/*

 * Copyright (c) 2005, 2014, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed 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.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

/*

 * $Id: RetrievalMethod.java,v 1.8 2005/05/10 16:35:35 mullan Exp $

 */

package javax.xml.crypto.dsig.keyinfo;

import javax.xml.crypto.Data;

import javax.xml.crypto.URIReference;

import javax.xml.crypto.URIReferenceException;

import javax.xml.crypto.XMLCryptoContext;

import javax.xml.crypto.XMLStructure;

import javax.xml.crypto.dsig.Transform;

import java.util.List;

/**

 * A representation of the XML <code>RetrievalMethod</code> element as

 * defined in the <a href="http://www.w3.org/TR/xmldsig-core/">

 * W3C Recommendation for XML-Signature Syntax and Processing</a>.

 * A <code>RetrievalMethod</code> object is used to convey a reference to

 * <code>KeyInfo</code> information that is stored at another location.

 * The XML schema definition is defined as:

 *

 * <pre>

 *   <element name="RetrievalMethod" type="ds:RetrievalMethodType"/>

 *   <complexType name="RetrievalMethodType">

 *     <sequence>

 *       <element name="Transforms" type="ds:TransformsType" minOccurs="0"/>

 *     </sequence>

 *     <attribute name="URI" type="anyURI"/>

 *     <attribute name="Type" type="anyURI" use="optional"/>

 *   </complexType>

 * </pre>

 *

 * A <code>RetrievalMethod</code> instance may be created by invoking one of the

 * {@link KeyInfoFactory#newRetrievalMethod newRetrievalMethod} methods

 * of the {@link KeyInfoFactory} class, and passing it the URI

 * identifying the location of the KeyInfo, an optional type URI identifying

 * the type of KeyInfo, and an optional list of {@link Transform}s; for example:

 * <pre>

 *   KeyInfoFactory factory = KeyInfoFactory.getInstance("DOM");

 *   RetrievalMethod rm = factory.newRetrievalMethod

 *      ("#KeyValue-1", KeyValue.DSA_TYPE, Collections.singletonList(Transform.BASE64));

 * </pre>

 *

 * @author Sean Mullan

 * @author JSR 105 Expert Group

 * @since 1.6

 * @see KeyInfoFactory#newRetrievalMethod(String)

 * @see KeyInfoFactory#newRetrievalMethod(String, String, List)

 */

public interface RetrievalMethod extends URIReference, XMLStructure {

    /**

     * Returns an {@link java.util.Collections#unmodifiableList unmodifiable

     * list} of {@link Transform}s of this <code>RetrievalMethod</code>.

     *

     * @return an unmodifiable list of <code>Transform</code> objects (may be

     *    empty but never <code>null</code>).

     */

    List<Transform> getTransforms();

    /**

     * Returns the URI of the referenced <code>KeyInfo</code> information.

     *

     * @return the URI of the referenced <code>KeyInfo</code> information in

     *    RFC 2396 format (never <code>null</code>)

     */

    String getURI();

   /**

    * Dereferences the <code>KeyInfo</code> information referenced by this

    * <code>RetrievalMethod</code> and applies the specified

    * <code>Transform</code>s.

    *

    * @param context an <code>XMLCryptoContext</code> that may contain

    *    additional useful information for dereferencing the URI. The

    *    context's <code>baseURI</code> and <code>dereferencer</code>

    *    parameters (if specified) are used to resolve and dereference this

    *    <code>RetrievalMethod</code>

    * @return a <code>Data</code> object representing the raw contents of the

    *    <code>KeyInfo</code> information referenced by this

    *    <code>RetrievalMethod</code>. It is the caller's responsibility to

    *    convert the returned data to an appropriate

    *    <code>KeyInfo</code> object.

    * @throws NullPointerException if <code>context</code> is <code>null</code>

    * @throws URIReferenceException if there is an error while dereferencing

    */

    Data dereference(XMLCryptoContext context) throws URIReferenceException;

}