javax.tv.service.selection
Interface ServiceContext
- public interface ServiceContext
A ServiceContext
represents an environment in which
services are presented in a broadcast receiver. Applications may
use ServiceContext
objects to select new services to
be presented. Content associated with a selected service is
presented by one or more ServiceContentHandler
objects
managed by the ServiceContext
.
A ServiceContext
can exist in four states -
presenting, not presenting, presentation
pending and destroyed. The initial state is
not presenting.
The select()
method can be called from any state
except destroyed. Assuming no exception is thrown, the
service context then enters the presentation pending
state. No event is generated on this state transition. If a call to
select()
completes successfully, either a
NormalContentEvent
or an
AlternativeContentEvent
is generated and the
ServiceContext
moves into the presenting
state.
If the selection operation fails, a
SelectionFailedEvent
is generated. If the
select()
method is called during the presentation
pending state, a SelectionFailedEvent
with reason
code INTERRUPTED
is generated, and the
ServiceContext
will proceed in the presentation
pending state for the most recent select() call.
Otherwise, if the state before the failed select operation was
not presenting, the ServiceContext
will
return to that state and a PresentationTerminatedEvent
be generated. If the state before the failed select operation was
presenting, it will attempt to return to that previous
state, which can result in a NormalContentEvent
or
AlternativeContentEvent
if this is possible, or a
PresentationTerminatedEvent
if it is not possible.
The not presenting state is entered due to service
presentation being stopped which is reported by a
PresentationTerminatedEvent
. The stopping of service
presentation can be initiated by an application calling the
stop()
method or because some change in the environment
makes continued presentation impossible.
The destroyed state is entered by calling the
destroy()
method, and is signaled by a
ServiceContextDestroyedEvent
. Once this state is
entered, the ServiceContext
can no longer be used for
any purpose. A destroyed ServiceContext
will be
eligible for garbage collection once all references to it by any
applications have been removed.
Note that the ability to select a service for presentation does not
imply exclusive rights to the resources required for that
presentation. Subsequent attempts to select the same service may
fail.
Applications may also use this interface to register for events
associated with ServiceContext
state changes.
- See Also:
Service
,
ServiceContentHandler
,
NormalContentEvent
,
AlternativeContentEvent
,
SelectionFailedEvent
,
PresentationTerminatedEvent
,
ServiceContextDestroyedEvent
,
ServiceContextListener
Method Summary |
void |
addListener(ServiceContextListener listener)
Subscribes a listener to receive events related to this
ServiceContext . |
void |
destroy()
Causes the ServiceContext to release all resources
and enter the destroyed state. |
Service |
getService()
Reports the Service being presented in this
ServiceContext . |
ServiceContentHandler[] |
getServiceContentHandlers()
Reports the current collection of ServiceContentHandlers. |
void |
removeListener(ServiceContextListener listener)
Unsubscribes a listener from receiving events related to this
ServiceContext . |
void |
select(Locator[] components)
Selects content by specifying the parts of a service to be
presented. |
void |
select(Service selection)
Selects a service to be presented in this
ServiceContext . |
void |
stop()
Causes the ServiceContext to stop presenting content
and enter the not presenting state. |
select
public void select(Service selection)
throws java.lang.SecurityException
- Selects a service to be presented in this
ServiceContext
. If the ServiceContext
is already presenting content, the new selection replaces the
content being presented. If the ServiceContext
is
not presenting, successful conclusion of this operation results in
the ServiceContext
entering the presenting
state.
This method is asynchronous and successful completion of the
selection is notified by either a NormalContentEvent
or a AlternativeContentEvent
. If an exception is
thrown when this method is called, the state of the service
context does not change. In such a case, any service being
presented before this method was called will continue to be
presented.
If the selection process fails after this method returns, a
SelectionFailedEvent
will be generated. In this
case, the system will attempt to return to presenting the
original service (if any). If this is not possible (due, for
example, to issues such as tuning or CA) the
ServiceContext
will enter the not
presenting state and a
PresentationTerminatedEvent
will be generated.
