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/*
 * Copyright (c) OSGi Alliance (2006, 2017). 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.
 */

// This document is an experimental draft to enable interoperability
// between bundle repositories. There is currently no commitment to
// turn this draft into an official specification.

package org.osgi.service.resolver;

import java.util.List;
import java.util.Map;

import org.osgi.annotation.versioning.ProviderType;
import org.osgi.framework.namespace.PackageNamespace;
import org.osgi.resource.Namespace;
import org.osgi.resource.Requirement;
import org.osgi.resource.Resource;
import org.osgi.resource.Wire;
import org.osgi.resource.Wiring;


A resolver service resolves the specified resources in the context supplied
by the caller.

Author:$Id: 86bff007315e1e3c03eca6aaacdcfa379be9ddea $
@ThreadSafe
/**
 * A resolver service resolves the specified resources in the context supplied
 * by the caller.
 * 
 * @ThreadSafe
 * @author $Id: 86bff007315e1e3c03eca6aaacdcfa379be9ddea $
 */
@ProviderType
public interface Resolver {
	
Resolve the specified resolve context and return any new resources and
wires to the caller.


The resolver considers two groups of resources:

    

  • Mandatory - any resource in the mandatory group must be resolved. A failure to satisfy any mandatory requirement for these resources will result in throwing a ResolutionException
    • 

  • Optional - any resource in the optional group may be resolved. A failure to satisfy a mandatory requirement for a resource in this group will not fail the overall resolution but no resources or wires will be returned for that resource.
    • 



 The resolve method returns the delta between the start state defined by ResolveContext.getWirings() and the end resolved state. That is, only new resources and wires are included. 

The behavior of the resolver is not defined if the specified resolve
context supplies inconsistent information.

Params:
  • context – The resolve context for the resolve operation. Must not be null.
Throws:
Returns:The new resources and wires required to satisfy the specified
        resolve context. The returned map is the property of the caller
        and can be modified by the caller.
/**
	 * Resolve the specified resolve context and return any new resources and
	 * wires to the caller.
	 * 
	 * <p>
	 * The resolver considers two groups of resources:
	 * <ul>
	 * <li>Mandatory - any resource in the
	 * {@link ResolveContext#getMandatoryResources() mandatory group} must be
	 * resolved. A failure to satisfy any mandatory requirement for these
	 * resources will result in throwing a {@link ResolutionException}</li>
	 * <li>Optional - any resource in the
	 * {@link ResolveContext#getOptionalResources() optional group} may be
	 * resolved. A failure to satisfy a mandatory requirement for a resource in
	 * this group will not fail the overall resolution but no resources or wires
	 * will be returned for that resource.</li>
	 * </ul>
	 * 
	 * <p>
	 * The resolve method returns the delta between the start state defined by
	 * {@link ResolveContext#getWirings()} and the end resolved state. That is,
	 * only new resources and wires are included.
	 * 
	 * <p>
	 * The behavior of the resolver is not defined if the specified resolve
	 * context supplies inconsistent information.
	 * 
	 * @param context The resolve context for the resolve operation. Must not be
	 *        {@code null}.
	 * @return The new resources and wires required to satisfy the specified
	 *         resolve context. The returned map is the property of the caller
	 *         and can be modified by the caller.
	 * @throws ResolutionException If the resolution cannot be satisfied.
	 */
	Map<Resource, List<Wire>> resolve(ResolveContext context) throws ResolutionException;

	
Resolves a given requirement dynamically for the given host wiring using
the given resolve context and return any new resources and wires to the
caller.

