/*
* Copyright (c) OSGi Alliance (2000, 2012). All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.osgi.framework;
import java.io.File;
import java.io.InputStream;
import java.util.Collection;
import java.util.Dictionary;
/**
* A bundle's execution context within the Framework. The context is used to
* grant access to other methods so that this bundle can interact with the
* Framework.
*
* <p>
* {@code BundleContext} methods allow a bundle to:
* <ul>
* <li>Subscribe to events published by the Framework.
* <li>Register service objects with the Framework service registry.
* <li>Retrieve {@code ServiceReferences} from the Framework service registry.
* <li>Get and release service objects for a referenced service.
* <li>Install new bundles in the Framework.
* <li>Get the list of bundles installed in the Framework.
* <li>Get the {@link Bundle} object for a bundle.
* <li>Create {@code File} objects for files in a persistent storage area
* provided for the bundle by the Framework.
* </ul>
*
* <p>
* A {@code BundleContext} object will be created for a bundle when the bundle
* is started. The {@code Bundle} object associated with a {@code BundleContext}
* object is called the <em>context bundle</em>.
*
* <p>
* The {@code BundleContext} object will be passed to the
* {@link BundleActivator#start(BundleContext)} method during activation of the
* context bundle. The same {@code BundleContext} object will be passed to the
* {@link BundleActivator#stop(BundleContext)} method when the context bundle is
* stopped. A {@code BundleContext} object is generally for the private use of
* its associated bundle and is not meant to be shared with other bundles in the
* OSGi environment.
*
* <p>
* The {@code BundleContext} object is only valid during the execution of its
* context bundle; that is, during the period from when the context bundle is in
* the {@code STARTING}, {@code STOPPING}, and {@code ACTIVE} bundle states. If
* the {@code BundleContext} object is used subsequently, an
* {@code IllegalStateException} must be thrown. The {@code BundleContext}
* object must never be reused after its context bundle is stopped.
*
* <p>
* Two {@code BundleContext} objects are equal if they both refer to the same
* execution context of a bundle. The Framework is the only entity that can
* create {@code BundleContext} objects and they are only valid within the
* Framework that created them.
*
* <p>
* A {@link Bundle} can be {@link Bundle#adapt(Class) adapted} to its
* {@code BundleContext}. In order for this to succeed, the caller must have the
* appropriate {@code AdminPermission[bundle,CONTEXT]} if the Java Runtime
* Environment supports permissions.
*
* @ThreadSafe
* @noimplement
* @version $Id: 4f166fd274f3965e48a7dbc239213d00e062b6d0 $
*/
public interface BundleContext extends BundleReference {
/**
* Returns the value of the specified property. If the key is not found in
* the Framework properties, the system properties are then searched. The
* method returns {@code null} if the property is not found.
*
* <p>
* All bundles must have permission to read properties whose names start
* with "org.osgi.".
*
* @param key The name of the requested property.
* @return The value of the requested property, or {@code null} if the
* property is undefined.
* @throws SecurityException If the caller does not have the appropriate
* {@code PropertyPermission} to read the property, and the Java
* Runtime Environment supports permissions.
*/
String getProperty(String key);
/**
* Returns the {@code Bundle} object associated with this
* {@code BundleContext}. This bundle is called the context bundle.
*
* @return The {@code Bundle} object associated with this
* {@code BundleContext}.
* @throws IllegalStateException If this BundleContext is no longer valid.
*/
Bundle getBundle();
/**
* Installs a bundle from the specified {@code InputStream} object.
*
* <p>
* If the specified {@code InputStream} is {@code null}, the Framework must
* create the {@code InputStream} from which to read the bundle by
* interpreting, in an implementation dependent manner, the specified
* {@code location}.
*
* <p>
* The specified {@code location} identifier will be used as the identity of
* the bundle. Every installed bundle is uniquely identified by its location
* identifier which is typically in the form of a URL.
