org.apache.openejb.core.mdb

Class MdbInstanceFactory

java.lang.Object

org.apache.openejb.core.mdb.MdbInstanceFactory

public class MdbInstanceFactory
extends Object

A MdbInstanceFactory creates instances of message driven beans for a single instance. This class differs from other instance managers in OpenEJB as it doesn't do pooling and it creates instances for only a single EJB deployment.

The MdbContainer assumes that the resouce adapter is pooling message endpoints so a second level of pooling in the container would be inefficient. This is true of all known resouce adapters in opensource (ActiveMQ), so if this is a poor assumption for your resource adapter, contact the OpenEJB developers.

This class can optionally limit the number of bean instances and therefore the message endpoints available to the resource adapter.

Constructor Summary

Constructors

Constructor and Description
MdbInstanceFactory(BeanContext beanContext, SecurityService securityService, int instanceLimit) Creates a MdbInstanceFactory for a single specific deployment.

Method Summary

Methods

Modifier and Type	Method and Description
Object	createInstance(boolean ignoreInstanceCount) Creates a new mdb instance preforming all necessary lifecycle callbacks
void	freeInstance(Instance instance, boolean ignoredInstanceCount) Frees an instance no longer needed by the resource adapter.
int	getInstanceCount() Gets the current number of created instances.
int	getInstanceLimit() Gets the maximal number of instances that can exist at any time.
Object	recreateInstance(Object bean) Recreates a bean instance that has thrown a system exception.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MdbInstanceFactory

public MdbInstanceFactory(BeanContext beanContext,
                  SecurityService securityService,
                  int instanceLimit)
                   throws OpenEJBException

Creates a MdbInstanceFactory for a single specific deployment.

Parameters:

beanContext - the deployment for which instances will be created

securityService - the transaction manager for this container system

instanceLimit - the maximal number of instances or <= 0 if unlimited

Throws:

OpenEJBException

Method Detail

getInstanceLimit

public int getInstanceLimit()

Gets the maximal number of instances that can exist at any time.

Returns:

the maximum number of instances or <= 0 if unlimitied

getInstanceCount

public int getInstanceCount()

Gets the current number of created instances.

Returns:

the current number of instances created

createInstance

public Object createInstance(boolean ignoreInstanceCount)
                      throws javax.resource.spi.UnavailableException

Creates a new mdb instance preforming all necessary lifecycle callbacks

Parameters:

ignoreInstanceCount -

Returns:

a new message driven bean instance

Throws:

javax.resource.spi.UnavailableException - if the instance limit has been exceeded or if an exception occurs while creating the bean instance

freeInstance

public void freeInstance(Instance instance,
                boolean ignoredInstanceCount)

Frees an instance no longer needed by the resource adapter. This method makes all the necessary lifecycle callbacks and decrements the instance count. This method should not be used to disposed of beans that have thrown a system exception. Instead the discardInstance method should be called.

Parameters:

instance - the bean instance to free

ignoredInstanceCount -

recreateInstance

public Object recreateInstance(Object bean)
                        throws javax.resource.spi.UnavailableException

Recreates a bean instance that has thrown a system exception. As required by the EJB specification, lifecycle callbacks are not invoked. To normally free a bean instance call the freeInstance method.

Parameters:

bean - the bean instance to discard

Returns:

the new replacement bean instance

Throws:

javax.resource.spi.UnavailableException