/*************************************************************************

"FreePastry" Peer-to-Peer Application Development Substrate 

Copyright 2002, Rice University. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

- Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.

- Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.

- Neither  the name  of Rice  University (RICE) nor  the names  of its
contributors may be  used to endorse or promote  products derived from
this software without specific prior written permission.

This software is provided by RICE and the contributors on an "as is"
basis, without any representations or warranties of any kind, express
or implied including, but not limited to, representations or
warranties of non-infringement, merchantability or fitness for a
particular purpose. In no event shall RICE or contributors be liable
for any direct, indirect, incidental, special, exemplary, or
consequential damages (including, but not limited to, procurement of
substitute goods or services; loss of use, data, or profits; or
business interruption) however caused and on any theory of liability,
whether in contract, strict liability, or tort (including negligence
or otherwise) arising in any way out of the use of this software, even
if advised of the possibility of such damage.

********************************************************************************/

package rice.p2p.past;

import rice.*;
import rice.environment.Environment;
import rice.p2p.commonapi.*;
import rice.p2p.past.rawserialization.*;

/**
 * @(#) Past.java This interface is exported by all instances of Past. An
 * instance of Past provides a distributed hash table (DHT) service. Each
 * instance stores tuples consisting of a key and an object of a particular
 * type, which must implement the interface PastContent. Past is event-driven,
 * so all methods are asynchronous and receive their results using the command
 * pattern.
 *
 * @version $Id: Past.java 3274 2006-05-15 16:17:47Z jeffh $
 * @author Alan Mislove
 * @author Ansley Post
 * @author Peter Druschel
 */
public interface Past {

  /**
   * Inserts an object with the given ID into this instance of Past.
   * Asynchronously returns a PastException to command, if the operation was
   * unsuccessful. If the operation was successful, a Boolean[] is returned
   * representing the responses from each of the replicas which inserted the
   * object.
   *
   * @param obj the object to be inserted
   * @param command Command to be performed when the result is received
   */
  public void insert(PastContent obj, Continuation command);

  /**
   * Retrieves the object stored in this instance of Past with the given ID.
   * Asynchronously returns a PastContent object as the result to the provided
   * Continuation, or a PastException. This method is provided for convenience;
   * its effect is identical to a lookupHandles() and a subsequent fetch() to
   * the handle that is nearest in the network. The client must authenticate the
   * object. In case of failure, an alternate replica of the object can be
   * obtained via lookupHandles() and fetch(). This method is not safe if the
   * object is immutable and storage nodes are not trusted. In this case,
   * clients should used the lookUpHandles method to obtains the handles of all
   * primary replicas and determine which replica is fresh in an
   * application-specific manner. By default, this method attempts to cache the
   * result locally for future use. Applications which do not desire this
   * behavior should use the lookup(id, boolean, command) method.
   *
   * @param id the key to be queried
   * @param command Command to be performed when the result is received
   */
  public void lookup(Id id, Continuation command);

  /**
   * Retrieves the object stored in this instance of Past with the given ID.
   * Asynchronously returns a PastContent object as the result to the provided
   * Continuation, or a PastException. This method is provided for convenience;
   * its effect is identical to a lookupHandles() and a subsequent fetch() to
   * the handle that is nearest in the network. The client must authenticate the
   * object. In case of failure, an alternate replica of the object can be
   * obtained via lookupHandles() and fetch(). This method is not safe if the
   * object is immutable and storage nodes are not trusted. In this case,
   * clients should used the lookUpHandles method to obtains the handles of all
   * primary replicas and determine which replica is fresh in an
   * application-specific manner. This method also allows applications to
   * specify if the result should be cached locally.
   *
   * @param id the key to be queried
   * @param cache Whether or not the result should be cached
   * @param command Command to be performed when the result is received
   */
  public void lookup(Id id, boolean cache, Continuation command);

  /**
   * Retrieves the handles of up to max replicas of the object stored in this
   * instance of Past with the given ID. Asynchronously returns an array of
   * PastContentHandles as the result to the provided Continuation, or a
   * PastException. Each replica handle is obtained from a different primary
   * storage root for the the given key. If max exceeds the replication factor r
   * of this Past instance, only r replicas are returned. This method will
   * return a PastContentHandle[] array containing all of the handles.
   *
   * @param id the key to be queried
   * @param max the maximal number of replicas requested
   * @param command Command to be performed when the result is received
   */
  public void lookupHandles(Id id, int max, Continuation command);

  /**
   * Retrieves the handle for the given object stored on the requested node.
   * Asynchronously returns a PostContentHandle (or null) to the provided
   * continuation.
   *
   * @param id the key to be queried
   * @param handle The node on which the handle is requested
   * @param command Command to be performed when the result is received
   */
  public void lookupHandle(Id id, NodeHandle handle, Continuation command);

  /**
   * Retrieves the object associated with a given content handle. Asynchronously
   * returns a PastContent object as the result to the provided Continuation, or
   * a PastException. The client must authenticate the object. In case of
   * failure, an alternate replica can be obtained using a different handle
   * obtained via lookupHandles().
   *
   * @param handle the key to be queried
   * @param command Command to be performed when the result is received
   */
  public void fetch(PastContentHandle handle, Continuation command);

  /**
   * get the nodeHandle of the local Past node
   *
   * @return the nodehandle
   */
  public NodeHandle getLocalNodeHandle();

  /**
   * Returns the number of replicas used in this Past
   *
   * @return the number of replicas for each object
   */
  public int getReplicationFactor();

  /**
   * Gets the Environment attribute of the Past object
   *
   * @return The Environment value
   */
  public Environment getEnvironment();

  /**
   * @return
   */
  public String getInstance();

  /**
   * Sets the ContentDeserializer attribute of the Past object
   *
   * @param deserializer The new ContentDeserializer value
   */
  public void setContentDeserializer(PastContentDeserializer deserializer);

  /**
   * Sets the ContentHandleDeserializer attribute of the Past object
   *
   * @param deserializer The new ContentHandleDeserializer value
   */
  public void setContentHandleDeserializer(PastContentHandleDeserializer deserializer);

}

