Activatable (Java Platform SE 8 )
Keywords: java.rmi.activation.Activatable class
Date: 2018-07-01

compact2, compact3
java.rmi.activation

## Class Activatable

- java.lang.Object
- - java.rmi.server.RemoteObject
  - - java.rmi.server.RemoteServer
    - - java.rmi.activation.Activatable

- All Implemented Interfaces:
    Serializable, Remote

      public abstract class Activatable
      extends RemoteServer

  The `Activatable` class provides support for remote objects that require persistent access over time and that can be activated by the system.

  For the constructors and static `exportObject` methods, the stub for a remote object being exported is obtained as described in `UnicastRemoteObject`.

  An attempt to serialize explicitly an instance of this class will fail.

  Since:
    1.2

- - ### Field Summary

    - ### Fields inherited from class java.rmi.server.RemoteObject

      `ref`

  - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `Activatable(ActivationID id, int port)` Constructor used to activate/export the object on a specified port.
    `protected` | `Activatable(ActivationID id, int port, RMIClientSocketFactory csf, RMIServerSocketFactory ssf)` Constructor used to activate/export the object on a specified port.
    `protected` | `Activatable(String location, MarshalledObject<?> data, boolean restart, int port)` Constructs an activatable remote object by registering an activation descriptor (with the specified location, data, and restart mode) for this object, and exporting the object with the specified port.
    `protected` | `Activatable(String location, MarshalledObject<?> data, boolean restart, int port, RMIClientSocketFactory csf, RMIServerSocketFactory ssf)` Constructs an activatable remote object by registering an activation descriptor (with the specified location, data, and restart mode) for this object, and exporting the object with the specified port, and specified client and server socket factories.

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static Remote` | `exportObject(Remote obj, ActivationID id, int port)` Export the activatable remote object to the RMI runtime to make the object available to receive incoming calls.
    `static Remote` | `exportObject(Remote obj, ActivationID id, int port, RMIClientSocketFactory csf, RMIServerSocketFactory ssf)` Export the activatable remote object to the RMI runtime to make the object available to receive incoming calls.
    `static ActivationID` | `exportObject(Remote obj, String location, MarshalledObject<?> data, boolean restart, int port)` Registers an activation descriptor (with the specified location, data, and restart mode) for the specified object, and exports that object with the specified port.
    `static ActivationID` | `exportObject(Remote obj, String location, MarshalledObject<?> data, boolean restart, int port, RMIClientSocketFactory csf, RMIServerSocketFactory ssf)` Registers an activation descriptor (with the specified location, data, and restart mode) for the specified object, and exports that object with the specified port, and the specified client and server socket factories.
    `protected ActivationID` | `getID()` Returns the object's activation identifier.
    `static boolean` | `inactive(ActivationID id)` Informs the system that the object with the corresponding activation `id` is currently inactive.
    `static Remote` | `register(ActivationDesc desc)` Register an object descriptor for an activatable remote object so that is can be activated on demand.
    `static boolean` | `unexportObject(Remote obj, boolean force)` Remove the remote object, obj, from the RMI runtime.
    `static void` | `unregister(ActivationID id)` Revokes previous registration for the activation descriptor associated with `id`.

    - ### Methods inherited from class java.rmi.server.RemoteServer

      `getClientHost, getLog, setLog`

    - ### Methods inherited from class java.rmi.server.RemoteObject

      `equals, getRef, hashCode, toString, toStub`

    - ### Methods inherited from class java.lang.Object

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### Constructor Detail

    - #### Activatable

          protected Activatable(String location,
                                MarshalledObject<?> data,
                                boolean restart,
                                int port)
                         throws ActivationException,
                                RemoteException

      Constructs an activatable remote object by registering an activation descriptor (with the specified location, data, and restart mode) for this object, and exporting the object with the specified port.

      Note: Using the `Activatable` constructors that both register and export an activatable remote object is strongly discouraged because the actions of registering and exporting the remote object are not guaranteed to be atomic. Instead, an application should register an activation descriptor and export a remote object separately, so that exceptions can be handled properly.

      This method invokes the `exportObject` method with this object, and the specified location, data, restart mode, and port. Subsequent calls to `getID()` will return the activation identifier returned from the call to `exportObject`.

