RO/RW pattern and Cache invalidation

[navjot_m]

Hello,

I am trying to implement the RO/RW pattern presented as a case study in the JBoss clustering documentation in "Cache Invalidation" chapter. I have attached the relevant code snippets. The DomainClassROBean is the read only version for DomainClassBean. What I notice when I run the "findAll" method are the SQL statements:

First time it is run:

2003-10-16 18:44:09,347 DEBUG [org.jboss.ejb.plugins.cmp.jdbc.JDBCEJBQLQuery.DomainClassRO.findAll] Executing SQL: SELECT t0_dc.id FROM DomainClass t0_dc
2003-10-16 18:44:09,382 DEBUG [org.jboss.ejb.plugins.cmp.jdbc.JDBCLoadEntityCommand.DomainClassRO] Executing SQL: SELECT id,version, name, type FROM DomainClass WHERE (id=?) OR (id=?) OR (id=?) OR (id=?) OR (id=?) OR (id=?) OR (id=?)

And for every subsequent call, the following:

2003-10-16 18:44:09,587 DEBUG [org.jboss.ejb.plugins.cmp.jdbc.JDBCEJBQLQuery.DomainClassRO.findAll] Executing SQL: SELECT t0_dc.id FROM DomainClass t0_dc

My question is, why does it call the SQL at all second time if this is a cached bean with all attributes read only! I am not using clustering.

Thanks,
Navjot

=================================

The form is not letting me attach, so I am including the relevant code in the post:

jboss.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE jboss PUBLIC "-//JBoss//DTD JBOSS 3.2//EN" "http://www.jboss.org/j2ee/dtd/jboss_3_2.dtd">



<enterprise-beans>



<ejb-name>Domain</ejb-name>
<local-jndi-name>ejb/DomainHomeLocal</local-jndi-name>
<configuration-name>Standard CMP 2.x EntityBean with cache invalidation</configuration-name>
<cache-invalidation>true</cache-invalidation>
<cache-invalidation-config>
<invalidation-group-name>DomainCacheGroup</invalidation-group-name>
</cache-invalidation-config>

<method-attributes>
</method-attributes>



<ejb-name>DomainRO</ejb-name>
<local-jndi-name>ejb/DomainROHomeLocal</local-jndi-name>
<read-only>true</read-only>
<configuration-name>Standard CMP 2.x EntityBean with cache invalidation</configuration-name>
<cache-invalidation>true</cache-invalidation>
<cache-invalidation-config>
<invalidation-group-name>DomainCacheGroup</invalidation-group-name>
</cache-invalidation-config>

<method-attributes>
</method-attributes>



<ejb-name>DomainClassRO</ejb-name>
<local-jndi-name>ejb/DomainClassROHomeLocal</local-jndi-name>
<read-only>true</read-only>
<configuration-name>Standard CMP 2.x EntityBean with cache invalidation</configuration-name>
<cache-invalidation>true</cache-invalidation>
<cache-invalidation-config>
<invalidation-group-name>DomainClassCacheGroup</invalidation-group-name>
</cache-invalidation-config>

<method-attributes>
</method-attributes>



<ejb-name>DomainClass</ejb-name>
<local-jndi-name>ejb/DomainClassHomeLocal</local-jndi-name>
<configuration-name>Standard CMP 2.x EntityBean with cache invalidation</configuration-name>
<cache-invalidation>true</cache-invalidation>
<cache-invalidation-config>
<invalidation-group-name>DomainClassCacheGroup</invalidation-group-name>
</cache-invalidation-config>

<method-attributes>

<method-name>get*</method-name>
<read-only>true</read-only>

</method-attributes>


</enterprise-beans>

<resource-managers>
</resource-managers>



====================================

jbosscmp-jdbc.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE jbosscmp-jdbc PUBLIC "-//JBoss//DTD JBOSSCMP-JDBC 3.2//EN" "http://www.jboss.org/j2ee/dtd/jbosscmp-jdbc_3_2.dtd">

