Managing the Bean Instance Pool

Configuring Bean Instance Pool Size

You can set the minimum and maximum number of the bean instance pool for session beans, entities, and message-driven beans.

You can configure the bean pool size as follows:

Configuration in the deployment XML overrides the corresponding configuration made using annotations.

Using Annotations

You can specify bean instance pool size for EJB 3.0 session and message-driven beans using the following OC4J-proprietary annotations and their attributes:

@StatelessDeployment attributes:
- maxInstances
- minInstances
For more information about these attributes, see Table A-1.
@StatefulDeployment attributes:
- maxInstances
- maxInstancesThreshold
For more information about these attributes, see Table A-1.

@MessageDrivenDeployment attributes:
- maxInstances
- minInstances
For more information about these attributes, see Table A-3.

Example 31-3 shows how to configure these attributes for an EJB 3.0 stateless session bean using the @StatelessDeployment annotation.

Example 31-3 @StatelessDeployment poolCacheTimeout Attribute

import javax.ejb.Stateless;
import oracle.j2ee.ejb.StatelessDeployment;

@Stateless
@StatelessDeployment(
    maxInstances=10,
    minInstances=3
)
public class HelloWorldBean implements HelloWorld {

    public void sayHello(String name) {
        System.out.println("Hello "+name +" from first EJB3.0");
    }
}

Using Deployment XML

You can specify bean instance pool size for EJB 3.0 session and message-driven beans using the following orion-ejb-jar.xml file elements and their attributes:

<session-deployment> attributes for stateless session beans:
- max-instances
- min-instances
For more information about these attributes, see Table A-1.
<session-deployment> attributes for stateful session beans:
- max-instances
- max-instances-threshold
For more information about these attributes, see Table A-1.

<message-driven-deployment> attributes for message-driven beans:
- max-instances
- min-instances
For more information about these attributes, see Table A-3.

Example 31-4 shows how to configure these attributes for an EJB 3.0 stateless session bean using the orion-ejb-jar.xml file.

Example 31-4 orion-ejb-jar.xml for Bean Instance Pool Size for a Stateless Session Bean

<?xml version="1.0" encoding="utf-8"?>
<orion-ejb-jar
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:noNamespaceSchemaLocation="http://xmlns.oracle.com/oracleas/schema/orion-ejb-jar-10_0.xsd"
    deployment-version="10.1.3.1.0"
    deployment-time="10b1fb5cdd0"
    schema-major-version="10" 
    schema-minor-version="0"
>
    <enterprise-beans>
        <session-deployment
            max-instances="10"
            min-instances="3"
            ...
        >
        </session-deployment>
    ...
    </enterprise-beans>
    ...
</orion-ejb-jar>

If you change this property using this method, you must restart OC4J to apply your changes. Alternatively, you can use Application Server Control Console to modify this parameter dynamically without restarting OC4J (see "Using Oracle Enterprise Manager 10g Application Server Control").

Configuring Bean Instance Pool Timeouts for Session Beans

You can set the maximum amount of time that session beans are cached in the bean instance pool.

You can configure pool timeouts for session beans as follows:

Configuration in the deployment XML overrides the corresponding configuration made using annotations.

Using Annotations

Example 31-5 shows how to configure the bean instance pool timeout for an EJB 3.0 stateless session bean using the @StatelessDeployment annotation poolCacheTimeout attribute.

For more information on this @StatelessDeployment attribute, see Table A-1. For more information on the @StatelessDeployment annotation, see "Configuring OC4J-Proprietary Deployment Options on an EJB 3.0 Session Bean".

Example 31-5 @StatelessDeployment poolCacheTimeout Attribute

import javax.ejb.Stateless;
import oracle.j2ee.ejb.StatelessDeployment;

@Stateless
@StatelessDeployment(
    poolCacheTimeout=90
)
public class HelloWorldBean implements HelloWorld {

    public void sayHello(String name) {
        System.out.println("Hello "+name +" from first EJB3.0");
    }
}

Example 31-6 shows how to configure the bean instance pool timeout for an EJB 3.0 stateful session bean using the @StatefulDeployment annotation timeout attribute.

For more information on this @StatelessDeployment attribute, see Table A-1. For more information on the @StatelessDeployment annotation, see "Configuring OC4J-Proprietary Deployment Options on an EJB 3.0 Session Bean".

Example 31-6 @StatefulDeployment timeout Attribute

import javax.ejb.Stateful
import oracle.j2ee.ejb.StatefulDeployment;

@Stateful
@StatefulDeployment(
    timeout=100
)
public class CartBean implements Cart {

    private ArrayList items;
    ...
}

Using Deployment XML

In the orion-ejb-jar.xml file you set the bean pool timeout with the following attributes of the <session-deployment> element for session beans:

The pool-cache-timeout attribute is applicable to stateless session beans and sets how long to keep stateless sessions cached in the pool. The default is 0 seconds, which means never timeout.

For example, if you wanted to set the pool-cache-timeout to 90 seconds, you would do as follows:
```
<session-deployment ...  pool-cache-timeout="90"
  ...
</session-deployment>
```
The timeout attribute is applicable to stateful session beans and sets how long a stateful session bean can remain inactive before it is removed from the bean instance pool. The default is 1800 seconds.

For example, if you wanted to set the stateful session bean inactivity timeout to 900 seconds, you would do as follows:
```
<session-deployment ...  timeout="900"
  ...
</session-deployment>
```

If you change this property using this method, you must restart OC4J to apply your changes. Alternatively, you can use Application Server Control Console to modify this parameter dynamically without restarting OC4J (see "Using Oracle Enterprise Manager 10g Application Server Control").

Configuring Bean Instance Pool Timeouts for Entity Beans

You can set the maximum amount of time that entities are cached in the bean instance pool.

You can configure pool timeouts for entities as follows:

Using Deployment XML

In the orion-ejb-jar.xml file you set the bean pool timeout with the following attributes of the <entity-deployment> element for entities:

The pool-cache-timeout attribute sets how long entity bean implementation instances are to be kept in the "pooled" (unassigned) state. The default is 60 seconds. Setting this attribute to never means never timeout.

For example, if you wanted to set the pool-cache-timeout for entities to 90 seconds, you would do as follows:
```
<entity-deployment ...  pool-cache-timeout="90"
  ...
</entity-deployment>
```

If you change this property using this method, you must restart OC4J to apply your changes. Alternatively, you can use Application Server Control Console to modify this parameter dynamically without restarting OC4J (see "Using Oracle Enterprise Manager 10g Application Server Control").