*
* <p>
* The following steps are required to install a bundle:
* <ol>
* <li>If a bundle containing the same location identifier is already
* installed, the {@code Bundle} object for that bundle is returned.
*
* <li>The bundle's content is read from the input stream. If this fails, a
* {@link BundleException} is thrown.
*
* <li>The bundle's associated resources are allocated. The associated
* resources minimally consist of a unique identifier and a persistent
* storage area if the platform has file system support. If this step fails,
* a {@code BundleException} is thrown.
*
* <li>The bundle's state is set to {@code INSTALLED}.
*
* <li>A bundle event of type {@link BundleEvent#INSTALLED} is fired.
*
* <li>The {@code Bundle} object for the newly or previously installed
* bundle is returned.
* </ol>
*
* <b>Postconditions, no exceptions thrown </b>
* <ul>
* <li>{@code getState()} in { {@code INSTALLED}, {@code RESOLVED}
* }.
* <li>Bundle has a unique ID.
* </ul>
* <b>Postconditions, when an exception is thrown </b>
* <ul>
* <li>Bundle is not installed. If there was an existing bundle for the
* specified location, then that bundle must still be in the state it was
* prior to calling this method.</li>
* </ul>
*
* @param location The location identifier of the bundle to install.
* @param input The {@code InputStream} object from which this bundle will
* be read or {@code null} to indicate the Framework must create the
* input stream from the specified location identifier. The input
* stream must always be closed when this method completes, even if
* an exception is thrown.
* @return The {@code Bundle} object of the installed bundle.
* @throws BundleException If the installation failed. BundleException types
* thrown by this method include: {@link BundleException#READ_ERROR}
* , {@link BundleException#DUPLICATE_BUNDLE_ERROR},
* {@link BundleException#MANIFEST_ERROR}, and
* {@link BundleException#REJECTED_BY_HOOK}.
* @throws SecurityException If the caller does not have the appropriate
* {@code AdminPermission[installed bundle,LIFECYCLE]}, and the Java
* Runtime Environment supports permissions.
* @throws IllegalStateException If this BundleContext is no longer valid.
*/
Bundle installBundle(String location, InputStream input) throws BundleException;
/**
* Installs a bundle from the specified {@code location} identifier.
*
* <p>
* This method performs the same function as calling
* {@link #installBundle(String,InputStream)} with the specified
* {@code location} identifier and a {@code null} InputStream.
*
* @param location The location identifier of the bundle to install.
* @return The {@code Bundle} object of the installed bundle.
* @throws BundleException If the installation failed. BundleException types
* thrown by this method include: {@link BundleException#READ_ERROR}
* , {@link BundleException#DUPLICATE_BUNDLE_ERROR},
* {@link BundleException#MANIFEST_ERROR}, and
* {@link BundleException#REJECTED_BY_HOOK}.
* @throws SecurityException If the caller does not have the appropriate
* {@code AdminPermission[installed bundle,LIFECYCLE]}, and the Java
* Runtime Environment supports permissions.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @see #installBundle(String, InputStream)
*/
Bundle installBundle(String location) throws BundleException;
/**
* Returns the bundle with the specified identifier.
*
* @param id The identifier of the bundle to retrieve.
* @return A {@code Bundle} object or {@code null} if the identifier does
* not match any installed bundle.
*/
Bundle getBundle(long id);
/**
* Returns a list of all installed bundles.
* <p>
* This method returns a list of all bundles installed in the OSGi
* environment at the time of the call to this method. However, since the
* Framework is a very dynamic environment, bundles can be installed or
* uninstalled at anytime.
*
* @return An array of {@code Bundle} objects, one object per installed
* bundle.
*/
Bundle[] getBundles();
/**
* Adds the specified {@code ServiceListener} object with the specified
* {@code filter} to the context bundle's list of listeners. See
* {@link Filter} for a description of the filter syntax.