<jbosscmp-jdbc>



<enterprise-beans>




<ejb-name>Domain</ejb-name>
<table-name>Domain</table-name>

<cmp-field>
<field-name>id</field-name>
<column-name>id</column-name>

<auto-increment/>
</cmp-field>
<cmp-field>
<field-name>version</field-name>
<column-name>version</column-name>

</cmp-field>
<cmp-field>
<field-name>name</field-name>
<column-name>name</column-name>

</cmp-field>
<cmp-field>
<field-name>state</field-name>
<column-name>state</column-name>

</cmp-field>

<entity-command name="mysql-get-generated-keys">
</entity-command>
<!-- jboss 3.2 features -->
<!-- optimistic locking does not express the exclusions needed -->



<ejb-name>DomainRO</ejb-name>
<read-only>true</read-only>
<table-name>Domain</table-name>

<cmp-field>
<field-name>id</field-name>
<column-name>id</column-name>

</cmp-field>
<cmp-field>
<field-name>version</field-name>
<column-name>version</column-name>

</cmp-field>
<cmp-field>
<field-name>name</field-name>
<column-name>name</column-name>

</cmp-field>
<cmp-field>
<field-name>state</field-name>
<column-name>state</column-name>

</cmp-field>

<!-- jboss 3.2 features -->
<!-- optimistic locking does not express the exclusions needed -->


<ejb-name>DomainClassRO</ejb-name>
<read-only>true</read-only>
<table-name>DomainClass</table-name>

<cmp-field>
<field-name>id</field-name>
<column-name>id</column-name>

</cmp-field>
<cmp-field>
<field-name>version</field-name>
<column-name>version</column-name>

</cmp-field>
<cmp-field>
<field-name>name</field-name>
<column-name>name</column-name>

</cmp-field>
<cmp-field>
<field-name>type</field-name>
<column-name>type</column-name>

</cmp-field>

<!-- jboss 3.2 features -->
<!-- optimistic locking does not express the exclusions needed -->


<ejb-name>DomainClass</ejb-name>
<table-name>DomainClass</table-name>

<cmp-field>
<field-name>id</field-name>
<column-name>id</column-name>

<auto-increment/>
</cmp-field>
<cmp-field>
<field-name>version</field-name>
<column-name>version</column-name>

</cmp-field>
<cmp-field>
<field-name>name</field-name>
<column-name>name</column-name>

</cmp-field>
<cmp-field>
<field-name>type</field-name>
<column-name>type</column-name>

</cmp-field>

<entity-command name="mysql-get-generated-keys">
</entity-command>
<!-- jboss 3.2 features -->
<!-- optimistic locking does not express the exclusions needed -->


</enterprise-beans>


<ejb-relation>
<ejb-relation-name>DomainClass-Domain</ejb-relation-name>

<ejb-relationship-role>
<ejb-relationship-role-name>Domain-is_of_class-DomainClass</ejb-relationship-role-name>
<key-fields/>

</ejb-relationship-role>
<ejb-relationship-role>
<ejb-relationship-role-name>DomainClass-has_domains-Domains</ejb-relationship-role-name>
<key-fields>
<key-field>
<field-name>id</field-name>
<column-name>domainClassId</column-name>
</key-field>
</key-fields>

</ejb-relationship-role>
</ejb-relation>
<ejb-relation>
<ejb-relation-name>DomainClassRO-DomainRO</ejb-relation-name>

<ejb-relationship-role>
<ejb-relationship-role-name>DomainRO-is_of_class-DomainClassRO</ejb-relationship-role-name>
<key-fields/>

</ejb-relationship-role>
<ejb-relationship-role>
<ejb-relationship-role-name>DomainClassRO-has_domains-DomainsRO</ejb-relationship-role-name>
<key-fields>
<key-field>
<field-name>id</field-name>
<column-name>domainClassId</column-name>
</key-field>
</key-fields>

</ejb-relationship-role>
</ejb-relation>


</jbosscmp-jdbc>

=====================================

ejb-jar.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE ejb-jar PUBLIC "-//Sun Microsystems, Inc.//DTD Enterprise JavaBeans 2.0//EN" "http://java.sun.com/dtd/ejb-jar_2_0.dtd">

