package edu.vt.marian.search;

import java.io.*;
import java.util.*;

import edu.vt.marian.common.*;


/** A class manager (sometimes called a class factory) is an object within
		MARIAN that is responsible for creating, storing, and searching on all
		digital information objects within some MARIAN class.  All class managers
		are either link class managers or node (DigInfObj) managers.  It is
		in the latter two classes that all the interesting methods get defined.
	<P>
		Two aspects of class management are hidden within these three simple
		interfaces:  caching and subclass management.
	<P>
		Caching is an aspect
		of the search methods.  We expect search requests to be repeated in the
		context of real running digital library systems.  We take advantage of
		this and speed things up by providing a cache of match sets in each manager
		indexed by search description.
	<P>
		Subclass management occurs when a MARIAN class is defined as a superclass
		of other MARIAN classes.  In this case, the manager for the superclass
		is responsible to take all requests, pass them to each subclass, and
		assemble their responses together with any response from objects of this
		class proper.  At the current stage of implementation (MARIAN v.2.1),
		class managers are implemented as <I>either</I> subclass managers <I>or</I>
		managers of objects.  In otherwords, managers for superclasses do not
		"own" any objects of their own, and classes that directly manage objects
		do not have subclasses.  This may change in later development.
	<P>
	JDK Version  : 1.1.5
    <P>
    @author	Robert France
    @see	NodeClassManager
    @see	LinkClassManager
*/


public interface ClassManager
{
	/**
	    Return codes specific to class managers.
	 */
	public final static int NO_SUCH_OBJECT = -11;	// Not currently in this class.
	public final static int ALREADY_EXISTS = -12;	// Can't add:  already here.


	/**
		How many objects are in this class?
	*/
	public long classSize();

};