/*
* Copyright 2015 Robert von Burg <eitch@eitchnet.ch>
*
* 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 li.strolch.policy;
import li.strolch.model.policy.PolicyDef;
import li.strolch.model.policy.PolicyDefVisitor;
import li.strolch.persistence.api.StrolchTransaction;
/**
* <p>
* The {@link PolicyHandler} is Strolch's mechanism of dependency injection
* </p>
*
* <p>
* Objects which require delegation can use a {@link PolicyConfiguration} element and then retrieve a StrolchPolicy
* instance from this {@link PolicyHandler}.
* </p>
*
* <p>
* {@link PolicyConfiguration} have a mapping of a policy type, i.e. an interface for a specific delegation. This
* interface has concrete implementations which are then returned by the {@link PolicyHandler} depending on the current
* configuration
* </p>
*
* <p>
* The resolving of a policy instance is handled by a {@link PolicyDefVisitor}
* <p>
*
* @author Robert von Burg <eitch@eitchnet.ch>
*/
public interface PolicyHandler {
/**
* Instantiates the actual policy by resolving the {@link PolicyDef} using a {@link PolicyDefVisitor}
*
* @param policyDef
* the {@link PolicyDef} referencing a concrete policy
* @param tx
* the current transaction for which the policy is instantiated
*
* @return the instantiated instance of the referenced policy
*/
public <T extends StrolchPolicy> T getPolicy(PolicyDef policyDef, StrolchTransaction tx);
}