| /** |
| * Copyright (C) 2015 DataTorrent, Inc. |
| * |
| * 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 com.datatorrent.api; |
| |
| /** |
| * Input operators ie operators which do not consume payload from other operators but are able |
| * to generate the payload for other operators must implement this interface. |
| * |
| * It's an error to provide input ports on operators which implement this interface since existence |
| * of ports contradicts with the purpose of the interface. |
| * |
| * @since 0.3.2 |
| */ |
| public interface InputOperator extends Operator |
| { |
| /** |
| * The input operators are given an opportunity to emit the tuples which will be marked |
| * as belonging to the windowId identified by immediately preceding beginWindow call. |
| * |
| * emitTuples can implement one or more tuples. Ideally it should emit as many tuples as |
| * possible without going over the streaming window width boundary. Since operators can |
| * easily spend too much time making that check, when not convenient they should emit |
| * only as many tuples as they can confidently within the current window. The streaming |
| * engine will make sure to call emitTuples multiple times within a giving streaming |
| * window if it can. When it cannot, it will call endWindow. |
| */ |
| public void emitTuples(); |
| |
| } |