java.lang.Objectjava.rmi.server.RemoteObject
java.rmi.server.RemoteServer
java.rmi.server.UnicastRemoteObject
java.rmi.activation.ActivationGroup
public abstract class ActivationGroup
An ActivationGroup is responsible for creating new instances of "activatable" objects in its group, informing its ActivationMonitor when either: its object's become active or inactive, or the group as a whole becomes inactive.
An ActivationGroup is initially created in one of several ways:
Only the activator can recreate an ActivationGroup. The activator spawns, as needed, a separate VM (as a child process, for example) for each registered activation group and directs activation requests to the appropriate group. It is implementation specific how VMs are spawned. An activation group is created via the ActivationGroup.createGroup static method. The createGroup method has two requirements on the group to be created: 1) the group must be a concrete subclass of ActivationGroup, and 2) the group must have a constructor that takes two arguments:
When created, the default implementation of ActivationGroup will override the system properties with the properties requested when its ActivationGroupDesc was created, and will set a java.rmi.RMISecurityManager as the default system security manager. If your application requires specific properties to be set when objects are activated in the group, the application should create a special Properties object containing these properties, then create an ActivationGroupDesc with the Properties object, and use ActivationGroup.createGroup before creating any ActivationDescs (before the default ActivationGroupDesc is created). If your application requires the use of a security manager other than java.rmi.RMISecurityManager, in the ActivativationGroupDescriptor properties list you can set java.security.manager property to the name of the security manager you would like to install.
Field Summary |
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Fields inherited from class java.rmi.server. RemoteObject |
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ref |
Constructor Summary | |
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protected |
ActivationGroup
(
ActivationGroupID
groupID) Constructs an activation group with the given activation group identifier. |
Method Summary | |
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protected void |
activeObject
(
ActivationID
id,
MarshalledObject
![]() ![]() This protected method is necessary for subclasses to make the activeObject callback to the group's monitor. |
abstract void |
activeObject
(
ActivationID
id,
Remote
obj) The group's activeObject method is called when an object is exported (either by Activatable object construction or an explicit call to Activatable.exportObject. |
static ActivationGroup |
createGroup
(
ActivationGroupID
id,
ActivationGroupDesc
desc, long incarnation) Create and set the activation group for the current VM. |
static ActivationGroupID |
currentGroupID
() Returns the current activation group's identifier. |
static ActivationSystem |
getSystem
() Returns the activation system for the VM. |
protected void |
inactiveGroup
() This protected method is necessary for subclasses to make the inactiveGroup callback to the group's monitor. |
boolean |
inactiveObject
(
ActivationID
id) The group's inactiveObject method is called indirectly via a call to the Activatable.inactive method. |
static void |
setSystem
(
ActivationSystem
system) Set the activation system for the VM. |
Methods inherited from class java.rmi.server. UnicastRemoteObject |
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clone , exportObject , exportObject , exportObject , unexportObject |
Methods inherited from class java.rmi.server. RemoteServer |
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getClientHost , getLog , setLog |
Methods inherited from class java.rmi.server. RemoteObject |
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equals , getRef , hashCode , toString , toStub |
Methods inherited from class java.lang. Object |
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finalize , getClass , notify , notifyAll , wait , wait , wait |
Methods inherited from interface java.rmi.activation. ActivationInstantiator |
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newInstance |
Constructor Detail |
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protected ActivationGroup(ActivationGroupID groupID) throws RemoteException
Method Detail |
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public boolean inactiveObject(ActivationID id) throws ActivationException, UnknownObjectException, RemoteException
The group's inactiveObject method unexports the remote object from the RMI runtime so that the object can no longer receive incoming RMI calls. An object will only be unexported if the object has no pending or executing calls. The subclass of ActivationGroup must override this method and unexport the object.
After removing the object from the RMI runtime, the group must inform its ActivationMonitor (via the monitor's inactiveObject method) that the remote object is not currently active so that the remote object will be re-activated by the activator upon a subsequent activation request.
This method simply informs the group's monitor that the object is inactive. It is up to the concrete subclass of ActivationGroup to fulfill the additional requirement of unexporting the object.
public abstract void activeObject(ActivationID id, Remote obj) throws ActivationException, UnknownObjectException, RemoteException
public static ActivationGroup createGroup(ActivationGroupID id, ActivationGroupDesc desc, long incarnation) throws ActivationException
The group class specified by the ActivationGroupDesc must be a concrete subclass of ActivationGroup and have a public constructor that takes two arguments: the ActivationGroupID for the group and the MarshalledObject containing the group's initialization data (obtained from the ActivationGroupDesc.
If the group class name specified in the ActivationGroupDesc is null, then this method will behave as if the group descriptor contained the name of the default activation group implementation class.
Note that if your application creates its own custom activation group, a security manager must be set for that group. Otherwise objects cannot be activated in the group. java.rmi.RMISecurityManager is set by default.
If a security manager is already set in the group VM, this method first calls the security manager's checkSetFactory method. This could result in a SecurityException. If your application needs to set a different security manager, you must ensure that the policy file specified by the group's ActivationGroupDesc grants the group the necessary permissions to set a new security manager. (Note: This will be necessary if your group downloads and sets a security manager).
After the group is created, the ActivationSystem is informed that the group is active by calling the activeGroup method which returns the ActivationMonitor for the group. The application need not call activeGroup independently since it is taken care of by this method.
Once a group is created, subsequent calls to the currentGroupID method will return the identifier for this group until the group becomes inactive.
public static ActivationGroupID currentGroupID()
public static void setSystem(ActivationSystem system) throws ActivationException
If there is a security manager, this method first calls the security manager's checkSetFactory method. This could result in a SecurityException.
public static ActivationSystem getSystem() throws ActivationException
protected void activeObject(ActivationID id, MarshalledObject<? extends
Remote
mobj) throwsActivationException> mobj) throws
ActivationException, UnknownObjectException, RemoteException
protected void inactiveGroup() throws UnknownGroupException, RemoteException