      Parameters:
        `location` - the location for classes for this object
        `data` - the object's initialization data
        `port` - the port on which the object is exported (an anonymous port is used if port=0)
        `restart` - if true, the object is restarted (reactivated) when either the activator is restarted or the object's activation group is restarted after an unexpected crash; if false, the object is only activated on demand. Specifying `restart` to be `true` does not force an initial immediate activation of a newly registered object; initial activation is lazy.
      Throws:
        `ActivationException` - if object registration fails.
        `RemoteException` - if either of the following fails: a) registering the object with the activation system or b) exporting the object to the RMI runtime.
        `UnsupportedOperationException` - if and only if activation is not supported by this implementation.
      Since:
        1.2

    - #### Activatable

          protected Activatable(String location,
                                MarshalledObject<?> data,
                                boolean restart,
                                int port,
                                RMIClientSocketFactory csf,
                                RMIServerSocketFactory ssf)
                         throws ActivationException,
                                RemoteException

      Constructs an activatable remote object by registering an activation descriptor (with the specified location, data, and restart mode) for this object, and exporting the object with the specified port, and specified client and server socket factories.

      Note: Using the `Activatable` constructors that both register and export an activatable remote object is strongly discouraged because the actions of registering and exporting the remote object are not guaranteed to be atomic. Instead, an application should register an activation descriptor and export a remote object separately, so that exceptions can be handled properly.

      This method invokes the `exportObject` method with this object, and the specified location, data, restart mode, port, and client and server socket factories. Subsequent calls to `getID()` will return the activation identifier returned from the call to `exportObject`.

      Parameters:
        `location` - the location for classes for this object
        `data` - the object's initialization data
        `restart` - if true, the object is restarted (reactivated) when either the activator is restarted or the object's activation group is restarted after an unexpected crash; if false, the object is only activated on demand. Specifying `restart` to be `true` does not force an initial immediate activation of a newly registered object; initial activation is lazy.
        `port` - the port on which the object is exported (an anonymous port is used if port=0)
        `csf` - the client-side socket factory for making calls to the remote object
        `ssf` - the server-side socket factory for receiving remote calls
      Throws:
        `ActivationException` - if object registration fails.
        `RemoteException` - if either of the following fails: a) registering the object with the activation system or b) exporting the object to the RMI runtime.
        `UnsupportedOperationException` - if and only if activation is not supported by this implementation.
      Since:
        1.2

    - #### Activatable

          protected Activatable(ActivationID id,
                                int port)
                         throws RemoteException

      Constructor used to activate/export the object on a specified port. An "activatable" remote object must have a constructor that takes two arguments:
      - the object's activation identifier (`ActivationID`), and
      - the object's initialization data (a `MarshalledObject`).

      A concrete subclass of this class must call this constructor when it is activated via the two parameter constructor described above. As a side-effect of construction, the remote object is "exported" to the RMI runtime (on the specified `port`) and is available to accept incoming calls from clients.

      Parameters:
        `id` - activation identifier for the object
        `port` - the port number on which the object is exported
      Throws:
        `RemoteException` - if exporting the object to the RMI runtime fails
        `UnsupportedOperationException` - if and only if activation is not supported by this implementation
      Since:
        1.2

    - #### Activatable

          protected Activatable(ActivationID id,
                                int port,
                                RMIClientSocketFactory csf,
                                RMIServerSocketFactory ssf)
                         throws RemoteException

      Constructor used to activate/export the object on a specified port. An "activatable" remote object must have a constructor that takes two arguments:
      - the object's activation identifier (`ActivationID`), and
      - the object's initialization data (a `MarshalledObject`).

      A concrete subclass of this class must call this constructor when it is activated via the two parameter constructor described above. As a side-effect of construction, the remote object is "exported" to the RMI runtime (on the specified `port`) and is available to accept incoming calls from clients.

      Parameters:
        `id` - activation identifier for the object
        `port` - the port number on which the object is exported
        `csf` - the client-side socket factory for making calls to the remote object
        `ssf` - the server-side socket factory for receiving remote calls
      Throws:
        `RemoteException` - if exporting the object to the RMI runtime fails
        `UnsupportedOperationException` - if and only if activation is not supported by this implementation
      Since:
        1.2

  - ### Method Detail

    - #### getID

          protected ActivationID getID()

      Returns the object's activation identifier. The method is protected so that only subclasses can obtain an object's identifier.
      Returns:
        the object's activation identifier
      Since:
        1.2

    - #### register

          public static Remote register(ActivationDesc desc)
                                 throws UnknownGroupException,
                                        ActivationException,
                                        RemoteException

