org.fourthline.cling.model

## Class DefaultServiceManager<T>

- java.lang.Object
- - org.fourthline.cling.model.DefaultServiceManager<T>

- All Implemented Interfaces:
    ServiceManager<T>

      public class DefaultServiceManager<T>
      extends Object
      implements ServiceManager<T>

  Default implementation, creates and manages a single instance of a plain Java bean.

  Creates instance of the defined service class when it is first needed (acts as a factory), manages the instance in a field (it's shared), and synchronizes (locks) all multi-threaded access. A locking attempt will timeout after 500 milliseconds with a runtime exception if another operation is already in progress. Override `getLockTimeoutMillis()` to customize this behavior, e.g. if your service bean is slow and requires more time for typical action executions or state variable reading.

  Author:
    Christian Bauer

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `protected class` | `DefaultServiceManager.DefaultPropertyChangeListener`

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected ReentrantLock` | `lock`
    `protected PropertyChangeSupport` | `propertyChangeSupport`
    `protected LocalService<T>` | `service`
    `protected Class<T>` | `serviceClass`
    `protected T` | `serviceImpl`

    - ### Fields inherited from interface org.fourthline.cling.model.ServiceManager

      `EVENTED_STATE_VARIABLES`

  - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `DefaultServiceManager(LocalService<T> service)`
    `` | `DefaultServiceManager(LocalService<T> service, Class<T> serviceClass)`

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected PropertyChangeListener` | `createPropertyChangeListener(T serviceImpl)`
    `protected PropertyChangeSupport` | `createPropertyChangeSupport(T serviceImpl)`
    `protected T` | `createServiceInstance()`
    `void` | `execute(Command<T> cmd)` Double-dispatch of arbitrary commands, used by action executors and state variable accessors.
    `Collection<StateVariableValue>` | `getCurrentState()` Reading the state of a service manually.
    `protected Collection<StateVariableValue>` | `getCurrentState(String[] variableNames)`
    `T` | `getImplementation()`
    `protected int` | `getLockTimeoutMillis()`
    `PropertyChangeSupport` | `getPropertyChangeSupport()` Provides the capability to monitor the service for state changes.
    `LocalService<T>` | `getService()`
    `protected void` | `init()`
    `protected void` | `lock()`
    `protected Collection<StateVariableValue>` | `readInitialEventedStateVariableValues()`
    `String` | `toString()`
    `protected void` | `unlock()`

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

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

- - ### Field Detail

    - #### service

          protected final LocalService<T> service

    - #### serviceClass

          protected final Class<T> serviceClass

    - #### lock

          protected final ReentrantLock lock

    - #### serviceImpl

          protected T serviceImpl

    - #### propertyChangeSupport

          protected PropertyChangeSupport propertyChangeSupport

  - ### Constructor Detail

    - #### DefaultServiceManager

          protected DefaultServiceManager(LocalService<T> service)

    - #### DefaultServiceManager

          public DefaultServiceManager(LocalService<T> service,
                               Class<T> serviceClass)

  - ### Method Detail

    - #### lock

          protected void lock()

    - #### unlock

          protected void unlock()

    - #### getLockTimeoutMillis

          protected int getLockTimeoutMillis()

    - #### getService

          public LocalService<T> getService()

      Specified by:
        `getService` in interface `ServiceManager<T>`
      Returns:
        The metadata of the service to which this manager is assigned.

    - #### getImplementation

          public T getImplementation()

      Specified by:
        `getImplementation` in interface `ServiceManager<T>`
      Returns:
        An instance with the interface expected by the bound `ActionExecutor`s and `StateVariableAccessor`s.

    - #### getPropertyChangeSupport

          public PropertyChangeSupport getPropertyChangeSupport()

      Description copied from interface: `ServiceManager`
      Provides the capability to monitor the service for state changes.

      The GENA subsystem expects that this adapter will notify its listeners whenever any evented UPnP state variable of the service has changed its state. The following change event is expected:

      - The property name is the constant `ServiceManager.EVENTED_STATE_VARIABLES`.
      - The "old value" can be `null`, only the current state has to be included.
      - The "new value" is a `Collection` of `StateVariableValue`, representing the current state of the service after the change.

      The collection has to include values for all state variables, no matter what state variable was updated. Any other event is ignored (e.g. individual property changes).

      Specified by:
        `getPropertyChangeSupport` in interface `ServiceManager<T>`
      Returns:
        An adapter that will notify its listeners whenever any evented state variable changes.

    - #### execute

          public void execute(Command<T> cmd)
                       throws Exception

      Description copied from interface: `ServiceManager`
      Double-dispatch of arbitrary commands, used by action executors and state variable accessors.

      The service manager will execute the given `Command` and it might decorate the execution, for example, by locking/unlocking access to a shared service implementation before and after the execution.

      Specified by:
        `execute` in interface `ServiceManager<T>`
      Parameters:
        `cmd` - The command to execute.
      Throws:
        `Exception` - Any exception, without wrapping, as thrown by `Command.execute(ServiceManager)`

    - #### getCurrentState

          public Collection<StateVariableValue> getCurrentState()
                                                         throws Exception

      Description copied from interface: `ServiceManager`
      Reading the state of a service manually.
      Specified by:
        `getCurrentState` in interface `ServiceManager<T>`
      Returns:
        A `Collection` of `StateVariableValue`, representing the current state of the service, that is, all evented state variable values.
      Throws:
        `Exception` - Any error that occurred when the service's state was accessed.

    - #### getCurrentState

          protected Collection<StateVariableValue> getCurrentState(String[] variableNames)
                                                            throws Exception

      Throws:
        `Exception`

    - #### init

          protected void init()

    - #### createServiceInstance

          protected T createServiceInstance()
                                     throws Exception

      Throws:
        `Exception`

    - #### createPropertyChangeSupport

          protected PropertyChangeSupport createPropertyChangeSupport(T serviceImpl)
                                                               throws Exception

      Throws:
        `Exception`

    - #### createPropertyChangeListener

          protected PropertyChangeListener createPropertyChangeListener(T serviceImpl)
                                                                 throws Exception

      Throws:
        `Exception`

    - #### readInitialEventedStateVariableValues

          protected Collection<StateVariableValue> readInitialEventedStateVariableValues()
                                                                                  throws Exception

      Throws:
        `Exception`

    - #### toString

          public String toString()

      Overrides:
        `toString` in class `Object`

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