* {@code ServiceListener} objects are notified when a service has a
* lifecycle state change.
*
* <p>
* If the context bundle's list of listeners already contains a listener
* {@code l} such that {@code (l==listener)}, then this method replaces that
* listener's filter (which may be {@code null}) with the specified one
* (which may be {@code null}).
*
* <p>
* The listener is called if the filter criteria is met. To filter based
* upon the class of the service, the filter should reference the
* {@link Constants#OBJECTCLASS} property. If {@code filter} is {@code null}
* , all services are considered to match the filter.
*
* <p>
* When using a {@code filter}, it is possible that the {@code ServiceEvent}
* s for the complete lifecycle of a service will not be delivered to the
* listener. For example, if the {@code filter} only matches when the
* property {@code x} has the value {@code 1}, the listener will not be
* called if the service is registered with the property {@code x} not set
* to the value {@code 1}. Subsequently, when the service is modified
* setting property {@code x} to the value {@code 1}, the filter will match
* and the listener will be called with a {@code ServiceEvent} of type
* {@code MODIFIED}. Thus, the listener will not be called with a
* {@code ServiceEvent} of type {@code REGISTERED}.
*
* <p>
* If the Java Runtime Environment supports permissions, the
* {@code ServiceListener} object will be notified of a service event only
* if the bundle that is registering it has the {@code ServicePermission} to
* get the service using at least one of the named classes the service was
* registered under.
*
* @param listener The {@code ServiceListener} object to be added.
* @param filter The filter criteria.
* @throws InvalidSyntaxException If {@code filter} contains an invalid
* filter string that cannot be parsed.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @see ServiceEvent
* @see ServiceListener
* @see ServicePermission
*/
void addServiceListener(ServiceListener listener, String filter) throws InvalidSyntaxException;
/**
* Adds the specified {@code ServiceListener} object to the context bundle's
* list of listeners.
*
* <p>
* This method is the same as calling
* {@code BundleContext.addServiceListener(ServiceListener listener,
* String filter)} with {@code filter} set to {@code null}.
*
* @param listener The {@code ServiceListener} object to be added.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @see #addServiceListener(ServiceListener, String)
*/
void addServiceListener(ServiceListener listener);
/**
* Removes the specified {@code ServiceListener} object from the context
* bundle's list of listeners.
*
* <p>
* If {@code listener} is not contained in this context bundle's list of
* listeners, this method does nothing.
*
* @param listener The {@code ServiceListener} to be removed.
* @throws IllegalStateException If this BundleContext is no longer valid.
*/
void removeServiceListener(ServiceListener listener);
/**
* Adds the specified {@code BundleListener} object to the context bundle's
* list of listeners if not already present. BundleListener objects are
* notified when a bundle has a lifecycle state change.
*
* <p>
* If the context bundle's list of listeners already contains a listener
* {@code l} such that {@code (l==listener)}, this method does nothing.
*
* @param listener The {@code BundleListener} to be added.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @throws SecurityException If listener is a
* {@code SynchronousBundleListener} and the caller does not have
* the appropriate {@code AdminPermission[context bundle,LISTENER]},
* and the Java Runtime Environment supports permissions.
* @see BundleEvent
* @see BundleListener
*/
void addBundleListener(BundleListener listener);
/**
* Removes the specified {@code BundleListener} object from the context
* bundle's list of listeners.
*
* <p>
* If {@code listener} is not contained in the context bundle's list of
* listeners, this method does nothing.
*
* @param listener The {@code BundleListener} object to be removed.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @throws SecurityException If listener is a
* {@code SynchronousBundleListener} and the caller does not have
* the appropriate {@code AdminPermission[context bundle,LISTENER]},
* and the Java Runtime Environment supports permissions.
*/
void removeBundleListener(BundleListener listener);
/**
* Adds the specified {@code FrameworkListener} object to the context
* bundle's list of listeners if not already present. FrameworkListeners are
* notified of general Framework events.
