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/*-
* ============LICENSE_START=======================================================
* Copyright (C) 2016-2018 Ericsson. All rights reserved.
* Modifications Copyright (C) 2019 Nordix Foundation.
* ================================================================================
* 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.
*
* SPDX-License-Identifier: Apache-2.0
* ============LICENSE_END=========================================================
*/
package org.onap.policy.apex.core.engine.executor;
import java.util.Properties;
import org.onap.policy.apex.core.engine.ExecutorParameters;
import org.onap.policy.apex.core.engine.executor.exception.StateMachineException;
import org.onap.policy.apex.model.basicmodel.concepts.ApexException;
import org.onap.policy.apex.model.basicmodel.concepts.AxConcept;
/**
* This interface defines what operations must be provided by an executing entity in Apex. It is
* implemented by classes that execute logic in a state machine. Each executor has an incoming
* entity {@code IN} that triggers execution, an outgoing entity {@code OUT} that is produced by
* execution, a subject {@code SUBJECT} that is being executed, and a context {@code CONTEXT} in
* which execution is being carried out. An executor can be part of a chain of executors and the
* {@code setNext} method is used to set the next executor to be executed after this executor has
* completed.
*
* @author Sven van der Meer (sven.van.der.meer@ericsson.com)
* @author Liam Fallon (liam.fallon@ericsson.com)
*
* @param <I> type of the incoming entity
* @param <O> type of the outgoing entity
* @param <S> type that is the subject of execution
* @param <C> context holding the context of execution
*/
public interface Executor<I, O, S, C> {
/**
* Save the subject and context of the executor.
*
* @param parent the parent executor of this executor or null if this executor is the top
* executor
* @param executorSubject the executor subject, the subject of execution
* @param executorContext the executor context, the context in which execution takes place
*/
void setContext(Executor<?, ?, ?, ?> parent, S executorSubject, C executorContext);
/**
* Prepares the processing.
*
* @throws StateMachineException thrown when a state machine execution error occurs
*/
void prepare() throws StateMachineException;
/**
* Executes the executor, running through its context in its natural order.
*
* @param executionId the execution ID of the current APEX execution policy thread
* @param executionProperties the execution properties to set
* @param incomingEntity the incoming entity that triggers execution
* @return The outgoing entity that is the result of execution
* @throws ApexException on an execution error
*/
O execute(long executionId, Properties executionProperties, I incomingEntity) throws ApexException;
/**
* Carry out the preparatory work for execution.
*
* @param executionId the execution ID of the current APEX execution policy thread
* @param executionProperties the execution properties to set
* @param incomingEntity the incoming entity that triggers execution
* @throws ApexException on an execution error
*/
void executePre(long executionId, Properties executionProperties, I incomingEntity) throws ApexException;
/**
* Carry out the post work for execution, the returning entity should be set by the child
* execution object.
*
* @param returnValue the return value indicates whether the execution was successful and, if it
* failed, how it failed
* @throws ApexException on an execution error
*/
void executePost(boolean returnValue) throws ApexException;
/**
* Cleans up after processing.
*
* @throws StateMachineException thrown when a state machine execution error occurs
*/
void cleanUp() throws StateMachineException;
/**
* Get the key associated with the executor.
*
* @return The key associated with the executor
*/
AxConcept getKey();
/**
* Get the parent executor of the executor.
*
* @return The parent executor of this executor
*/
@SuppressWarnings("rawtypes")
Executor getParent();
/**
* Get the subject of the executor.
*
* @return The subject for the executor
*/
S getSubject();
/**
* Get the context of the executor.
*
* @return The context for the executor
*/
C getContext();
/**
* Get the incoming object of the executor.
*
* @return The incoming object for the executor
*/
I getIncoming();
/**
* Get the outgoing object of the executor.
*
* @return The outgoing object for the executor
*/
O getOutgoing();
/**
* Save the next executor for this executor.
*
* @param nextExecutor the next executor
*/
void setNext(Executor<I, O, S, C> nextExecutor);
/**
* Get the next executor to be run after this executor completes its execution.
*
* @return The next executor
*/
Executor<I, O, S, C> getNext();
/**
* Set parameters for this executor, overloaded by executors that use parameters.
*
* @param parameters executor parameters
*/
void setParameters(ExecutorParameters parameters);
}
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