001/*
002 * Copyright (c) 2007-2015 Concurrent, Inc. All Rights Reserved.
003 *
004 * Project and contact information: http://www.cascading.org/
005 *
006 * This file is part of the Cascading project.
007 *
008 * Licensed under the Apache License, Version 2.0 (the "License");
009 * you may not use this file except in compliance with the License.
010 * You may obtain a copy of the License at
011 *
012 *     http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing, software
015 * distributed under the License is distributed on an "AS IS" BASIS,
016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017 * See the License for the specific language governing permissions and
018 * limitations under the License.
019 */
020
021package cascading.flow;
022
023import java.io.Serializable;
024import java.util.Set;
025
026import cascading.flow.planner.Scope;
027import cascading.property.ConfigDef;
028import cascading.tuple.Fields;
029
030/**
031 * Interface FlowElement is a utility interface used internally to simplify DAG management. It is not intended
032 * for users to interact with these methods directly.
033 */
034public interface FlowElement extends Serializable
035  {
036  /**
037   * Method outgoingScopeFor returns the Scope this FlowElement hands off to the next FlowElement.
038   *
039   * @param incomingScopes of type Set<Scope>
040   * @return Scope
041   */
042  Scope outgoingScopeFor( Set<Scope> incomingScopes );
043
044  /**
045   * Method resolveIncomingOperationArgumentFields returns the Fields outgoing from the previous FlowElement that
046   * are consumable by this FlowElement when preparing Operation arguments.
047   *
048   * @param incomingScope of type Scope
049   * @return Fields
050   */
051  Fields resolveIncomingOperationArgumentFields( Scope incomingScope );
052
053  /**
054   * Method resolveIncomingOperationPassThroughFields returns the Fields outgoing from the previous FlowElement that
055   * are consumable by this FlowElement when preparing the Pipe outgoing tuple.
056   *
057   * @param incomingScope of type Scope
058   * @return Fields
059   */
060  Fields resolveIncomingOperationPassThroughFields( Scope incomingScope );
061
062  boolean isEquivalentTo( FlowElement element );
063
064  ConfigDef getConfigDef();
065
066  boolean hasConfigDef();
067
068  ConfigDef getNodeConfigDef();
069
070  boolean hasNodeConfigDef();
071
072  ConfigDef getStepConfigDef();
073
074  boolean hasStepConfigDef();
075  }