<ejb-jar >

<![CDATA[No Description.]]>
<display-name>Generated by XDoclet</display-name>

<enterprise-beans>

<!-- Entity Beans -->

<![CDATA[Entity bean representing the domain.]]>

<ejb-name>Domain</ejb-name>

<local-home>com.CapitalOne.COPOSEDiC.ejb.domain.interfaces.DomainLocalHome</local-home>
com.CapitalOne.COPOSEDiC.ejb.domain.interfaces.DomainLocal

<ejb-class>com.CapitalOne.COPOSEDiC.ejb.domain.DomainBean</ejb-class>
<persistence-type>Container</persistence-type>
<prim-key-class>java.lang.Long</prim-key-class>
False
<cmp-version>2.x</cmp-version>
<abstract-schema-name>Domain</abstract-schema-name>
<cmp-field >
<![CDATA[Unique id for the parameter.]]>
<field-name>id</field-name>
</cmp-field>
<cmp-field >
<![CDATA[Version number]]>
<field-name>version</field-name>
</cmp-field>
<cmp-field >
<![CDATA[Name of parameter.]]>
<field-name>name</field-name>
</cmp-field>
<cmp-field >
<![CDATA[State of the domain]]>
<field-name>state</field-name>
</cmp-field>
<primkey-field>id</primkey-field>

<ejb-local-ref >
<ejb-ref-name>ejb/DomainClassLocal</ejb-ref-name>
<ejb-ref-type>Entity</ejb-ref-type>
<local-home>com.CapitalOne.COPOSEDiC.ejb.domain.interfaces.DomainClassLocalHome</local-home>
com.CapitalOne.COPOSEDiC.ejb.domain.interfaces.DomainClassLocal
<ejb-link>DomainClass</ejb-link>
</ejb-local-ref>

<!-- Write a file named ejb-finders-DomainBean.xml if you want to define extra finders. -->


<![CDATA[Entity bean representing the (read-only) domain.]]>

<ejb-name>DomainRO</ejb-name>

<local-home>com.CapitalOne.COPOSEDiC.ejb.domain.interfaces.RO.DomainROLocalHome</local-home>
com.CapitalOne.COPOSEDiC.ejb.domain.interfaces.RO.DomainROLocal

<ejb-class>com.CapitalOne.COPOSEDiC.ejb.domain.RO.DomainROBean</ejb-class>
<persistence-type>Container</persistence-type>
<prim-key-class>java.lang.Long</prim-key-class>
False
<cmp-version>2.x</cmp-version>
<abstract-schema-name>DomainRO</abstract-schema-name>
<cmp-field >
<![CDATA[Unique id for the parameter.]]>
<field-name>id</field-name>
</cmp-field>
<cmp-field >
<![CDATA[Version number]]>
<field-name>version</field-name>
</cmp-field>
<cmp-field >
<![CDATA[Name of parameter.]]>
<field-name>name</field-name>
</cmp-field>
<cmp-field >
<![CDATA[State of the domain]]>
<field-name>state</field-name>
</cmp-field>
<primkey-field>id</primkey-field>


<query-method>
<method-name>findAll</method-name>
<method-params>
</method-params>
</query-method>
<ejb-ql><![CDATA[SELECT OBJECT(d) FROM DomainRO AS d]]></ejb-ql>

<!-- Write a file named ejb-finders-DomainROBean.xml if you want to define extra finders. -->



<![CDATA[Entity bean representing the (read only) domain class.]]>

<ejb-name>DomainClassRO</ejb-name>

<local-home>com.CapitalOne.COPOSEDiC.ejb.domain.interfaces.RO.DomainClassROLocalHome</local-home>
com.CapitalOne.COPOSEDiC.ejb.domain.interfaces.RO.DomainClassROLocal

<ejb-class>com.CapitalOne.COPOSEDiC.ejb.domain.RO.DomainClassROBean</ejb-class>
<persistence-type>Container</persistence-type>
<prim-key-class>java.lang.Long</prim-key-class>
False
<cmp-version>2.x</cmp-version>
<abstract-schema-name>DomainClassRO</abstract-schema-name>
<cmp-field >
<![CDATA[Unique id for the domain class.]]>
<field-name>id</field-name>
</cmp-field>
<cmp-field >
<![CDATA[Version number]]>
<field-name>version</field-name>
</cmp-field>
<cmp-field >
<![CDATA[Name of domain class.]]>
<field-name>name</field-name>
</cmp-field>
<cmp-field >
<![CDATA[Type of the domain class.]]>
<field-name>type</field-name>
</cmp-field>
<primkey-field>id</primkey-field>


