RecordWrapperSchemaGenerator.java

/*
 * Copyright 2014-2016 CyberVision, 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 org.kaaproject.kaa.server.common.log.shared;

import org.apache.avro.Schema;
import org.kaaproject.kaa.server.common.log.shared.avro.gen.RecordHeader;
import org.kaaproject.kaa.server.common.utils.FileUtils;

import java.io.IOException;

public class RecordWrapperSchemaGenerator {

  /**
   * The Constant RECORD_WRAPPER_SCHEMA_TEMPLATE.
   */
  private static final String
          RECORD_WRAPPER_SCHEMA_TEMPLATE = "avro/record_wrapper_schema.avsc.template";
  /**
   * The Constant RECORD_HEADER_SCHEMA_VAR.
   */
  private static final String RECORD_HEADER_SCHEMA_VAR = "\\$\\{record_header_schema\\}";
  /**
   * The Constant RECORD_DATA_SCHEMA_VAR.
   */
  private static final String RECORD_DATA_SCHEMA_VAR = "\\$\\{record_data_schema\\}";
  public static String RECORD_HEADER_FIELD = "recordHeader";
  public static String RECORD_DATA_FIELD = "recordData";
  private static String recordWrapperSchemaTemplate;

  private RecordWrapperSchemaGenerator() {
  }

  /**
   * Generate record wrapper schema.
   *
   * @param userRecordSchema is user record schema which we wrapped by record wrapper schema
   * @return record wrapper schema
   * @throws IOException Signals that an I/O exception has occurred
   */
  public static Schema generateRecordWrapperSchema(String userRecordSchema) throws IOException {
    if (recordWrapperSchemaTemplate == null) {
      recordWrapperSchemaTemplate = FileUtils.readResource(RECORD_WRAPPER_SCHEMA_TEMPLATE);
      String recordHeaderSchema = RecordHeader.getClassSchema().toString();
      recordWrapperSchemaTemplate =
              recordWrapperSchemaTemplate.replaceAll(RECORD_HEADER_SCHEMA_VAR, recordHeaderSchema);
    }
    String recordWrapperSchemaString =
            recordWrapperSchemaTemplate.replaceAll(RECORD_DATA_SCHEMA_VAR, userRecordSchema);
    Schema.Parser parser = new Schema.Parser();
    Schema recordWrapperSchema = parser.parse(recordWrapperSchemaString);
    return recordWrapperSchema;
  }

}