      Register an object descriptor for an activatable remote object so that is can be activated on demand.
      Parameters:
        `desc` - the object's descriptor
      Returns:
        the stub for the activatable remote object
      Throws:
        `UnknownGroupException` - if group id in `desc` is not registered with the activation system
        `ActivationException` - if activation system is not running
        `RemoteException` - if remote call fails
        `UnsupportedOperationException` - if and only if activation is not supported by this implementation
      Since:
        1.2

    - #### inactive

          public static boolean inactive(ActivationID id)
                                  throws UnknownObjectException,
                                         ActivationException,
                                         RemoteException

      Informs the system that the object with the corresponding activation `id` is currently inactive. If the object is currently active, the object is "unexported" from the RMI runtime (only if there are no pending or in-progress calls) so the that it can no longer receive incoming calls. This call informs this VM's ActivationGroup that the object is inactive, that, in turn, informs its ActivationMonitor. If this call completes successfully, a subsequent activate request to the activator will cause the object to reactivate. The operation may still succeed if the object is considered active but has already unexported itself.
      Parameters:
        `id` - the object's activation identifier
      Returns:
        true if the operation succeeds (the operation will succeed if the object in currently known to be active and is either already unexported or is currently exported and has no pending/executing calls); false is returned if the object has pending/executing calls in which case it cannot be deactivated
      Throws:
        `UnknownObjectException` - if object is not known (it may already be inactive)
        `ActivationException` - if group is not active
        `RemoteException` - if call informing monitor fails
        `UnsupportedOperationException` - if and only if activation is not supported by this implementation
      Since:
        1.2

    - #### unregister

          public static void unregister(ActivationID id)
                                 throws UnknownObjectException,
                                        ActivationException,
                                        RemoteException

      Revokes previous registration for the activation descriptor associated with `id`. An object can no longer be activated via that `id`.
      Parameters:
        `id` - the object's activation identifier
      Throws:
        `UnknownObjectException` - if object (`id`) is unknown
        `ActivationException` - if activation system is not running
        `RemoteException` - if remote call to activation system fails
        `UnsupportedOperationException` - if and only if activation is not supported by this implementation
      Since:
        1.2

    - #### exportObject

          public static ActivationID exportObject(Remote obj,
                                                  String location,
                                                  MarshalledObject<?> data,
                                                  boolean restart,
                                                  int port)
                                           throws ActivationException,
                                                  RemoteException

      Registers an activation descriptor (with the specified location, data, and restart mode) for the specified object, and exports that object with the specified port.

      Note: Using this method (as well as the `Activatable` constructors that both register and export an activatable remote object) is strongly discouraged because the actions of registering and exporting the remote object are not guaranteed to be atomic. Instead, an application should register an activation descriptor and export a remote object separately, so that exceptions can be handled properly.

      This method invokes the `exportObject` method with the specified object, location, data, restart mode, and port, and `null` for both client and server socket factories, and then returns the resulting activation identifier.

      Parameters:
        `obj` - the object being exported
        `location` - the object's code location
        `data` - the object's bootstrapping data
        `restart` - if true, the object is restarted (reactivated) when either the activator is restarted or the object's activation group is restarted after an unexpected crash; if false, the object is only activated on demand. Specifying `restart` to be `true` does not force an initial immediate activation of a newly registered object; initial activation is lazy.
        `port` - the port on which the object is exported (an anonymous port is used if port=0)
      Returns:
        the activation identifier obtained from registering the descriptor, `desc`, with the activation system the wrong group
      Throws:
        `ActivationException` - if activation group is not active
        `RemoteException` - if object registration or export fails
        `UnsupportedOperationException` - if and only if activation is not supported by this implementation
      Since:
        1.2

    - #### exportObject

          public static ActivationID exportObject(Remote obj,
                                                  String location,
                                                  MarshalledObject<?> data,
                                                  boolean restart,
                                                  int port,
                                                  RMIClientSocketFactory csf,
                                                  RMIServerSocketFactory ssf)
                                           throws ActivationException,
                                                  RemoteException

      Registers an activation descriptor (with the specified location, data, and restart mode) for the specified object, and exports that object with the specified port, and the specified client and server socket factories.

      Note: Using this method (as well as the `Activatable` constructors that both register and export an activatable remote object) is strongly discouraged because the actions of registering and exporting the remote object are not guaranteed to be atomic. Instead, an application should register an activation descriptor and export a remote object separately, so that exceptions can be handled properly.