*
* <p>
* If the context bundle's list of listeners already contains a listener
* {@code l} such that {@code (l==listener)}, this method does nothing.
*
* @param listener The {@code FrameworkListener} object to be added.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @see FrameworkEvent
* @see FrameworkListener
*/
void addFrameworkListener(FrameworkListener listener);
/**
* Removes the specified {@code FrameworkListener} object from the context
* bundle's list of listeners.
*
* <p>
* If {@code listener} is not contained in the context bundle's list of
* listeners, this method does nothing.
*
* @param listener The {@code FrameworkListener} object to be removed.
* @throws IllegalStateException If this BundleContext is no longer valid.
*/
void removeFrameworkListener(FrameworkListener listener);
/**
* Registers the specified service object with the specified properties
* under the specified class names into the Framework. A
* {@code ServiceRegistration} object is returned. The
* {@code ServiceRegistration} object is for the private use of the bundle
* registering the service and should not be shared with other bundles. The
* registering bundle is defined to be the context bundle. Other bundles can
* locate the service by using one of the
* {@link #getServiceReferences(Class, String)},
* {@link #getServiceReferences(String, String)},
* {@link #getServiceReference(Class)} or
* {@link #getServiceReference(String)} methods.
*
* <p>
* A bundle can register a service object that implements the
* {@link ServiceFactory} interface to have more flexibility in providing
* service objects to other bundles.
*
* <p>
* The following steps are required to register a service:
* <ol>
* <li>If {@code service} is not a {@code ServiceFactory}, an
* {@code IllegalArgumentException} is thrown if {@code service} is not an
* {@code instanceof} all the specified class names.
* <li>The Framework adds the following service properties to the service
* properties from the specified {@code Dictionary} (which may be
* {@code null}): <br/>
* A property named {@link Constants#SERVICE_ID} identifying the
* registration number of the service <br/>
* A property named {@link Constants#OBJECTCLASS} containing all the
* specified classes. <br/>
* Properties with these names in the specified {@code Dictionary} will be
* ignored.
* <li>The service is added to the Framework service registry and may now be
* used by other bundles.
* <li>A service event of type {@link ServiceEvent#REGISTERED} is fired.
* <li>A {@code ServiceRegistration} object for this registration is
* returned.
* </ol>
*
* @param clazzes The class names under which the service can be located.
* The class names in this array will be stored in the service's
* properties under the key {@link Constants#OBJECTCLASS}.
* @param service The service object or a {@code ServiceFactory} object.
* @param properties The properties for this service. The keys in the
* properties object must all be {@code String} objects. See
* {@link Constants} for a list of standard service property keys.
* Changes should not be made to this object after calling this
* method. To update the service's properties the
* {@link ServiceRegistration#setProperties(Dictionary)} method must
* be called. The set of properties may be {@code null} if the
* service has no properties.
* @return A {@code ServiceRegistration} object for use by the bundle
* registering the service to update the service's properties or to
* unregister the service.
* @throws IllegalArgumentException If one of the following is true:
* <ul>
* <li>{@code service} is {@code null}. <li>{@code service} is not a
* {@code ServiceFactory} object and is not an instance of all the
* named classes in {@code clazzes}. <li> {@code properties}
* contains case variants of the same key name.
* </ul>
* @throws SecurityException If the caller does not have the
* {@code ServicePermission} to register the service for all the
* named classes and the Java Runtime Environment supports
* permissions.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @see ServiceRegistration
* @see ServiceFactory
*/
ServiceRegistration<?> registerService(String[] clazzes, Object service, Dictionary<String, ?> properties);
/**
* Registers the specified service object with the specified properties
* under the specified class name with the Framework.
*
* <p>
* This method is otherwise identical to
* {@link #registerService(String[], Object, Dictionary)} and is provided as
* a convenience when {@code service} will only be registered under a single
* class name. Note that even in this case the value of the service's
* {@link Constants#OBJECTCLASS} property will be an array of string, rather
* than just a single string.
