[Jakarta Tapestry Wiki] Updated: SpringHibernate

[ta...@jakarta.apache.org]

   Date: 2005-02-28T20:22:14
   Editor: HenriDupre
   Wiki: Jakarta Tapestry Wiki
   Page: SpringHibernate
   URL: http://wiki.apache.org/jakarta-tapestry/SpringHibernate

   no comment

Change Log:

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@@ -3,6 +3,174 @@
 Two approaches are possible for using hibernate with Tapestry: with Spring or write your own engine services to deal with sessions.
 The Spring approach offers an (almost) transparent session management and declarative transactions.
 
-I recommend to use Hibernate 3 which offers several major improvements over the 2.1. A preliminary support for Hibernate 3 and Spring is available at http://opensource.atlassian.com/projects/spring/browse/SPR-300
+Hibernate 3 offers several major improvements over the 2.1. A preliminary support for Hibernate 3 and Spring is available at http://opensource.atlassian.com/projects/spring/browse/SPR-300
 
+With Spring, the way to go is to use the "OpenSessionInViewFilter" which opens and closes hibernate sessions for you in a transparent way. These lines are required in the web.xml to enable the session management:
+	<filter>
+		<filter-name>hibernateFilter</filter-name>
+		<filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class>
+	</filter>
 
+	<filter-mapping>
+		<filter-name>hibernateFilter</filter-name>
+                <!-- put here your own path for your Tapestry url-pattern -->
+		<url-pattern>/exec</url-pattern> 
+	</filter-mapping>
+
+	<listener>
+		<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
+	</listener>
+
+For the applicationContext.xml, my file is based on https://betterpetshop.dev.java.net/ example:
+	<!-- ========================= GENERAL DEFINITIONS ========================= -->
+
+	<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
+		<property name="location"><value>classpath:jdbc.properties</value></property>
+	</bean>
+
+	<!-- Message source for this context, loaded from localized "messages_xx" files -->
+	<bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
+		<property name="basename"><value>messages</value></property>										
+	</bean>
+
+
+	<!-- ========================= RESOURCE DEFINITIONS ========================= -->
+  
+	<!-- Local DataSource that works in any environment -->
+	<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
+		<property name="driverClassName"><value>${jdbc.driverClassName}</value></property>
+		<property name="url"><value>${jdbc.url}</value></property>
+		<property name="username"><value>${jdbc.username}</value></property>
+		<property name="password"><value>${jdbc.password}</value></property>
+	</bean>
+
+	<!-- Hibernate SessionFactory -->
+	<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
+		<property name="dataSource"><ref local="dataSource"/></property>
+		<property name="mappingResources">
+			<list>	
+                               	<!-- Write here your list of Hibernate files -->
+				<value>hibernate/catalogue/Article.hbm.xml</value>
+
+			</list>
+		</property>
+		<property name="hibernateProperties">
+			<props>
+				<prop key="hibernate.dialect">${hibernate.dialect}</prop>
+				<prop key="hibernate.show_sql">true</prop>
+				<prop key="hibernate.c3p0.minPoolSize">${hibernate.c3p0.minPoolSize}</prop>
+				<prop key="hibernate.c3p0.maxPoolSize">${hibernate.c3p0.maxPoolSize}</prop>
+				<prop key="hibernate.c3p0.timeout">${hibernate.c3p0.timeout}</prop>
+				<prop key="hibernate.c3p0.max_statement">${hibernate.c3p0.max_statement}</prop>
+				<prop key="hibernate.generate_statistics">true</prop>
+				<prop key="hibernate.cache.use_query_cache">true</prop>
+			</props>
+		</property>
+	</bean>
+
+	<!-- Transaction manager for a single Hibernate SessionFactory (alternative to JTA) -->
+	<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
+		<property name="sessionFactory"><ref local="sessionFactory"/></property>
+	</bean>
+
+
+
+	<!-- ========================= BUSINESS OBJECT DEFINITIONS ========================= -->
+
+	<!-- Petclinic primary business object: Hibernate implementation -->
+	<bean id="WebServiceTarget" class="actualis.web.spring.WebManager"
+	singleton="false">
+		<property name="catalogue"><ref local="catalogueDAO"/></property>
