iworkloadstorable.java

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package com.heaton.bot;

/**
 * This interface defines a class that can
 * be used to store a spider's workload.
 * The Bot package currently supports two
 * different workload stores:
 *
 * SpiderInternalWorkload - Stores the
 *   contents of the workload in memory.
 *
 * SpiderSQLWorkload - Stores the contents
 *   of the workload in an SQL database.
 *
 * Copyright 2001-2003 by Jeff Heaton (http://www.jeffheaton.com)
 *
 * @author Jeff Heaton
 * @version 1.2
 */
public interface IWorkloadStorable {

  /**
   * A workload entry has a status of running
   * if the spider worker is opening or downloading
   * that page. This state usually goes to COMPLETE
   * or ERROR.
   */
  public static final char RUNNING = 'R';

  /**
   * Processing of this URL resulted in an
   * error.
   */
  public static final char ERROR = 'E';

  /**
   * This URL is waiting for a spider
   * worker to take it on.
   */
  public static final char WAITING = 'W';

  /**
   * This page is complete and should not
   * be redownloaded.
   */
  public static final char COMPLETE = 'C';

  /**
   * The status is unknown.
   */
  public static final char UNKNOWN = 'U';

  /**
   * Call this method to request a URL
   * to process. This method will return
   * a WAITING URL and mark it as RUNNING.
   *
   * @return The URL that was assigned.
   */
  public String assignWorkload();

  /**
   * Add a new URL to the workload, and
   * assign it a status of WAITING.
   *
   * @param url The URL to be added.
   */
  public void addWorkload(String url);

  /**
   * Called to mark this URL as either
   * COMPLETE or ERROR.
   *
   * @param url The URL to complete.
   * @param error true - assign this workload a status of ERROR.
   * false - assign this workload a status of COMPLETE.
   */
  public void completeWorkload(String url,boolean error);

  /**
   * Get the status of a URL.
   *
   * @param url Returns either RUNNING, ERROR
   * WAITING, or COMPLETE. If the URL
   * does not exist in the database,
   * the value of UNKNOWN is returned.
   * @return Returns either RUNNING,ERROR,
   * WAITING,COMPLETE or UNKNOWN.
   */
  public char getURLStatus(String url);

  /**
   * Clear the contents of the workload store.
   */
  public void clear();
}