*
* @param clazz The class name under which the service can be located.
* @param service The service object or a {@code ServiceFactory} object.
* @param properties The properties for this service.
* @return A {@code ServiceRegistration} object for use by the bundle
* registering the service to update the service's properties or to
* unregister the service.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @see #registerService(String[], Object, Dictionary)
*/
ServiceRegistration<?> registerService(String clazz, Object service, Dictionary<String, ?> properties);
/**
* Registers the specified service object with the specified properties
* under the name of the specified class with the Framework.
*
* <p>
* This method is otherwise identical to
* {@link #registerService(String, Object, Dictionary)} and is provided to
* return a type safe {@code ServiceRegistration}.
*
* @param <S> Type of Service.
* @param clazz The class under whose name the service can be located.
* @param service The service object or a {@code ServiceFactory} object.
* @param properties The properties for this service.
* @return A {@code ServiceRegistration} object for use by the bundle
* registering the service to update the service's properties or to
* unregister the service.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @see #registerService(String, Object, Dictionary)
* @since 1.6
*/
<S> ServiceRegistration<S> registerService(Class<S> clazz, S service, Dictionary<String, ?> properties);
/**
* Returns an array of {@code ServiceReference} objects. The returned array
* of {@code ServiceReference} objects contains services that were
* registered under the specified class, match the specified filter
* expression, and the packages for the class names under which the services
* were registered match the context bundle's packages as defined in
* {@link ServiceReference#isAssignableTo(Bundle, String)}.
*
* <p>
* The list is valid at the time of the call to this method. However since
* the Framework is a very dynamic environment, services can be modified or
* unregistered at any time.
*
* <p>
* The specified {@code filter} expression is used to select the registered
* services whose service properties contain keys and values which satisfy
* the filter expression. See {@link Filter} for a description of the filter
* syntax. If the specified {@code filter} is {@code null}, all registered
* services are considered to match the filter. If the specified
* {@code filter} expression cannot be parsed, an
* {@link InvalidSyntaxException} will be thrown with a human readable
* message where the filter became unparsable.
*
* <p>
* The result is an array of {@code ServiceReference} objects for all
* services that meet all of the following conditions:
* <ul>
* <li>If the specified class name, {@code clazz}, is not {@code null}, the
* service must have been registered with the specified class name. The
* complete list of class names with which a service was registered is
* available from the service's {@link Constants#OBJECTCLASS objectClass}
* property.
* <li>If the specified {@code filter} is not {@code null}, the filter
* expression must match the service.
* <li>If the Java Runtime Environment supports permissions, the caller must
* have {@code ServicePermission} with the {@code GET} action for at least
* one of the class names under which the service was registered.
* <li>For each class name with which the service was registered, calling
* {@link ServiceReference#isAssignableTo(Bundle, String)} with the context
* bundle and the class name on the service's {@code ServiceReference}
* object must return {@code true}
* </ul>
*
* @param clazz The class name with which the service was registered or
* {@code null} for all services.
* @param filter The filter expression or {@code null} for all services.
* @return An array of {@code ServiceReference} objects or {@code null} if
* no services are registered which satisfy the search.
* @throws InvalidSyntaxException If the specified {@code filter} contains
* an invalid filter expression that cannot be parsed.
* @throws IllegalStateException If this BundleContext is no longer valid.
*/
ServiceReference<?>[] getServiceReferences(String clazz, String filter) throws InvalidSyntaxException;
/**
* Returns an array of {@code ServiceReference} objects. The returned array
* of {@code ServiceReference} objects contains services that were
* registered under the specified class and match the specified filter
* expression.
*
* <p>
* The list is valid at the time of the call to this method. However since
* the Framework is a very dynamic environment, services can be modified or
* unregistered at any time.
