StreamingExtractor.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 gobblin.source.extractor;

import java.io.IOException;

import gobblin.annotation.Alpha;
import gobblin.writer.WatermarkStorage;


/**
 * An interface for implementing streaming / continuous extractors
 */
@Alpha
public interface StreamingExtractor<S, D> extends Extractor<S, RecordEnvelope<D>> {

  /**
   * Initialize the extractor to be ready to read records
   * @param watermarkStorage : watermark storage to retrieve previously committed watermarks
   * @throws IOException : typically if there was a failure in retrieving watermarks
   */
  void start(WatermarkStorage watermarkStorage) throws IOException;

}