001 /* 002 * Copyright (c) 2007-2014 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 */ 020 021 package cascading.flow; 022 023 import java.util.List; 024 import java.util.Map; 025 026 import cascading.pipe.Pipe; 027 028 /** 029 * Interface AssemblyPlanner is used to allow for lazy evaluation of a pipe assembly during planning of a {@link Flow}. 030 * <p/> 031 * This allows for new languages or frameworks that may require additional meta-data from the 032 * underlying platform or environment. Specifically field names and type information from incoming source 033 * and outgoing sink {@link cascading.tap.Tap}s. 034 * <p/> 035 * AssemblyPlanner implementations are handed to a {@link cascading.flow.planner.FlowPlanner} 036 * instance in the order they should be evaluated. 037 * Every instance has the opportunity to replace any prior tails with new branches and paths. 038 * <p/> 039 * Every instance of AssemblyPlanner evaluated is given the current {@link FlowDef} used on the current 040 * {@link FlowConnector}, the current Flow instance (only initialized with source and sink Taps provided by the 041 * FlowDef), and the tails provided by the FlowDef or those returned by prior AssemblyPlanner instances. 042 * <p/> 043 * An AssemblyPlanner cannot change or modify the Flow, or change out any Taps used as sources, sinks, traps, or 044 * checkpoints. 045 * <p/> 046 * This is an experimental API and subject to change without notice. 047 */ 048 public interface AssemblyPlanner 049 { 050 interface Context 051 { 052 FlowDef getFlowDef(); 053 054 Flow getFlow(); 055 056 List<Pipe> getTails(); 057 } 058 059 /** 060 * Called when this AssemblyPlanner instance should return any additional tail Pipe instances for used 061 * when completing the Flow plan. 062 * 063 * @param context parameter object of the Context 064 * @return tail Pipe instances to replace the given tails 065 */ 066 List<Pipe> resolveTails( Context context ); 067 068 /** 069 * Returns a map of properties giving more details about the Flow object. This can be picked up by a Flow object and 070 * added to its internal FlowDescriptor. 071 * 072 * @return Map<String,String> 073 */ 074 Map<String, String> getFlowDescriptor(); 075 }