If the ServiceContext
is currently presenting a
service and components of the current service are also to be
presented in the newly selected service, these components will
continue to be presented and will not be restarted. If the
calling application is not a part of the newly selected service
and the application lifecycle policy on the receiver dictates
that the calling application be terminated, termination of the
application will be affected through the application lifecycle
API.
If the provided Service
is transport-independent,
this method will resolve the Service
to a
transport-dependent Service
before performing the
selection. The actual Service
selected will be
reported through the getService()
method.
Successful completion of a select operation using this method
provides ServiceContentHandler
instances for all
components that are signaled as "auto-start" in the selected
service. Upon entering the presenting state, these
ServiceContentHandler
instances will have begun
presenting their respective content;
ServiceMediaHandler
instances will be in the
started state.
- Parameters:
selection
- The Service
the service to be
selected.- Throws:
java.lang.SecurityException
- If the caller owns this
ServiceContext
but does not have
SelectPermission(selection.getLocator(), "own")
, or if
the caller
does not own this ServiceContext
and does not have
SelectPermission(selection.getLocator(), "*")
.java.lang.IllegalStateException
- If the ServiceContext
has been destroyed.- See Also:
NormalContentEvent
,
AlternativeContentEvent
,
SelectionFailedEvent
,
PresentationTerminatedEvent
,
Service
,
getService()
,
ServiceContentHandler
,
destroy()
select
public void select(Locator[] components)
throws InvalidLocatorException,
InvalidServiceComponentException,
java.lang.SecurityException
- Selects content by specifying the parts of a service to be
presented. If the
ServiceContext
is
already presenting content, the new selection replaces the
content being presented. If the
ServiceContext
is not presenting,
successful conclusion of this operation results in the
ServiceContext
entering the
presenting state.
This method is asynchronous and successful completion of the
selection is notified by either a single
NormalContentEvent
or a single
AlternativeContentEvent
. If failure of the
selection can be determined when this method is called, an
exception will be generated and the state of the
ServiceContext
will not change. In this case, any
service being presented before this method was called will
continue to be presented.
If failure of the selection is determined after this method
returns, a SelectionFailedEvent
will be
generated. In this case, the implementation of the method will
try to return to presenting the original service (if any). If
this is not possible (due, for example, to issues such as tuning
or CA) the ServiceContext
will enter the
not presenting state and a
PresentationTerminatedEvent
will be generated.
If the ServiceContext
is currently presenting a service and
components of the current service are also to be presented in the
newly selected content, these components will continue to be
presented and will not be restarted. If the calling application
is not a part of the newly selected content and the application
lifecycle policy on the receiver dictates that the calling
application be terminated, termination of the application
will be affected through the application lifecycle API.
Successful completion of a select operation using this method
provides ServiceContentHandler
instances for all
components that are indicated in the components
parameter. Upon entering the presenting state, these
ServiceContentHandler
instances will have begun
presenting their respective content;
ServiceMediaHandler
instances will be in the
started state. This method will not provide
ServiceContentHandler
instances for service
components for which a locator is not specified.
- Parameters:
components
- An array of Locator
instances
representing the parts of this service to be selected. Each
array element must be a locator to either a
ServiceComponent
or content within a service
component (such as an Xlet).- Throws:
InvalidLocatorException
- If a Locator
provided
does not reference a selectable service component or selectable
content within a service component.InvalidServiceComponentException
- If a
specified service component must be presented in conjunction
with another service component not contained in
components
, if the specified
components are not all members of the same service, or if the
specified set of components cannot be presented as a coherent
whole.java.lang.SecurityException
- If, for any valid i
, the
caller owns this ServiceContext
but does not have
SelectPermission(components[i], "own")
, or if the caller
does not own this ServiceContext
and does not have
SelectPermission(components[i], "*")
.java.lang.IllegalStateException
- If the ServiceContext
has been destroyed.- See Also:
NormalContentEvent
,
AlternativeContentEvent
,
SelectionFailedEvent
,
PresentationTerminatedEvent
,
ServiceContentHandler
,
ServiceComponent
stop
public void stop()
throws java.lang.SecurityException
- Causes the
ServiceContext
to stop presenting content
and enter the not presenting state. Resources used
in the presentation will be released, associated
ServiceContentHandlers
will cease presentation
(ServiceMediaHandlers
will no longer be in the
started state), and a
PresentationTerminatedEvent
will be posted.