*
* <p>
* The specified {@code filter} expression is used to select the registered
* services whose service properties contain keys and values which satisfy
* the filter expression. See {@link Filter} for a description of the filter
* syntax. If the specified {@code filter} is {@code null}, all registered
* services are considered to match the filter. If the specified
* {@code filter} expression cannot be parsed, an
* {@link InvalidSyntaxException} will be thrown with a human readable
* message where the filter became unparsable.
*
* <p>
* The result is an array of {@code ServiceReference} objects for all
* services that meet all of the following conditions:
* <ul>
* <li>If the specified class name, {@code clazz}, is not {@code null}, the
* service must have been registered with the specified class name. The
* complete list of class names with which a service was registered is
* available from the service's {@link Constants#OBJECTCLASS objectClass}
* property.
* <li>If the specified {@code filter} is not {@code null}, the filter
* expression must match the service.
* <li>If the Java Runtime Environment supports permissions, the caller must
* have {@code ServicePermission} with the {@code GET} action for at least
* one of the class names under which the service was registered.
* </ul>
*
* @param clazz The class name with which the service was registered or
* {@code null} for all services.
* @param filter The filter expression or {@code null} for all services.
* @return An array of {@code ServiceReference} objects or {@code null} if
* no services are registered which satisfy the search.
* @throws InvalidSyntaxException If the specified {@code filter} contains
* an invalid filter expression that cannot be parsed.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @since 1.3
*/
ServiceReference<?>[] getAllServiceReferences(String clazz, String filter) throws InvalidSyntaxException;
/**
* Returns a {@code ServiceReference} object for a service that implements
* and was registered under the specified class.
*
* <p>
* The returned {@code ServiceReference} object is valid at the time of the
* call to this method. However as the Framework is a very dynamic
* environment, services can be modified or unregistered at any time.
*
* <p>
* This method is the same as calling
* {@link #getServiceReferences(String, String)} with a {@code null} filter
* expression and then finding the reference with the highest priority. It
* is provided as a convenience for when the caller is interested in any
* service that implements the specified class.
* <p>
* If multiple such services exist, the service with the highest priority is
* selected. This priority is defined as the service reference with the
* highest ranking (as specified in its {@link Constants#SERVICE_RANKING}
* property) is returned.
* <p>
* If there is a tie in ranking, the service with the lowest service ID (as
* specified in its {@link Constants#SERVICE_ID} property); that is, the
* service that was registered first is returned.
*
* @param clazz The class name with which the service was registered.
* @return A {@code ServiceReference} object, or {@code null} if no services
* are registered which implement the named class.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @see #getServiceReferences(String, String)
*/
ServiceReference<?> getServiceReference(String clazz);
/**
* Returns a {@code ServiceReference} object for a service that implements
* and was registered under the name of the specified class.
*
* <p>
* The returned {@code ServiceReference} object is valid at the time of the
* call to this method. However as the Framework is a very dynamic
* environment, services can be modified or unregistered at any time.
*
* <p>
* This method is the same as calling
* {@link #getServiceReferences(Class, String)} with a {@code null} filter
* expression. It is provided as a convenience for when the caller is
* interested in any service that implements the specified class.
* <p>
* If multiple such services exist, the service with the highest ranking (as
* specified in its {@link Constants#SERVICE_RANKING} property) is returned.
* <p>
* If there is a tie in ranking, the service with the lowest service ID (as
* specified in its {@link Constants#SERVICE_ID} property); that is, the
* service that was registered first is returned.
*
* @param <S> Type of Service.
* @param clazz The class under whose name the service was registered. Must
* not be {@code null}.
* @return A {@code ServiceReference} object, or {@code null} if no services
* are registered which implement the specified class.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @see #getServiceReferences(Class, String)
* @since 1.6
*/
<S> ServiceReference<S> getServiceReference(Class<S> clazz);
/**
* Returns a collection of {@code ServiceReference} objects. The returned
* collection of {@code ServiceReference} objects contains services that
* were registered under the name of the specified class, match the
* specified filter expression, and the packages for the class names under
* which the services were registered match the context bundle's packages as
* defined in {@link ServiceReference#isAssignableTo(Bundle, String)}.
