User: vharcq
Date: 01/06/24 14:39:03
Modified: src/docs customizingjaws.xml
Log:
Added chapter/example on Dependant Value Object
Revision Changes Path
1.12 +80 -0 manual/src/docs/customizingjaws.xml
Index: customizingjaws.xml
===================================================================
RCS file: /cvsroot/jboss/manual/src/docs/customizingjaws.xml,v
retrieving revision 1.11
retrieving revision 1.12
diff -u -r1.11 -r1.12
--- customizingjaws.xml 2001/06/24 09:59:00 1.11
+++ customizingjaws.xml 2001/06/24 21:39:03 1.12
@@ -615,4 +615,84 @@
find you have to modify it, please consider sharing your changes:
post the modified mapping on the jbosscmp mailing list.</para>
</section>
+ <section>
+ <title>Dependant Value Objects [since JBoss 2.4]</title>
+ <para>Author:
+ <author>
+ <firstname>Vincent</firstname>
+ <surname>Harcq</surname>
+ </author>
+ <email>[EMAIL PROTECTED]</email>
+ </para>
+ <para>Standards compliance note: this feature is not standard or required in
EJB 1.1. Therefore, EJBs that
+use this feature, might not be compile-free portable to other EJB containers.</para>
+ <para>JAWS store non primitive type fields as Object in the database. When
the field is a JavaBean, an object with
+ some primitive type attributes with getter/setter accessing methods, it is
possible to store the value of these attributes
+instead of the whole object.</para>
+<para>For example suppose in the Class bean, we have a field "lesson" representing
the subject (english, mathematics,..)
+and the number of hours that the teacher take to give its lesson. This field is an
simple JavaBean:</para>
+<programlisting><![CDATA[
+package org.jboss.docs.cmp.jaws.interfaces;
+
+import java.io.Serializable;
+
+public class LessonDetail
+implements Serializable{
+
+ private String subject;
+ private Integer hours;
+
+ public String getSubject(){ return subject; }
+ public void setSubject(String subject){ this.subject = subject; }
+
+ public Integer getHours(){ return hours; }
+ public void setHours(Integer hours){ this.hours = hours; }
+
+}
+]]></programlisting>
+<para>The ejb-jar.xml will still define "lesson" as the CMP field:</para>
+<programlisting><![CDATA[
+<ejb-jar>
+ <display-name>Class</display-name>
+ <enterprise-beans>
+ <entity>
+ ...
+ <cmp-field><field-name>lesson</field-name></cmp-field>
+ ...
+ </entity>
+ </enterprise-beans>
+</ejb-jar>
+
+]]></programlisting>
+<para>But jaws.xml will say how to store/retrieve
+the object:</para>
+<programlisting><![CDATA[
+<jaws>
+ <enterprise-beans>
+ <entity>
+ ...
+ <cmp-field>
+ <field-name>lesson.subject</field-name>
+ <column-name>LESSON_SUBJECT</column-name>
+ </cmp-field>
+ <cmp-field>
+ <field-name>lesson.hours</field-name>
+ <column-name>HOURS</column-name>
+ </cmp-field>
+ ...
+ </entity>
+ </enterprise-beans>
+</jaws>
+]]></programlisting>
+<para>Two database fields are now used to store the "value" of the object. The
trick is to have getter/setter method
+corresponding to what you have to store/retrieve.</para>
+<para>This feature is recursive, so you can have something like
lesson.subject.name, lesson.subject.group,...</para>
+<para>Notice that if the dependant object defines its attributes as "public", the
getter/setter methods are not necessary.
+This can be used in an entity bean to store a reference to another entity bean by
its Primary Key object. Indeed, in
+this case, the primary key fields are declared as public in the PK class.</para>
+<para>Finally notice that even if this a non standard requirement in EJB 1.1, there
is a way to program this in a standard way.
+This is to define the 2 CMP fields in the bean and access them through
getter/setter method of "LessonDetail" type.
+These will map the database fields to the object and vice versa. A more performant
solution is to keep a private "LessonDetail"
+attribute in the bean that is construct in the ejbLoad() method.</para>
+ </section>
</chapter>
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