      This method first registers an activation descriptor for the specified object as follows. It obtains the activation system by invoking the method `ActivationGroup.getSystem`. This method then obtains an `ActivationID` for the object by invoking the activation system's `registerObject` method with an `ActivationDesc` constructed with the specified object's class name, and the specified location, data, and restart mode. If an exception occurs obtaining the activation system or registering the activation descriptor, that exception is thrown to the caller.

      Next, this method exports the object by invoking the `exportObject` method with the specified remote object, the activation identifier obtained from registration, the specified port, and the specified client and server socket factories. If an exception occurs exporting the object, this method attempts to unregister the activation identifier (obtained from registration) by invoking the activation system's `unregisterObject` method with the activation identifier. If an exception occurs unregistering the identifier, that exception is ignored, and the original exception that occurred exporting the object is thrown to the caller.

      Finally, this method invokes the `activeObject` method on the activation group in this VM with the activation identifier and the specified remote object, and returns the activation identifier to the caller.

      Parameters:
        `obj` - the object being exported
        `location` - the object's code location
        `data` - the object's bootstrapping data
        `restart` - if true, the object is restarted (reactivated) when either the activator is restarted or the object's activation group is restarted after an unexpected crash; if false, the object is only activated on demand. Specifying `restart` to be `true` does not force an initial immediate activation of a newly registered object; initial activation is lazy.
        `port` - the port on which the object is exported (an anonymous port is used if port=0)
        `csf` - the client-side socket factory for making calls to the remote object
        `ssf` - the server-side socket factory for receiving remote calls
      Returns:
        the activation identifier obtained from registering the descriptor with the activation system
      Throws:
        `ActivationException` - if activation group is not active
        `RemoteException` - if object registration or export fails
        `UnsupportedOperationException` - if and only if activation is not supported by this implementation
      Since:
        1.2

    - #### exportObject

          public static Remote exportObject(Remote obj,
                                            ActivationID id,
                                            int port)
                                     throws RemoteException

      Export the activatable remote object to the RMI runtime to make the object available to receive incoming calls. The object is exported on an anonymous port, if `port` is zero.

      During activation, this `exportObject` method should be invoked explicitly by an "activatable" object, that does not extend the `Activatable` class. There is no need for objects that do extend the `Activatable` class to invoke this method directly because the object is exported during construction.

      Parameters:
        `obj` - the remote object implementation
        `id` - the object's activation identifier
        `port` - the port on which the object is exported (an anonymous port is used if port=0)
      Returns:
        the stub for the activatable remote object
      Throws:
        `RemoteException` - if object export fails
        `UnsupportedOperationException` - if and only if activation is not supported by this implementation
      Since:
        1.2

    - #### exportObject

          public static Remote exportObject(Remote obj,
                                            ActivationID id,
                                            int port,
                                            RMIClientSocketFactory csf,
                                            RMIServerSocketFactory ssf)
                                     throws RemoteException

      Export the activatable remote object to the RMI runtime to make the object available to receive incoming calls. The object is exported on an anonymous port, if `port` is zero.

      During activation, this `exportObject` method should be invoked explicitly by an "activatable" object, that does not extend the `Activatable` class. There is no need for objects that do extend the `Activatable` class to invoke this method directly because the object is exported during construction.

      Parameters:
        `obj` - the remote object implementation
        `id` - the object's activation identifier
        `port` - the port on which the object is exported (an anonymous port is used if port=0)
        `csf` - the client-side socket factory for making calls to the remote object
        `ssf` - the server-side socket factory for receiving remote calls
      Returns:
        the stub for the activatable remote object
      Throws:
        `RemoteException` - if object export fails
        `UnsupportedOperationException` - if and only if activation is not supported by this implementation
      Since:
        1.2

    - #### unexportObject

          public static boolean unexportObject(Remote obj,
                                               boolean force)
                                        throws NoSuchObjectException

      Remove the remote object, obj, from the RMI runtime. If successful, the object can no longer accept incoming RMI calls. If the force parameter is true, the object is forcibly unexported even if there are pending calls to the remote object or the remote object still has calls in progress. If the force parameter is false, the object is only unexported if there are no pending or in progress calls to the object.
      Parameters:
        `obj` - the remote object to be unexported
        `force` - if true, unexports the object even if there are pending or in-progress calls; if false, only unexports the object if there are no pending or in-progress calls
      Returns:
        true if operation is successful, false otherwise
      Throws:
        `NoSuchObjectException` - if the remote object is not currently exported
        `UnsupportedOperationException` - if and only if activation is not supported by this implementation
      Since:
        1.2

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