/*
 * Copyright (c) 2004 World Wide Web Consortium,
 *
 * (Massachusetts Institute of Technology, European Research Consortium for
 * Informatics and Mathematics, Keio University). All Rights Reserved. This
 * work is distributed under the W3C(r) Software License [1] in the hope that
 * it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
 */

package org.w3c.dom.ls;

/**
 *  <code>LSResourceResolver</code> provides a way for applications to 
 * redirect references to external resources. 
 * <p> Applications needing to implement custom handling for external 
 * resources can implement this interface and register their implementation 
 * by setting the "resource-resolver" parameter of 
 * <code>DOMConfiguration</code> objects attached to <code>LSParser</code> 
 * and <code>LSSerializer</code>. It can also be register on 
 * <code>DOMConfiguration</code> objects attached to <code>Document</code> 
 * if the "LS" feature is supported. 
 * <p> The <code>LSParser</code> will then allow the application to intercept 
 * any external entities, including the external DTD subset and external 
 * parameter entities, before including them. The top-level document entity 
 * is never passed to the <code>resolveResource</code> method. 
 * <p> Many DOM applications will not need to implement this interface, but it 
 * will be especially useful for applications that build XML documents from 
 * databases or other specialized input sources, or for applications that 
 * use URNs. 
 * <p ><b>Note:</b>  <code>LSResourceResolver</code> is based on the SAX2 [<a href='http://www.saxproject.org/'>SAX</a>] <code>EntityResolver</code> 
 * interface. 
 * <p>See also the <a href='http://www.w3.org/TR/2004/REC-DOM-Level-3-LS-20040407'>Document Object Model (DOM) Level 3 Load
and Save Specification</a>.
 */
public interface LSResourceResolver {
    /**
     *  Allow the application to resolve external resources. 
     * <br> The <code>LSParser</code> will call this method before opening any 
     * external resource, including the external DTD subset, external 
     * entities referenced within the DTD, and external entities referenced 
     * within the document element (however, the top-level document entity 
     * is not passed to this method). The application may then request that 
     * the <code>LSParser</code> resolve the external resource itself, that 
     * it use an alternative URI, or that it use an entirely different input 
     * source. 
     * <br> Application writers can use this method to redirect external 
     * system identifiers to secure and/or local URI, to look up public 
     * identifiers in a catalogue, or to read an entity from a database or 
     * other input source (including, for example, a dialog box). 
     * @param type  The type of the resource being resolved. For XML [<a href='http://www.w3.org/TR/2004/REC-xml-20040204'>XML 1.0</a>] resources 
     *   (i.e. entities), applications must use the value 
     *   <code>"http://www.w3.org/TR/REC-xml"</code>. For XML Schema [<a href='http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/'>XML Schema Part 1</a>]
     *   , applications must use the value 
     *   <code>"http://www.w3.org/2001/XMLSchema"</code>. Other types of 
     *   resources are outside the scope of this specification and therefore 
     *   should recommend an absolute URI in order to use this method. 
     * @param namespaceURI  The namespace of the resource being resolved, 
     *   e.g. the target namespace of the XML Schema [<a href='http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/'>XML Schema Part 1</a>]
     *    when resolving XML Schema resources. 
     * @param publicId  The public identifier of the external entity being 
     *   referenced, or <code>null</code> if no public identifier was 
     *   supplied or if the resource is not an entity. 
     * @param systemId  The system identifier, a URI reference [<a href='http://www.ietf.org/rfc/rfc2396.txt'>IETF RFC 2396</a>], of the 
     *   external resource being referenced, or <code>null</code> if no 
     *   system identifier was supplied. 
     * @param baseURI  The absolute base URI of the resource being parsed, or 
     *   <code>null</code> if there is no base URI. 
     * @return  A <code>LSInput</code> object describing the new input 
     *   source, or <code>null</code> to request that the parser open a 
     *   regular URI connection to the resource. 
     */
    public LSInput resolveResource(String type, 
                                   String namespaceURI, 
                                   String publicId, 
                                   String systemId, 
                                   String baseURI);

}