<query-method>
<method-name>findAll</method-name>
<method-params>
</method-params>
</query-method>
<ejb-ql><![CDATA[SELECT OBJECT(dc) FROM DomainClassRO AS dc]]></ejb-ql>


<query-method>
<method-name>findByName</method-name>
<method-params>
<method-param>java.lang.String</method-param>
</method-params>
</query-method>
<ejb-ql><![CDATA[SELECT OBJECT(dc) FROM DomainClassRO AS dc WHERE dc.name = ?1]]></ejb-ql>

<!-- Write a file named ejb-finders-DomainClassROBean.xml if you want to define extra finders. -->



<![CDATA[Entity bean representing the domain class.]]>

<ejb-name>DomainClass</ejb-name>

<local-home>com.CapitalOne.COPOSEDiC.ejb.domain.interfaces.DomainClassLocalHome</local-home>
com.CapitalOne.COPOSEDiC.ejb.domain.interfaces.DomainClassLocal

<ejb-class>com.CapitalOne.COPOSEDiC.ejb.domain.DomainClassBean</ejb-class>
<persistence-type>Container</persistence-type>
<prim-key-class>java.lang.Long</prim-key-class>
False
<cmp-version>2.x</cmp-version>
<abstract-schema-name>DomainClass</abstract-schema-name>
<cmp-field >
<![CDATA[Unique id for the domain class.]]>
<field-name>id</field-name>
</cmp-field>
<cmp-field >
<![CDATA[Version number]]>
<field-name>version</field-name>
</cmp-field>
<cmp-field >
<![CDATA[Name of domain class.]]>
<field-name>name</field-name>
</cmp-field>
<cmp-field >
<![CDATA[Type of the domain class.]]>
<field-name>type</field-name>
</cmp-field>
<primkey-field>id</primkey-field>

<!-- Write a file named ejb-finders-DomainClassBean.xml if you want to define extra finders. -->


</enterprise-beans>

<!-- Relationships -->

<ejb-relation >
<ejb-relation-name>DomainClass-Domain</ejb-relation-name>

<ejb-relationship-role >
<ejb-relationship-role-name>Domain-is_of_class-DomainClass</ejb-relationship-role-name>
Many
<relationship-role-source >
<ejb-name>Domain</ejb-name>
</relationship-role-source>
<cmr-field >
<cmr-field-name>domainClass</cmr-field-name>
</cmr-field>
</ejb-relationship-role>

<ejb-relationship-role >
<ejb-relationship-role-name>DomainClass-has_domains-Domains</ejb-relationship-role-name>
One
<relationship-role-source >
<ejb-name>DomainClass</ejb-name>
</relationship-role-source>
<cmr-field >
<cmr-field-name>domains</cmr-field-name>
<cmr-field-type>java.util.Collection</cmr-field-type>
</cmr-field>
</ejb-relationship-role>

</ejb-relation>
<ejb-relation >
<ejb-relation-name>DomainClassRO-DomainRO</ejb-relation-name>

<ejb-relationship-role >
<ejb-relationship-role-name>DomainRO-is_of_class-DomainClassRO</ejb-relationship-role-name>
Many
<relationship-role-source >
<ejb-name>DomainRO</ejb-name>
</relationship-role-source>
<cmr-field >
<cmr-field-name>domainClass</cmr-field-name>
</cmr-field>
</ejb-relationship-role>

<ejb-relationship-role >
<ejb-relationship-role-name>DomainClassRO-has_domains-DomainsRO</ejb-relationship-role-name>
One
<relationship-role-source >
<ejb-name>DomainClassRO</ejb-name>
</relationship-role-source>
<cmr-field >
<cmr-field-name>domains</cmr-field-name>
<cmr-field-type>java.util.Collection</cmr-field-type>
</cmr-field>
</ejb-relationship-role>