 The requirement must be a 
requirement of the wiring and must use the package namespace with a resolution of type dynamic. 
 The resolve context is not asked for mandatory resources or for optional resources. The resolve context is asked to find providers for the given requirement. The matching 
package capabilities returned by the resolve context must not have a osgi.wiring.package attribute equal to a package capability already wired to by the wiring or equal a package capability provided by the wiring. The resolve context may be requested to find providers for other requirements in order to resolve the resources that provide the matching capabilities to the given requirement. 
 If the requirement 
cardinality is not multiple then no new wire must be created if the wires of the wiring already contain a wire that uses the 
requirement 
 This operation may resolve additional resources in order to resolve the dynamic requirement. The returned map will contain entries for each resource that got resolved in addition to the specified wiring resource. The wire list for the wiring resource will only contain one wire which is for the dynamic requirement. 
Params:
  • context – The resolve context for the resolve operation. Must not be null.
  • hostWiring – The wiring with the dynamic requirement. Must not be null.
  • dynamicRequirement – The dynamic requirement. Must not be null.
Throws:
Returns:The new resources and wires required to satisfy the specified
        dynamic requirement. The returned map is the property of the
        caller and can be modified by the caller. If no new wires were
        created then a ResolutionException is thrown.
/**
	 * Resolves a given requirement dynamically for the given host wiring using
	 * the given resolve context and return any new resources and wires to the
	 * caller.
	 * <p>
	 * The requirement must be a {@link Wiring#getResourceRequirements(String)
	 * requirement} of the wiring and must use the
	 * {@link PackageNamespace#PACKAGE_NAMESPACE package} namespace with a
	 * {@link Namespace#REQUIREMENT_RESOLUTION_DIRECTIVE resolution} of type
	 * {@link PackageNamespace#RESOLUTION_DYNAMIC dynamic}.
	 * <p>
	 * The resolve context is not asked for
	 * {@link ResolveContext#getMandatoryResources() mandatory} resources or for
	 * {@link ResolveContext#getMandatoryResources() optional} resources. The
	 * resolve context is asked to
	 * {@link ResolveContext#findProviders(Requirement) find providers} for the
	 * given requirement. The matching {@link PackageNamespace#PACKAGE_NAMESPACE
	 * package} capabilities returned by the resolve context must not have a
	 * {@link PackageNamespace#PACKAGE_NAMESPACE osgi.wiring.package} attribute
	 * equal to a {@link PackageNamespace#PACKAGE_NAMESPACE package} capability
	 * already {@link Wiring#getRequiredResourceWires(String) wired to} by the
	 * wiring or equal a {@link PackageNamespace#PACKAGE_NAMESPACE package}
	 * capability {@link Wiring#getResourceCapabilities(String) provided} by the
	 * wiring. The resolve context may be requested to
	 * {@link ResolveContext#findProviders(Requirement) find providers} for
	 * other requirements in order to resolve the resources that provide the
	 * matching capabilities to the given requirement.
	 * <p>
	 * If the requirement {@link Namespace#REQUIREMENT_CARDINALITY_DIRECTIVE
	 * cardinality} is not {@link Namespace#CARDINALITY_MULTIPLE multiple} then
	 * no new wire must be created if the
	 * {@link Wiring#getRequiredResourceWires(String) wires} of the wiring
	 * already contain a wire that uses the {@link Wire#getRequirement()
	 * requirement}
	 * <p>
	 * This operation may resolve additional resources in order to resolve the
	 * dynamic requirement. The returned map will contain entries for each
	 * resource that got resolved in addition to the specified wiring
	 * {@link Wiring#getResource() resource}. The wire list for the wiring
	 * resource will only contain one wire which is for the dynamic requirement.
	 * 
	 * @param context The resolve context for the resolve operation. Must not be
	 *            {@code null}.
	 * @param hostWiring The wiring with the dynamic
	 *            {@link Wiring#getResourceRequirements(String) requirement}.
	 *            Must not be {@code null}.
	 * @param dynamicRequirement The dynamic requirement. Must not be
	 *            {@code null}.
	 * @return The new resources and wires required to satisfy the specified
	 *         dynamic requirement. The returned map is the property of the
	 *         caller and can be modified by the caller. If no new wires were
	 *         created then a ResolutionException is thrown.
	 * @throws ResolutionException if the dynamic requirement cannot be resolved
	 */
	public Map<Resource,List<Wire>> resolveDynamic(ResolveContext context,
			Wiring hostWiring, Requirement dynamicRequirement)
			throws ResolutionException;
}