Migratable (Java API Reference for Oracle WebLogic Server)

```
public interface Migratable
```
Every migratable service must implement the Migratable interface. This interface defines the methods that the migration framework will call to carry out migration. When a migratable service is deployed, an instance of the service class that implements this interface is installed on every potential host and registered with the local MigrationManager. The Migratable interface defines the methods used to manage the lifecycle of each instance.
When the instance is first deployed, the framework will call the migratableInitialize() method. When this method returns, the instance is initialized but inactive. Once an instance of the service has been deployed on each potential host, the framework chooses one instance to activate and calls the Migratable.migratableActivate() on that instance. When this call returns that instance of the service is active and all others are inactive. When it is time to migrate an instance, the framework first calls Migratable.migratableDeactivate() on the active instance. It then calls Migratable.migratableActivate() on the new instance. When the second call returns, migration is complete.
UNINITIALIZED | | initialize | deactivate V +------------->INACTIVE<----------+ | | | PREPARING_TO_DEACTIVATE | activate |deactivate ^ | | | V | +---------------ACTIVE------------+
An implementation must meet special requirements in order to function properly as a migratable service. Namely, it must guarantee that no service method called before the end of a lease will return after the lease has expired. This can be accomplished in one of two ways:
- Framework managed (default) - If the provider can declare a maximum method completion time, the framework will automatically disallow any call when the lease time remaining is less than this time. By default, the framework assumes a maximum completion time of 5 seconds for all methods. This time can be changed using the max-completion-time attribute in the RMI descriptor.
- Servce managed - If a service requires finer control, it can do its own lease checking. To use this, the provider must include the impl-managed-lease attribute in its RMI descriptor.

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`ACTIVATING`
`static int`	`ACTIVE`
`static int`	`DEFAULT_ORDER`
`static int`	`EARLY_ORDER`
`static int`	`FILESTORE_ORDER`
`static int`	`INACTIVE`
`static int`	`LATE_ORDER`
`static int`	`MDB_ORDER`

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`String`	`getName()`
`int`	`getOrder()` Returns the order value for this particular migratable object.
`void`	`migratableActivate()` Called to activate this instance of the migratable service.
`void`	`migratableDeactivate()` Called to deactivate this instance of the migratable service.
`void`	`migratableInitialize()` Called to initialize this instance of the migratable service.

- Field Detail
  - INACTIVE
```
static final int INACTIVE
```
    See Also:
    
    Constant Field Values
  - ACTIVE
```
static final int ACTIVE
```
    See Also:
    
    Constant Field Values
  - ACTIVATING
```
static final int ACTIVATING
```
    See Also:
    
    Constant Field Values
  - DEFAULT_ORDER
```
static final int DEFAULT_ORDER
```
    See Also:
    
    Constant Field Values
  - EARLY_ORDER
```
static final int EARLY_ORDER
```
    See Also:
    
    Constant Field Values
  - FILESTORE_ORDER
```
static final int FILESTORE_ORDER
```
    See Also:
    
    Constant Field Values
  - LATE_ORDER
```
static final int LATE_ORDER
```
    See Also:
    
    Constant Field Values
  - MDB_ORDER
```
static final int MDB_ORDER
```
    See Also:
    
    Constant Field Values
- Method Detail
  - getName
```
String getName()
```
  - migratableInitialize
```
void migratableInitialize()
                   throws MigrationException
```
    Called to initialize this instance of the migratable service. The cluster calls this method when this instance is registered with the local MigrationManagerService. When this call completes, the instance is considered initialized but inactive.
    
    Throws:
    
    MigrationException
  - migratableActivate
```
void migratableActivate()
                 throws MigrationException
```
    Called to activate this instance of the migratable service. The cluster ensures that only one instance is active at a time. This instance should respond by preparing to service requests. This will typically involve recovering the service state from persistent storage.
    
    Throws:
    
    MigrationException
  - migratableDeactivate
```
void migratableDeactivate()
                   throws MigrationException
```
    Called to deactivate this instance of the migratable service. This method is only called if the migration source server is healthy. In order to ensure that there is never more than one active instance, the cluster will call deactivate on the currently active instance before calling activate on another instance. The instance should release any claimed resources that may be required by the new instance. It may also take this opportunity to persist additional state to improve migration.
    A migratable can not depend on this method being called. It is only called in the case where the migration source is still healthy. For this reason, the migratable instance must be prepared for failure at all times. This method just provides this instance an opportunity to provide a more graceful migration when conditions permit.
    
    Throws:
    
    MigrationException
  - getOrder
```
int getOrder()
```
    Returns the order value for this particular migratable object. This controls in which order this object will be activated and deactivated with regards to all the other migratable objects deployed on a migratable target.

Interface Migratable

Field Summary

Method Summary

Field Detail

INACTIVE

ACTIVE

ACTIVATING

DEFAULT_ORDER

EARLY_ORDER

FILESTORE_ORDER

LATE_ORDER

MDB_ORDER

Method Detail

getName

migratableInitialize

migratableActivate

migratableDeactivate

getOrder