Runtime Changes in Deployed Enterprise Beans 

Purpose

This process describes the runtime administration of enterprise beans that are already deployed and running. It is easier and simpler than redeploying an EJB application and does not obstruct the work of clients that already use the deployed EJB application.

Process Flow

When you want to make minor changes to enterprise beans that are already deployed, you can modify them at runtime. The clients that already use this application can therefore continue to use it as the changes are being made. When the bean properties are changed successfully, the whole application is automatically restarted by the system and clients begin to use the updated version.

Use the Runtime tab of the J2EE Engine EJB Container Service to modify the bean properties. For more information, see Changing Enterprise Beans Properties at Runtime.

When you want to make significant changes to the bean properties, or when you want to modify the source code of your enterprise beans, you must redeploy your EJB application.

The runtime changes in enterprise beans that are already deployed differ from the redeployment of enterprise beans in terms of:

·         The process is executed as follows: when changing the bean properties at runtime, the EJB Container updates the application and signals to the Deploy Service that changes have occurred. The EJB application is then restarted by the system. The process of redeployment is controlled by the Deploy Service, which signals to the EJB Container that a new version of the EJB application is available.

·         To modify enterprise bean properties at runtime, you must use the Runtime tab of the EJB Container Service. When modifying an EJB application that you are going to redeploy, you are not limited to using the J2EE Engine tools to modify it. However, we do recommend that you use the SAP Web Application Server tools to redeploy it.

·         The changes at runtime are limited to a few enterprise bean properties. When redeploying, you can modify all enterprise bean properties.

The properties which can be changed at runtime are described in the following tables.

 

Properties Valid for All Types of Enterprise Beans

Property	Description	Notes
Description	Description of the bean and its functions.	Stored in ejb-jar.xml.
Display Name	A short name for the bean. This name is displayed by tools.	Stored in ejb-jar.xml.
JNDI Name	The name under which the bean must be registered in the JNDI and by which it can be looked up.	Stored in ejb-j2ee-engine.xml.
Container Size	The initial size of the EJB Container when the bean is loaded.	Stored in ejb-j2ee-engine.xml.

 

Bean Type-Specific Properties

Stateful Session Beans

Property	Description	Notes
Session Timeout	The period (in seconds) since the session was last used, after which the EJB Container may destroy it. In other words, the EJB Container performs the same operation, as though the bean’s remove() method has been invoked.	The default session timeout is 36000 seconds. Stored in ejb-j2ee-engine.xml.

 

Entity Beans

Property	Description	Notes
Reentrance	Specifies whether the entity bean is reentrant or not.	Stored in ejb-jar.xml.

 

Message-Driven Beans

Property	Description	Notes
Connection Factory Name	The name of the connection factory, which will be used by the EJB Container to obtain connections in order to register the bean as a message listener.	Stored in ejb-j2ee-engine.xml.
Destination Name	The name of the Topic or the Queue to which the bean wants to be subscribed.	Stored in ejb-j2ee-engine.xml.
Message Selector	The JMS message selector, which will be used to determine the messages that the bean will receive.	Stored in ejb-jar.xml.
Destination Type	The type of the destination – Topic or Queue.	Stored in ejb-jar.xml.
Subscription Durability	Defines whether the JMS topic subscription is intended to be durable or nondurable.	Stored in ejb-jar.xml.
Acknowledge Mode	Defines the message acknowledgment semantics that should be used for the onMessage message if the message-driven bean uses bean-managed transaction demarcation.	Stored in ejb-jar.xml.

 

Result

The whole process is transparent to the clients. If the bean properties are changed successfully, the clients continue to use the updated version of the application.

If this process is executed successfully, the system does not save the old state of the application.

If errors occurred (for example, the modified property values are not allowed), the application is not updated and clients continue to use the old version of the application.

This process updates the application’s ejb-jar.xml and the J2EE Engine-specific deployment descriptor   ejb_j2ee_engine.xml.