*
* <p>
* The collection is valid at the time of the call to this method. However
* since the Framework is a very dynamic environment, services can be
* modified or unregistered at any time.
*
* <p>
* The specified {@code filter} expression is used to select the registered
* services whose service properties contain keys and values which satisfy
* the filter expression. See {@link Filter} for a description of the filter
* syntax. If the specified {@code filter} is {@code null}, all registered
* services are considered to match the filter. If the specified
* {@code filter} expression cannot be parsed, an
* {@link InvalidSyntaxException} will be thrown with a human readable
* message where the filter became unparsable.
*
* <p>
* The result is a collection of {@code ServiceReference} objects for all
* services that meet all of the following conditions:
* <ul>
* <li>The service must have been registered with the name of the specified
* class. The complete list of class names with which a service was
* registered is available from the service's {@link Constants#OBJECTCLASS
* objectClass} property.
* <li>If the specified {@code filter} is not {@code null}, the filter
* expression must match the service.
* <li>If the Java Runtime Environment supports permissions, the caller must
* have {@code ServicePermission} with the {@code GET} action for at least
* one of the class names under which the service was registered.
* <li>For each class name with which the service was registered, calling
* {@link ServiceReference#isAssignableTo(Bundle, String)} with the context
* bundle and the class name on the service's {@code ServiceReference}
* object must return {@code true}
* </ul>
*
* @param <S> Type of Service
* @param clazz The class under whose name the service was registered. Must
* not be {@code null}.
* @param filter The filter expression or {@code null} for all services.
* @return A collection of {@code ServiceReference} objects. May be empty if
* no services are registered which satisfy the search.
* @throws InvalidSyntaxException If the specified {@code filter} contains
* an invalid filter expression that cannot be parsed.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @since 1.6
*/
<S> Collection<ServiceReference<S>> getServiceReferences(Class<S> clazz, String filter) throws InvalidSyntaxException;
/**
* Returns the service object referenced by the specified
* {@code ServiceReference} object.
* <p>
* A bundle's use of a service is tracked by the bundle's use count of that
* service. Each time a service's service object is returned by
* {@link #getService(ServiceReference)} the context bundle's use count for
* that service is incremented by one. Each time the service is released by
* {@link #ungetService(ServiceReference)} the context bundle's use count
* for that service is decremented by one.
* <p>
* When a bundle's use count for a service drops to zero, the bundle should
* no longer use that service.
*
* <p>
* This method will always return {@code null} when the service associated
* with this {@code reference} has been unregistered.
*
* <p>
* The following steps are required to get the service object:
* <ol>
* <li>If the service has been unregistered, {@code null} is returned.
* <li>If the context bundle's use count for the service is currently zero
* and the service was registered with an object implementing the
* {@code ServiceFactory} interface, the
* {@link ServiceFactory#getService(Bundle, ServiceRegistration)} method is
* called to create a service object for the context bundle. If the service
* object returned by the {@code ServiceFactory} object is {@code null}, not
* an {@code instanceof} all the classes named when the service was
* registered or the {@code ServiceFactory} object throws an exception or
* will be recursively called for the context bundle, {@code null} is
* returned and a Framework event of type {@link FrameworkEvent#ERROR}
* containing a {@link ServiceException} describing the error is fired. <br>
* This service object is cached by the Framework. While the context
* bundle's use count for the service is greater than zero, subsequent calls
* to get the services's service object for the context bundle will return
* the cached service object.
* <li>The context bundle's use count for this service is incremented by
* one.
* <li>The service object for the service is returned.
* </ol>
*
* @param <S> Type of Service.
* @param reference A reference to the service.