+		<property name="commande"><ref local="commandeDAO"/></property>
+		<property name="clients"><ref local="clientsDAO"/></property>
+	</bean>	
+	
+	<bean id="poolTargetSource"
+		class="org.springframework.aop.target.CommonsPoolTargetSource">
+		<property name="targetBeanName"><value>WebServiceTarget</value></property>
+		<property name="maxSize"><value>5</value></property>
+	</bean>
+	
+	<bean id="businessObject"
+		class="org.springframework.aop.framework.ProxyFactoryBean">
+		<property name="targetSource"><ref local="poolTargetSource"/></property>
+	</bean>
+
+	<!-- Transactional proxy for the Petclinic primary business object -->
+	<bean id="WebService" class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean">
+		<property name="target"><ref local="WebServiceTarget"/></property>
+		<property name="transactionManager"><ref local="transactionManager"/></property>
+			<property name="transactionAttributes">
+			<props>
+				<prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>
+				<prop key="find*">PROPAGATION_REQUIRED,readOnly</prop>
+				<prop key="load*">PROPAGATION_REQUIRED,readOnly</prop>
+				<prop key="store*">PROPAGATION_REQUIRED</prop>
+			</props>
+		</property>
+	</bean>
+	
+	<bean id="catalogueDAO" class="actualis.web.dao.CatalogueDAO">
+		<property name="sessionFactory"><ref local="sessionFactory"/></property>
+	</bean>
+
+	<bean id="commandeDAO" class="actualis.web.dao.CommandeDAO">
+		<property name="sessionFactory"><ref local="sessionFactory"/></property>
+	</bean>
+	
+	<bean id="clientsDAO" class="actualis.web.dao.ClientsDAO">
+		<property name="sessionFactory"><ref local="sessionFactory"/></property>
+	</bean>
+
+	<!-- ========================= WEB INTERCEPTORS DEFINITIONS ========================= -->
+	<bean id="urlMapping"     
+		class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">    
+		<property name="interceptors">
+			<list>
+				<ref bean="openSessionInViewInterceptor"/>
+			</list>
+       </property>
+	</bean>
+	<bean name="openSessionInViewInterceptor"  
+    	class="org.springframework.orm.hibernate3.support.OpenSessionInViewInterceptor">
+		<property name="sessionFactory"><ref bean="sessionFactory"/></property>
+	</bean>	
+
+The last trick is to get the lazy mode working. From one page to another, you are going to loose the session in the
+hibernate objects referenced, so you'll need to update them to reattach them to a session in order to perform operations on them. 
+
+One solution:
+
+1. Create an ordinary many-to-one Cat to Kittens, lazy=true.
+2. Load Cat in page ListCats, but don't touch Kittens.
+3. In page ListCats, instantiate a new Page instance ViewCat.
+4. Set the Cat property for page ViewCat (ie - viewCat.setCat(cat)).
+5. Page ViewCat is activated and begins rendering.
+6. Page ViewCat tries to list this Cat's Kittens, for example in a
+Foreach as in <span jwcid="@Foreach" source="ognl:cat.kittens"
+value="ognl:kitten">.
+
+Page rendering fails with a LazyInitializationException, even though the
+OpenSessionInViewFilter opened a session, since the Cat instance is not
+attached to the open session.
+
+I've gotten around this by adding an attach() method to each of my
+service implementations.  This method invokes getSession().lock( object,
+LockMode.NONE) to reassociate the specified object.  I then manually
+invoke attach() to reassociate the detached objects for the given page.
+For example, in ViewCat.pageBeginRender(), I perform a
+getCatService().attach(getCat()).
+
+Another solution consists in tweaking the Richard Hensley's DataSqueezer trick:
+http://thread.gmane.org/gmane.comp.java.tapestry.user/15398
+
+He creates a custom DataSqueezer that tapestry will invoke automatically.
+Using this technique, a data object is squeezed into a short form (its
+id and classname) when tapestry builds a link or a hidden form field.
+When that url or form field comes back in a later request or form
+submission, tapestry invokes the datasqueezer to unsqueeze it.  The
+unsqueeze operation re loads the dataobject from the database (or cache)
+and hence it is in the current session.
+
+There is also a wiki article on the data squeezer:
+http://wiki.apache.org/jakarta-tapestry/DataSqueezer

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