</ejb-relation>


<!-- Assembly Descriptor -->
<assembly-descriptor >
</assembly-descriptor>

</ejb-jar>

=================================

DomainClassBean.java:

/*
* Created on Sep 11, 2003
*
*/
package com.CapitalOne.COPOSEDiC.ejb.domain;

import java.util.Collection;
import javax.ejb.*;
import com.CapitalOne.COPOSEDiC.DTO.DomainClassDTO;

/**
* Entity bean representing the domain class.
*
* @author nmar3921
*
* @ejb.bean
* name = "DomainClass"
* schema = "DomainClass"
* local-jndi-name = "ejb/DomainClassHomeLocal"
* view-type = "local"
* type = "CMP"
* cmp-version = "2.x"
* primkey-field = "id"
* @ejb.persistence
* table-name = "DomainClass"
*
* @jboss.entity-command
* name = "mysql-get-generated-keys"
* @jboss.container-configuration
* name = "Standard CMP 2.x EntityBean with cache invalidation"
* @jboss.cache-invalidation
* value = "true"
* @jboss.cache-invalidation-config
* invalidation-group-name = "DomainClassCacheGroup"
* @jboss.method-attributes
* pattern = "get*"
* read-only = "true"
*/
public abstract class DomainClassBean implements EntityBean {

/** Reference to EntityContext */
protected EntityContext entityContext = null;

/*
***** CREATE CREATE CREATE *****
*/

/**
* Create a new domain class entity.
*
* @ejb.create-method
*/
public Long ejbCreate(DomainClassDTO domainClassDTO) throws CreateException {
setName(domainClassDTO.getName());
setType(domainClassDTO.getType());
setVersion(new Integer(1));
return null;
}

/**
* Create a new domain class entity.
*
*/
public void ejbPostCreate(DomainClassDTO domainClassDTO) throws CreateException {

}

/*
***** CMP CMP CMP CMP CMP *****
*/

/**
* Unique id for the domain class.
*
* @ejb.persistence
* column-name = "id"
* @ejb.pk-field
* @ejb.interface-method
*
* @jboss.persistence
* auto-increment = "true"
*/
public abstract Long getId();

/**
*
*/
public abstract void setId(Long id);

/**
* Version number
*
* @ejb.persistence
* column-name = "version"
* @ejb.interface-method
*/
public abstract Integer getVersion();

/**
* Version number
*
* @param version
*
* @ejb.interface-method
*/
public abstract void setVersion(Integer version);

/**
* Name of domain class.
*
* @ejb.persistence
* column-name = "name"
* @ejb.interface-method
*/
public abstract String getName();

/**
* Name of domain class.
*
* @ejb.interface-method
*/
public abstract void setName(String name);

/**
* Type of the domain class.
*
* @return
*
* @ejb.persistence
* column-name = "type"
* @ejb.interface-method
*/
public abstract String getType();

/**
* Type of domain class.
*
* @param type
*
* @ejb.interface-method
*/
public abstract void setType(String type);

/*
***** CMR CMR CMR CMR CMR *****
*/

/**
* Domains in this domain class.
*
* @ejb.relation
* name = "DomainClass-Domain"
* role-name = "DomainClass-has_domains-Domains"
*
* @ejb.interface-method
*/
public abstract Collection getDomains();

/**
* Domains in this domain class.
*
* @param domains
*
* @ejb.interface-method
*/
public abstract void setDomains(Collection domains);

/*
***** METHODS METHODS METHODS METHODS *****
*/

/**
* @ejb.interface-method
*/
public void incrementVersion(){
this.setVersion(new Integer(this.getVersion().intValue()+1));
}

/*
* EJB LIFE_CYCLE METHODS
*/

public void ejbActivate() {
}

public void ejbLoad() {
}

public void ejbPassivate() {
}

public void ejbRemove() {
}

public void ejbStore() {
}

public void setEntityContext(EntityContext ctx) {
entityContext = ctx;
}

public void unsetEntityContext() {
}
}

===============================

DomainClassROBean.java:

