java.beans.beancontext

Interface BeanContextServices

public interface BeanContextServices extends BeanContext, BeanContextServicesListener

Allows a BeanContext to provide services to its children.

Since: 1.2

UNKNOWN: it is unclear whether a BeanContextServices should delegate unhandled requests to parents. I assume so.

Method Summary
voidaddBeanContextServicesListener(BeanContextServicesListener listener)
Add a listener on all adds and removes of services.
booleanaddService(Class serviceClass, BeanContextServiceProvider provider)
Register a service to make it available to others.
IteratorgetCurrentServiceClasses()
Get a list of all service classes supported.
IteratorgetCurrentServiceSelectors(Class serviceClass)
Get a list of valid service selectors for the specified service class.
ObjectgetService(BeanContextChild requestorChild, Object requestor, Class serviceClass, Object serviceSelector, BeanContextServiceRevokedListener listener)
Get a service from this BeanContextServices.
booleanhasService(Class serviceClass)
Tell whether the specified service class is available.
voidreleaseService(BeanContextChild requestorChild, Object requestor, Object service)
Release your copy of this service.
voidremoveBeanContextServicesListener(BeanContextServicesListener listener)
Remove a listener on all adds and removes of services.
voidrevokeService(Class serviceClass, BeanContextServiceProvider provider, boolean revokeNow)
Make it so that no one else can use this service.

Method Detail

addBeanContextServicesListener

public void addBeanContextServicesListener(BeanContextServicesListener listener)
Add a listener on all adds and removes of services.

Parameters: listener the listener to add.

addService

public boolean addService(Class serviceClass, BeanContextServiceProvider provider)
Register a service to make it available to others. This class may refuse to add the service based on whatever information it can gather, including whether the service provider is trusted.

Parameters: serviceClass the service class. provider the factory that will actually provide the service.

Returns: whether the service was added or not.

getCurrentServiceClasses

public Iterator getCurrentServiceClasses()
Get a list of all service classes supported.

This method must synchronize on BeanContext.globalHierarchyLock.

Returns: a list of all service classes supported.

See Also: globalHierarchyLock

getCurrentServiceSelectors

public Iterator getCurrentServiceSelectors(Class serviceClass)
Get a list of valid service selectors for the specified service class.

If the specified service class does not have a finite number of valid service selectors, it should return null. If it takes a general Integer parameter, for example, you may as well return null or the poor soul who called this method will be iterating all day.

If it has no valid service selectors, it should still return an empty Iterator.

Parameters: serviceClass the service class to get selectors for.

Returns: a list of valid service selectors for the service class, or null.

getService

public Object getService(BeanContextChild requestorChild, Object requestor, Class serviceClass, Object serviceSelector, BeanContextServiceRevokedListener listener)
Get a service from this BeanContextServices.

The specified listener will be registered to receive a revocation notice for the specified serviceClass. One notification per service class per requestor object will be sent.

The listener will be unregistered when all services that were obtained by that requestor for that service class are released.

If the requested service class is not available, or if this BeanContextServices object chooses not honor the request because the service class has been revoked or for some other reason, then this method will return null.

This method may throw unchecked exceptions, so watch out.

Parameters: requestorChild the BeanContextChild associated with the requestor. Typically this will be the same as the requestor itself, but since any Object, even one outside the hierarchy, may make a request, this parameter is necessary. Only weak references to this will be retained, and it will never be changed, only queried in a read-only manner. requestor the actual requestor of the service. Only weak references to this will be retained, and it will never be changed, only queried in a read-only manner. serviceClass the Class of the service being requested. serviceSelector a parameter to customize the service returned with. listener a listener that will be notified if the service being requested is revoked.

Returns: an instance of serviceClass (such that instanceof serviceClass is true), or null.

UNKNOWN: it is not specified what happens when two subsequent calls are made to getService() with the same requestor object and service class but different listeners. Which listener is to be notified?

hasService

public boolean hasService(Class serviceClass)
Tell whether the specified service class is available. Iff getService() could return a non-null value for the specified service, this method will return true.

Parameters: serviceClass the service class to check on.

Returns: whether the specified service class is available.

releaseService

public void releaseService(BeanContextChild requestorChild, Object requestor, Object service)
Release your copy of this service.

If all copies of the service's class have been relinquished by the requestor, the BeanContextServiceRevokedListener previously registered by getService() will be unregistered.

Parameters: requestorChild the original BeanContextChild requesting the service. requestor the original requestor of the service. service the service to relinquish

See Also: getService

removeBeanContextServicesListener

public void removeBeanContextServicesListener(BeanContextServicesListener listener)
Remove a listener on all adds and removes of services.

Parameters: listener the listener to add.

UNKNOWN: it is not certain whether this should remove this listener if it was specified in getService().

revokeService

public void revokeService(Class serviceClass, BeanContextServiceProvider provider, boolean revokeNow)
Make it so that no one else can use this service.

If revokeNow is false, the only effect of this method is to make all subsequent calls to getService() on this service class fail.

If it is true, a message is also sent out to all listeners on the service and all references to it are released.

Parameters: serviceClass the service class to revoke. provider the service provider providing the service class. revokeNow whether to release all current references to the service.