text: /*
   * Copyright 2017 dmb.star-net.cn
   *
   * 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.
   */
  
  'use strict';
  
  var PayloadPacket = {
  
      appendPayload : function (header, payload) {
          if (payload === null) {
             header.writeInt(-1);
             return header;
          } else {
              header.writeInt(payload.length);
              return Buffer.concat([header.getBuffer(), payload]);
          }
      },
  
      readPayload : function (buffer) {
          var len = buffer.readInt();    
          if(len <= 0){
              return new Buffer();
          }
          return buffer.readBytes(len);
      }
  
  };
  
  
  module.exports = PayloadPacket;
  