Previewer.java

/**
 * Copyright 2015 StreamSets Inc.
 *
 * Licensed under 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 com.streamsets.datacollector.execution;

import com.streamsets.datacollector.runner.PipelineRuntimeException;
import com.streamsets.datacollector.runner.StageOutput;
import com.streamsets.datacollector.store.PipelineStoreException;
import com.streamsets.datacollector.util.PipelineException;

import javax.ws.rs.core.MultivaluedMap;

import java.util.List;

public interface Previewer {

  // a Previewer lives for duration of a preview pipeline operation (validateConfig or start)

  // we should have a implementation that has a synchronous start() (by the time it finishes the status is final)

  // we should have a proxy implementation that uses the synchronous one and calls start() within a separate thread
  // making it the start() asynchronous. The manager should cache this one.

  // Implementations receive a PreviewerListener at <init> time, the listener is owned by the Manager

  public String getId();

  public String getName();

  public String getRev();

  public void validateConfigs(long timeoutMillis) throws PipelineException;

  public RawPreview getRawSource(int maxLength, MultivaluedMap<String, String> previewParams)
      throws PipelineException;

  public void start(int batches, int batchSize, boolean skipTargets, String stopStage, List<StageOutput> stagesOverride,
                    long timeoutMillis) throws PipelineException;

  public void stop();

  // in the case of the synchronous one the only acceptable value is -1 (wait until it finishes)
  // in the case of the asynchronous one acceptable values are 0 (dispatch and wait) and greater (dispatch and block for millis)
  public boolean waitForCompletion(long timeoutMillis) throws PipelineException;

  public PreviewStatus getStatus();

  public PreviewOutput getOutput();

}