
</sect1>
<sect1 id="odm-annotations">
<title>Annotations</title>
<para>Entity classes managed by the
<code>OdmManager</code> are required to be annotated
with the annotations in the
<code>org.springframework.ldap.odm.annotations</code> package. The
available annotations are:</para>
<itemizedlist>
<listitem>
<para><code>@Entry</code> - Class level annotation indicating the
<code>objectClass</code> definitions to which the entity
maps.<emphasis> (required)</emphasis></para>
</listitem>
<listitem>
<para><code>@Id</code> - Indicates the entity DN; the field declaring
this attribute must be a derivative of the
<code>javax.naming.Name</code> class.
<emphasis>(required)</emphasis></para>
</listitem>
<listitem>
<para><code>@Attribute</code> - Indicates the mapping of a directory
attribute to the object class field.</para>
</listitem>
<listitem>
<para><code>@Transient</code> - Indicates the field is not persistent
and should be ignored by the
<code>OdmManager</code>.</para>
</listitem>
</itemizedlist>
<simpara>The <code>@Entry</code> and <code>@Id</code> attributes are
required to be declared on managed classes. <code>@Entry</code> is used to
specify which object classes the entity maps too. All object classes for
which fields are mapped are required to be declared. Also, in order for a
directory entry to be considered a match to the managed entity, all object
classes declared by the directory entry must match be declared by in the
<code>@Entry</code> annotation. </simpara>
<simpara>The <code>@Id</code> annotation is used to map the distinguished
name of the entry to a field. The field must be an instance of
<code>javax.naming.Name</code> or a subclass of it.</simpara>
<simpara>The <code>@Attribute</code> annotation is used to map object
class fields to entity fields. <code>@Attribute</code> is required to
declare the name of the object class property to which the field maps and
may optionally declare the syntax OID of the LDAP attribute, to guarantee
exact matching. <code>@Attribute</code> also provides the type declaration
which allows you to indicate whether the attribute is regarded as binary
based or string based by the LDAP JNDI provider.</simpara>
<simpara>The <code>@Transient</code> annotation is used to indicate the
field should be ignored by the <code>OdmManager</code>
and not mapped to an underlying LDAP property.</simpara>
</sect1>
<sect1 id="odm-typeconversion">
<title>Type Conversion</title>
<para>The <code>OdmManager</code> relies on the
<code>org.springframework.ldap.odm.typeconversion</code> package to
convert LDAP attributes to Java fields. The main interface in this class
is the
<code>org.springframework.ldap.odm.typeconversion.ConverterManager</code>.
The default <code>ConverterManager</code> implementation
uses the following algorithm when parsing objects to convert
fields:<orderedlist>
<listitem>
<para>Try to find and use a <code>Converter</code>
registered for the <code>fromClass</code>,
<code>syntax</code> and <code>toClass</code> and use
it.</para>
</listitem>
<listitem>
<para>If this fails, then if the <code>toClass</code>
<code><methodname>isAssignableFrom</methodname></code> the
<code>fromClass</code> then just assign it.</para>
</listitem>
<listitem>
<para>If this fails try to find and use a
<code><code>Converter</code></code> registered for
the <code>fromClass</code> and the
<code>toClass</code> ignoring the syntax.</para>
</listitem>
<listitem>
<para>If this fails then throw a
<exceptionname>ConverterException</exceptionname>.</para>
</listitem>
</orderedlist></para>
<para>Implementations of the <code>ConverterManager</code>
interface can be obtained from the
<code>org.springframework.ldap.odm.typeconversion.impl.ConvertManagerFactoryBean</code>.
The factory bean requires converter configurations to be declared in the
bean configuration. </para>
<para>The converterConfig property accepts a set of
<code>ConverterConfig</code> classes, each one defining some
conversion logic. A converter config is an instance of
<code>org.springframework.ldap.odm.typeconversion.impl.ConverterManagerFactoryBean.ConverterConfig</code>.
The config defines a set of source classes, the set of target classes, and
an implementation of the
<code>com.springframework.ldap.odm.typeconversion.impl.Converter</code>
interface which provides the logic to convert from the
<code>fromClass</code> to the <code>toClass</code>. A
sample configuration is provided in the following example:</para>
<example>
<title>Configuring the Converter Manager Factory</title>
<programlisting><![CDATA[
<bean id="fromStringConverter"
class="org.springframework.ldap.odm.typeconversion.impl.converters.FromStringConverter" />
<bean id="toStringConverter"
class="org.springframework.ldap.odm.typeconversion.impl.converters.ToStringConverter" />
<bean id="converterManager"
class="org.springframework.ldap.odm.typeconversion.impl.ConverterManagerFactoryBean">
<property name="converterConfig">
<set>
<bean class="org.springframework.ldap.odm.typeconversion.impl.ConverterManagerFactoryBean$ConverterConfig">
<property name="fromClasses">
<set>
<value>java.lang.String</value>
</set>
</property>
<property name="toClasses">
<set>
<value>java.lang.Byte</value>
<value>java.lang.Short</value>
<value>java.lang.Integer</value>
<value>java.lang.Long</value>
<value>java.lang.Float</value>
<value>java.lang.Double</value>
<value>java.lang.Boolean</value>
</set>
</property>
<property name="converter" ref="fromStringConverter" />
</bean>
<bean class="org.springframework.ldap.odm.typeconversion.impl.ConverterManagerFactoryBean$ConverterConfig">
<property name="fromClasses">
<set>
<value>java.lang.Byte</value>
<value>java.lang.Short</value>
<value>java.lang.Integer</value>
<value>java.lang.Long</value>
<value>java.lang.Float</value>
<value>java.lang.Double</value>
<value>java.lang.Boolean</value>
</set>
</property>
<property name="toClasses">
<set>
<value>java.lang.String</value>
</set>
</property>
<property name="converter" ref="toStringConverter" />
</bean>
</set>
</property>
</bean>
]]></programlisting>
</example>
</sect1>
<sect1 id="odm-execution">
<title>Execution</title>
<para>After all components are configured, directory interaction can be
acheived through a reference to the
<code>OdmManager</code> as shown in this example:</para>
<example>
<title>Execution</title>
<programlisting><![CDATA[
public class App {
private static Log log = LogFactory.getLog(App.class);
private static final SearchControls searchControls =
new SearchControls(SearchControls.SUBTREE_SCOPE, 100, 10000, null, true, false);
public static void main( String[] args ) {
try {
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
OdmManager manager = (OdmManager) context.getBean("odmManager");
List<SimplePerson> people = manager.search(
SimplePerson.class, new DistinguishedName("dc=example,dc=com"), "uid=*", searchControls);
log.info("People found: " + people.size());
for (SimplePerson person : people) {
log.info( person );
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
]]></programlisting>
</example>
</sect1>
</chapter>