samoa-flink/src/main/java/org/apache/samoa/flink/topology/impl/FlinkComponent.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.samoa.flink.topology.impl;

import org.apache.flink.streaming.api.datastream.DataStream;

/**
 * Common interface of FlinkEntranceProcessingItem and FlinkProcessingItem
 */
public interface FlinkComponent {

	/**
	 * An initiation of the node. It should create the right invokables and apply the appropriate
	 * stream transformations
	 */
	public void initialise();

	/**
	 * This check is needed in order to determine whether all requirements for a Flink Component 
	 * (DataStream) are satisfied in order to initialise it. This is necessary in this integration
	 * since Flink Streaming applies eager datastream generation based on transformations.
	 * 
	 * @return 
	 */
	public boolean canBeInitialised();

	/**
	 * 
	 * @return
	 */
	public boolean isInitialised();

	/**
	 * The wrapped Flink DataStream generated by this Flink component. Mind that the component 
	 * should first be initialised in order to have a generated DataStream
	 * 
	 * @return
	 */
	public DataStream<SamoaType> getOutStream();

	/**
	 * A unique component id
	 * 
	 * @return
	 */
	public int getComponentId();

}