Control Serialization
Overview

This document describes control serialization. Typically control serialization is initiated by the runtime container; however, serialization may also be initiated programmatically by a controls developer. For either case the process described in the Serialization Steps section of this document are the same.

isTransient

When developing a control which does not need its state serialized, the isTransient attribute of the ControlImplementation annotation may be set to true. If not explicitly set isTransient will default to false.

@ControlImplementation(isTransient=true) public class MyControlImpl implements MyControl { . . . }

If isTransient is set to true the control implementation will not be serialized. After deserialization a new instance of the control implementation will be instantiated by the controls framework upon the first method invocation on that control.

XML vs Java Serialization

Beehive controls support standard Java serialization as well as XML serialization. All of the necessary PersistenceDelegate implementations already exist in the controls framework to support XML serialization using the XMLEncoder and XMLDecoder classes.

Serialization Steps

Before serialization can occur, the current ResourceContext must be ended for all controls within the ControlContainerContext (CCC). Typically this is accomplished by a call to the CCC's endContext() method. The endContext() method causes an onRelease resource event to be fired to all controls within the CCC. Any controls with onRelease event listeners then have the opportunity to release any resources (such as JDBC connections, JNDI contexts, sessions, etc) before serialization occurs.

During deserialization resources can be reacquired by the control once a new ResourceContext has been established by the CCC. Each control then gets notified with on onAcquire resource event.

The CCC performs a number of actions on serialization:

  1. Service providers ( BeanContextServiceProvider) registered with the ControlBeanContextServicesSupport instance are serialized, including any registered BeanContextServicesListeners which have been registered for those services.
  2. Next the children of the CCC are serialized. Children of the CCC include ControlBeans as well as each ControlBean's ControlBeanContext. Any registered BeanContextMembershipListeners are also serialized.
  3. Each ControlBean contains a reference to a control implementation class which gets serialized as well (unless the implementation's isTransient annotation attribute is set to true, which case it will not be serialized).
  4. The ControlBean contains the control's property state which gets serialized as part of the ControlBean.