content: /* Copyright 2010, Object Management Group, Inc.
   * Copyright 2010, PrismTech, Inc.
   * Copyright 2010, Real-Time Innovations, Inc.
   * All rights reserved.
   *
   * 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.omg.dds.core.policy;
  
  /**
   * User data not known by the middleware, but distributed by means of
   * built-in topics. The default value is an empty (zero-sized) sequence.
   *<p>
   * <b>Concerns:</b> {@link org.omg.dds.domain.DomainParticipant}, {@link org.omg.dds.sub.DataReader},
   *                 {@link org.omg.dds.pub.DataWriter}
   *<p>
   * <b>RxO:</b> No
   *<p>
   * <b>Changeable:</b> Yes
   *<p>
   * The purpose of this QoS is to allow the application to attach additional
   * information to the created {@link org.omg.dds.core.Entity} objects such that when a remote
   * application discovers their existence it can access that information and
   * use it for its own purposes. One possible use of this QoS is to attach
   * security credentials or some other information that can be used by the
   * remote application to authenticate the source. In combination with
   * operations such as
   * {@link org.omg.dds.domain.DomainParticipant#ignoreParticipant(org.omg.dds.core.InstanceHandle)},
   * {@link org.omg.dds.domain.DomainParticipant#ignorePublication(org.omg.dds.core.InstanceHandle)},
   * {@link org.omg.dds.domain.DomainParticipant#ignoreSubscription(org.omg.dds.core.InstanceHandle)},
   * and
   * {@link org.omg.dds.domain.DomainParticipant#ignoreTopic(org.omg.dds.core.InstanceHandle)}
   * these QoS can assist an application to define and enforce its own security
   * policies. The use of this QoS is not limited to security, rather it offers
   * a simple, yet flexible extensibility mechanism.
   */
  public interface UserData
  extends QosPolicy.ForDomainParticipant,
          QosPolicy.ForDataReader,
          QosPolicy.ForDataWriter
  {
      /**
       * Get a copy of the data.
       */
      public byte[] getValue();
  
  
      // --- Modification: -----------------------------------------------------
  
      /**
       * Copy this policy and override the value of the property.
       * @param value        A sequence of bytes that holds the application user data. By default, the sequence has length 0.
       * @param offset       Not used can have any int value.
       * @param length       Not used can have any int value.
       * @return  a new policy
       */
      public UserData withValue(byte value[], int offset, int length);
  }
  