001/* 002 * Copyright (c) 2007-2017 Xplenty, 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.tap; 022 023import java.io.IOException; 024 025import cascading.flow.FlowProcess; 026import cascading.scheme.Scheme; 027import cascading.tuple.Fields; 028import cascading.tuple.TupleEntryIterator; 029 030/** 031 * Class SinkTap is an optional base class for sink only Taps. 032 * <p/> 033 * Some {@link cascading.tap.Tap} instances may only be sinks (as opposed 034 * to being a source). These types may subclass SinkTap for convenience or 035 * set {@link #isSource()} to {@code false} in a custom Tap sub-class. 036 */ 037public abstract class SinkTap<Config, Output> extends Tap<Config, Void, Output> 038 { 039 protected SinkTap() 040 { 041 } 042 043 protected SinkTap( Scheme<Config, ?, Output, ?, ?> scheme ) 044 { 045 super( (Scheme<Config, Void, Output, ?, ?>) scheme ); 046 } 047 048 protected SinkTap( Scheme<Config, ?, Output, ?, ?> scheme, SinkMode sinkMode ) 049 { 050 super( (Scheme<Config, Void, Output, ?, ?>) scheme, sinkMode ); 051 } 052 053 @Override 054 public Fields getSourceFields() 055 { 056 throw new UnsupportedOperationException( "unable to source tuple streams via a SinkTap instance" ); 057 } 058 059 @Override 060 public boolean prepareResourceForRead( Config conf ) throws IOException 061 { 062 throw new UnsupportedOperationException( "unable to prepare resource for read via a SinkTap instance" ); 063 } 064 065 @Override 066 public boolean isSource() 067 { 068 return false; 069 } 070 071 @Override 072 public void sourceConfInit( FlowProcess<? extends Config> flowProcess, Config conf ) 073 { 074 throw new UnsupportedOperationException( "unable to source tuple streams via a SinkTap instance" ); 075 } 076 077 @Override 078 public TupleEntryIterator openForRead( FlowProcess<? extends Config> flowProcess, Void input ) throws IOException 079 { 080 throw new UnsupportedOperationException( "unable to open for read via a SinkTap instance" ); 081 } 082 }