/*
* Created on Sep 11, 2003
*
*/
package com.CapitalOne.COPOSEDiC.ejb.domain.RO;

import java.util.Collection;
import javax.ejb.*;

/**
* Entity bean representing the (read only) domain class.
*
* @author nmar3921
*
* @ejb.bean
* name = "DomainClassRO"
* schema = "DomainClassRO"
* local-jndi-name = "ejb/DomainClassROHomeLocal"
* view-type = "local"
* type = "CMP"
* cmp-version = "2.x"
* primkey-field = "id"
* @ejb.persistence
* table-name = "DomainClass"
* @ejb.finder
* signature = "java.util.Collection findAll()"
* query = "SELECT OBJECT(dc) FROM DomainClassRO AS dc"
* @ejb.finder
* signature = "com.CapitalOne.COPOSEDiC.ejb.domain.interfaces.RO.DomainClassROLocal findByName(java.lang.String name)"
* query = "SELECT OBJECT(dc) FROM DomainClassRO AS dc WHERE dc.name = ?1"
*
* @jboss.persistence
* read-only = "true"
* @jboss.read-only
* read-only = "true"
* @jboss.container-configuration
* name = "Standard CMP 2.x EntityBean with cache invalidation"
* @jboss.cache-invalidation
* value = "true"
* @jboss.cache-invalidation-config
* invalidation-group-name = "DomainClassCacheGroup"
*/
public abstract class DomainClassROBean implements EntityBean {

/** Reference to EntityContext */
protected EntityContext entityContext = null;

/*
***** CREATE CREATE CREATE *****
*/

/**
* Create a new domain class entity.
*
* @ejb.create-method
*/
public Long ejbCreate() throws CreateException {
return null;
}

/**
* Create a new domain class entity.
*
*/
public void ejbPostCreate() throws CreateException {
}

/*
***** CMP CMP CMP CMP CMP *****
*/

/**
* Unique id for the domain class.
*
* @ejb.persistence
* column-name = "id"
* @ejb.pk-field
* @ejb.interface-method
*/
public abstract Long getId();

/**
*
*/
public abstract void setId(Long id);

/**
* Version number
*
* @ejb.persistence
* column-name = "version"
* @ejb.interface-method
*/
public abstract Integer getVersion();

/**
* Version number
*
* @param version
*/
public abstract void setVersion(Integer version);

/**
* Name of domain class.
*
* @ejb.persistence
* column-name = "name"
* @ejb.interface-method
*/
public abstract String getName();

/**
* Name of domain class.
*/
public abstract void setName(String name);

/**
* Type of the domain class.
*
* @return
*
* @ejb.persistence
* column-name = "type"
* @ejb.interface-method
*/
public abstract String getType();

/**
* Type of domain class.
*
* @param type
*/
public abstract void setType(String type);

/*
***** CMR CMR CMR CMR CMR *****
*/

/**
* Domains in this domain class.
*
* @ejb.relation
* name = "DomainClassRO-DomainRO"
* role-name = "DomainClassRO-has_domains-DomainsRO"
*
* @ejb.interface-method
*/
public abstract Collection getDomains();

/**
* Domains in this domain class.
*
* @param domains
*/
public abstract void setDomains(Collection domains);

/*
* EJB LIFE_CYCLE METHODS
*/

public void ejbActivate() {
}

public void ejbLoad() {
}

public void ejbPassivate() {
}

public void ejbRemove() {
}

public void ejbStore() {
}

public void setEntityContext(EntityContext ctx) {
entityContext = ctx;
}

public void unsetEntityContext() {
}
}

[nraghuram]

The findAll method will query the database every time because the container does not cache finder query results. But the loadEntity command is called only when the entity does not exist in the cache or the cached entity is invalid.
hth
raghu

[navjot_m]

But isn't is faster to run the query on the cached data instead of the database. I understand it does not cache the finder query results, but why is it going to the database to run the query? Is this going to happen for all finder methods? (Find by Name etc.) because if that is the case, it defeats half the purpose of caching! Is there any way to set up JBoss to run the query on the cached data set?

Thanks.

[nraghuram]

afaik it queries the database every time. querying the cached data is not so simple because the cache will usually be a subset of the db data.