org.osgi.framework.hooks.resolver.ResolverHookFactory Maven / Gradle / Ivy
/*
* Copyright (c) OSGi Alliance (2011). 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.hooks.resolver;
import java.util.Collection;
import org.osgi.framework.Bundle;
import org.osgi.framework.wiring.BundleRevision;
import org.osgi.framework.wiring.FrameworkWiring;
/**
* OSGi Framework Resolver Hook Factory Service.
*
*
* Bundles registering this service will be called by the framework during
* a bundle resolver process to obtain a {@link ResolverHook resolver hook}
* instance which will be used for the duration of a resolve process.
*
* @ThreadSafe
* @see ResolverHook
* @version $Id: 4023566367435f07c047a7ba571f3bedc53aa37a $
*/
public interface ResolverHookFactory {
/**
* This method is called by the framework each time a resolve process begins
* to obtain a {@link ResolverHook resolver hook} instance. This resolver hook
* instance will be used for the duration of the resolve process. At the end of
* the resolve process the method {@link ResolverHook#end()} must be called by
* the framework and the framework must not hold any references of the resolver
* hook instance.
*
* The triggers represent the collection of bundles which triggered
* the resolve process. This collection may be empty if the triggers
* cannot be determined by the framework. In most cases the triggers
* can easily be determined. Calling certain methods on
* {@link Bundle bundle} when a bundle is in the {@link Bundle#INSTALLED INSTALLED}
* state will cause the framework to begin a resolve process in order to resolve the
* bundle. The following methods will start a resolve process in this case:
*
* - {@link Bundle#start() start}
* - {@link Bundle#loadClass(String) loadClass}
* - {@link Bundle#findEntries(String, String, boolean) findEntries}
* - {@link Bundle#getResource(String) getResource}
* - {@link Bundle#getResources(String) getResources}
*
* In such cases the collection will contain the single bundle which the
* framework is trying to resolve. Other cases will cause multiple bundles to be
* included in the trigger bundles collection. When {@link FrameworkWiring#resolveBundles(Collection)
* resolveBundles} is called the collection of triggers must include all the current bundle
* revisions for bundles passed to resolveBundles which are in the {@link Bundle#INSTALLED INSTALLED}
* state.
*
* When {@link FrameworkWiring#refreshBundles(Collection, org.osgi.framework.FrameworkListener...)}
* is called the collection of triggers is determined with the following steps:
*
* - If the collection of bundles passed is null then {@link FrameworkWiring#getRemovalPendingBundles()}
* is called to get the initial collection of bundles.
* - The equivalent of calling {@link FrameworkWiring#getDependencyClosure(Collection)} is called with
* the initial collection of bundles to get the dependency closure collection of the bundles being refreshed.
* - Remove any non-active bundles from the dependency closure collection.
* - For each bundle remaining in the dependency closure collection get the current bundle revision
* and add it to the collection of triggers.
*
*
* As described above, a resolve process is typically initiated as a result of calling API that causes the
* framework to attempt to resolve one or more bundles.
* The framework is free to start a resolve process at any time for reasons other than calls to framework API.
* For example, a resolve process may be used by the framework for diagnostic purposes and result in no
* bundles actually becoming resolved at the end of the process.
* Resolver hook implementations must be prepared for resolve processes that are initiated for other reasons
* besides calls to framework API.
* @param triggers an unmodifiable collection of bundles which triggered the resolve process.
* This collection may be empty if the collection of trigger bundles cannot be
* determined.
* @return a resolver hook instance to be used for the duration of the resolve process.
* A {@code null} value may be returned which indicates this resolver hook factory abstains from
* the resolve process.
*/
ResolverHook begin(Collection triggers);
}