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/*
 * Copyright 2017 StreamSets 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.streamsets.pipeline.api;

/**
 * 
 * Typifies error codes with built-in localization support. Pipeline exceptions use error codes.
 * 
 * Error code implementations are typically enums, i.e.:
 *
 *  *
 * public enum BaseError implements ErrorCode {
 *   API_00("Stage '{}', there should be 1 output lane but there are '{}'");
 *
 *   private final String msg;
 *
 *   BaseError(String msg) {
 *     this.msg = msg;
 *   }
 *
 *   public String getCode() {
 *     return name();
 *   }
 *
 *   public String getMessage() {
 *     return msg;
 *   }
 *
 * }
 * 
 *
 * 
 * Built in localization looks for a Properties based ResourceBundle matching the
 * ErrorCode implementation. The ErrorCode's code is used as the key within the
 * ResourceBundle. If the bundle is not available, or the key is not defined within the bundle, the
 * ErrorCode's message will be used.
 * 
 * Typically, the message can be a template, using {} as positional placeholders for values.
 * {@link com.streamsets.pipeline.api.StageException} take an ErrorCode plus variable arguments on its
 * constructors and generates the exception message using the ErrorCode message as template then variable
 * argument as the values for it.
 */
public interface ErrorCode {

  /**
   * Returns the error code.
   *
   * @return the error code.
   */
  public String getCode();

  /**
   * Returns the built-in default message for the error code.
   *
   * @return the default message template
   */
  public String getMessage();

}