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/*

 * 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

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 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

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package com.sun.org.apache.xerces.internal.impl;

import java.io.IOException;

import com.sun.org.apache.xerces.internal.xni.XNIException;

import com.sun.org.apache.xerces.internal.xni.grammars.XMLDTDDescription;

import com.sun.org.apache.xerces.internal.xni.parser.XMLEntityResolver;

import com.sun.org.apache.xerces.internal.xni.parser.XMLInputSource;

/**

 * <p>This interface extends <code>XMLEntityResolver</code> providing

 * a method to resolve external subsets for documents which do not

 * explicitly provide one. The application can register an object that

 * implements this interface with the parser configuration. If registered,

 * it will be queried to locate an external subset when none is provided,

 * even for documents that do not contain DOCTYPE declarations. If the

 * registered external subset resolver does not provide an external subset

 * for a given document, it should return <code>null</code>.</p>

 *

 * @xerces.internal

 *

 * @author Michael Glavassevich, IBM

 *

 */

public interface ExternalSubsetResolver

    extends XMLEntityResolver {

    //

    // ExternalSubsetResolver methods

    //

    /**

     * <p>Locates an external subset for documents which do not explicitly

     * provide one. If no external subset is provided, this method should

     * return <code>null</code>.</p>

     *

     * @param grammarDescription a description of the DTD

     *

     * @throws XNIException Thrown on general error.

     * @throws IOException  Thrown if resolved entity stream cannot be

     *                      opened or some other i/o error occurs.

     */

    public XMLInputSource getExternalSubset(XMLDTDDescription grammarDescription)

        throws XNIException, IOException;

} // interface ExternalSubsetResolver