lang/java/reef-wake/wake/src/main/java/org/apache/reef/wake/Identifier.java

/*
 * Licensed to 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 org.apache.reef.wake;

/**
 * An identifier class for REEF.  Identifiers are a generic naming primitive
 * that carry some information about the type of the object they point to.
 * Typical examples are server sockets, filenames, and requests.
 *
 * Identifier constructors should take zero arguments, or take a single string.
 */
public interface Identifier {

  /**
   * Returns a hash code for the object.
   *
   * @return a hash code value for this object
   */
  int hashCode();

  /**
   * Checks that another object is equal to this object.
   *
   * @param o another object
   * @return true if the object is the same as the object argument; false,
   * otherwise
   */
  boolean equals(Object o);

  /**
   * Return a string representation of this object. This method should return a
   * URL-style string, that begins with "type://", where "type" is chosen to
   * uniquely identify this type of identifier.
   */
  String toString();

}