This operation completes asynchronously. No action is performed
if the ServiceContext
is already in the not
presenting state.
- Throws:
java.lang.SecurityException
- If the caller owns this
ServiceContext
but does not have
ServiceContextPermission("stop", "own")
, or if the caller
does not own this ServiceContext
and does not have
SelectPermission("stop", "*")
.java.lang.IllegalStateException
- If the ServiceContext
has been destroyed.
destroy
public void destroy()
throws java.lang.SecurityException
- Causes the
ServiceContext
to release all resources
and enter the destroyed state. This method indicates
that the the ServiceContext
must cease further
activity, and that it will no longer be used. After completion
of this method, ServiceMediaHandler
instances
associated with this ServiceContext
will have become
unrealized or will have been closed.
If the ServiceContext
is currently in the
presenting or presentation pending state, this
method will first stop the ServiceContext
, causing a
PresentationTerminatedEvent
to be posted. After the
ServiceContext
has moved to the destroyed
state, a ServiceContextDestroyedEvent
will be
posted.
This operation completes asynchronously. No action is performed
if the ServiceContext
is already in the
destroyed state.
- Throws:
java.lang.SecurityException
- If the caller does not have permission
to call stop()
on this ServiceContext
,
or if the caller owns this ServiceContext
but does
not have ServiceContextPermission("destroy", "own")
,
or if the caller does not own this ServiceContext
and does not have SelectPermission("destroy", "*")
.- See Also:
stop()
getServiceContentHandlers
public ServiceContentHandler[] getServiceContentHandlers()
throws java.lang.SecurityException
- Reports the current collection of ServiceContentHandlers. A
zero-length array is returned if the
ServiceContext
is in the not presenting or presentation
pending states.
- Returns:
- The current
ServiceContentHandler
instances. - Throws:
java.lang.SecurityException
- If the caller owns this
ServiceContext
but does not have
ServiceContextPermission("getServiceContentHandlers",
"own")
, or if the caller does not own this
ServiceContext
and does not have
SelectPermission("getServiceContentHandlers", "*")
.java.lang.IllegalStateException
- If the ServiceContext
has been destroyed.
getService
public Service getService()
- Reports the
Service
being presented in this
ServiceContext
. If the ServiceContext
is currently presenting a service, the Service
returned will be a network-dependent representation of the
Service
indicated in the last successful
select()
method call. If the
ServiceContext
is not in the presenting
state then null
is returned.
- Returns:
- The service currently being presented.
- Throws:
java.lang.IllegalStateException
- If the ServiceContext
has been destroyed.
addListener
public void addListener(ServiceContextListener listener)
- Subscribes a listener to receive events related to this
ServiceContext
. If the specified listener is currently
subscribed, no action is performed.
- Parameters:
listener
- The ServiceContextListener
to subscribe.- Throws:
java.lang.IllegalStateException
- If the ServiceContext
has been
destroyed.- See Also:
ServiceContextEvent
removeListener
public void removeListener(ServiceContextListener listener)
- Unsubscribes a listener from receiving events related to this
ServiceContext
. If the specified listener is not currently
subscribed, no action is performed.
- Parameters:
listener
- The ServiceContextListener
to unsubscribe.- Throws:
java.lang.IllegalStateException
- If the ServiceContext
has been
destroyed.
Copyright © 1998 - 2000 Sun Microsystems, Inc.