* @return A service object for the service associated with
* {@code reference} or {@code null} if the service is not
* registered, the service object returned by a
* {@code ServiceFactory} does not implement the classes under which
* it was registered or the {@code ServiceFactory} threw an
* exception.
* @throws SecurityException If the caller does not have the
* {@code ServicePermission} to get the service using at least one
* of the named classes the service was registered under and the
* Java Runtime Environment supports permissions.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @throws IllegalArgumentException If the specified
* {@code ServiceReference} was not created by the same framework
* instance as this {@code BundleContext}.
* @see #ungetService(ServiceReference)
* @see ServiceFactory
*/
<S> S getService(ServiceReference<S> reference);
/**
* Releases the service object referenced by the specified
* {@code ServiceReference} object. If the context bundle's use count for
* the service is zero, this method returns {@code false}. Otherwise, the
* context bundle's use count for the service is decremented by one.
*
* <p>
* The service's service object should no longer be used and all references
* to it should be destroyed when a bundle's use count for the service drops
* to zero.
*
* <p>
* The following steps are required to unget the service object:
* <ol>
* <li>If the context bundle's use count for the service is zero or the
* service has been unregistered, {@code false} is returned.
* <li>The context bundle's use count for this service is decremented by
* one.
* <li>If the context bundle's use count for the service is currently zero
* and the service was registered with a {@code ServiceFactory} object, the
* {@link ServiceFactory#ungetService(Bundle, ServiceRegistration, Object)}
* method is called to release the service object for the context bundle.
* <li>{@code true} is returned.
* </ol>
*
* @param reference A reference to the service to be released.
* @return {@code false} if the context bundle's use count for the service
* is zero or if the service has been unregistered; {@code true}
* otherwise.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @throws IllegalArgumentException If the specified
* {@code ServiceReference} was not created by the same framework
* instance as this {@code BundleContext}.
* @see #getService(ServiceReference)
* @see ServiceFactory
*/
boolean ungetService(ServiceReference<?> reference);
/**
* Creates a {@code File} object for a file in the persistent storage area
* provided for the bundle by the Framework. This method will return
* {@code null} if the platform does not have file system support.
*
* <p>
* A {@code File} object for the base directory of the persistent storage
* area provided for the context bundle by the Framework can be obtained by
* calling this method with an empty string as {@code filename}.
*
* <p>
* If the Java Runtime Environment supports permissions, the Framework will
* ensure that the bundle has the {@code java.io.FilePermission} with
* actions {@code read},{@code write},{@code delete} for all files
* (recursively) in the persistent storage area provided for the context
* bundle.
*
* @param filename A relative name to the file to be accessed.
* @return A {@code File} object that represents the requested file or
* {@code null} if the platform does not have file system support.
* @throws IllegalStateException If this BundleContext is no longer valid.
*/
File getDataFile(String filename);
/**
* Creates a {@code Filter} object. This {@code Filter} object may be used
* to match a {@code ServiceReference} object or a {@code Dictionary}
* object.
*
* <p>
* If the filter cannot be parsed, an {@link InvalidSyntaxException} will be
* thrown with a human readable message where the filter became unparsable.
*
* @param filter The filter string.
* @return A {@code Filter} object encapsulating the filter string.
* @throws InvalidSyntaxException If {@code filter} contains an invalid
* filter string that cannot be parsed.
* @throws NullPointerException If {@code filter} is null.
* @throws IllegalStateException If this BundleContext is no longer valid.
* @see "Framework specification for a description of the filter string syntax."
* @see FrameworkUtil#createFilter(String)
* @since 1.1
*/
Filter createFilter(String filter) throws InvalidSyntaxException;
/**
* Returns the bundle with the specified location.
*
* @param location The location of the bundle to retrieve.
* @return A {@code Bundle} object or {@code null} if the location does not
* match any installed bundle.
* @since 1.6
*/
Bundle getBundle(String location);
}