/*

 * Copyright (c) 2005, 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

 * or visit www.oracle.com if you need additional information or have any

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 */

/*

 * $Id: Transform.java,v 1.5 2005/05/10 16:03:48 mullan Exp $

 */

package javax.xml.crypto.dsig;

import java.io.OutputStream;

import java.security.spec.AlgorithmParameterSpec;

import javax.xml.crypto.AlgorithmMethod;

import javax.xml.crypto.Data;

import javax.xml.crypto.OctetStreamData;

import javax.xml.crypto.XMLCryptoContext;

import javax.xml.crypto.XMLStructure;

import javax.xml.crypto.dsig.spec.TransformParameterSpec;

/**

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

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

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

 * The XML Schema Definition is defined as:

 *

 * <pre>

 * <element name="Transform" type="ds:TransformType"/>

 *   <complexType name="TransformType" mixed="true">

 *     <choice minOccurs="0" maxOccurs="unbounded">

 *       <any namespace="##other" processContents="lax"/>

 *       <!-- (1,1) elements from (0,unbounded) namespaces -->

 *       <element name="XPath" type="string"/>

 *     </choice>

 *     <attribute name="Algorithm" type="anyURI" use="required"/>

 *   </complexType>

 * </pre>

 *

 * A <code>Transform</code> instance may be created by invoking the

 * {@link XMLSignatureFactory#newTransform newTransform} method

 * of the {@link XMLSignatureFactory} class.

 *

 * @author Sean Mullan

 * @author JSR 105 Expert Group

 * @since 1.6

 * @see XMLSignatureFactory#newTransform(String, TransformParameterSpec)

 */

public interface Transform extends XMLStructure, AlgorithmMethod {

    /**

     * The <a href="http://www.w3.org/2000/09/xmldsig#base64">Base64</a>

     * transform algorithm URI.

     */

    static final String BASE64 = "http://www.w3.org/2000/09/xmldsig#base64";

    /**

     * The <a href="http://www.w3.org/2000/09/xmldsig#enveloped-signature">

     * Enveloped Signature</a> transform algorithm URI.

     */

    static final String ENVELOPED =

        "http://www.w3.org/2000/09/xmldsig#enveloped-signature";

    /**

     * The <a href="http://www.w3.org/TR/1999/REC-xpath-19991116">XPath</a>

     * transform algorithm URI.

     */

    static final String XPATH = "http://www.w3.org/TR/1999/REC-xpath-19991116";

    /**

     * The <a href="http://www.w3.org/2002/06/xmldsig-filter2">

     * XPath Filter 2</a> transform algorithm URI.

     */

    static final String XPATH2 = "http://www.w3.org/2002/06/xmldsig-filter2";

    /**

     * The <a href="http://www.w3.org/TR/1999/REC-xslt-19991116">XSLT</a>

     * transform algorithm URI.

     */

    static final String XSLT = "http://www.w3.org/TR/1999/REC-xslt-19991116";

    /**

     * Returns the algorithm-specific input parameters associated with this

     * <code>Transform</code>.

     * <p>

     * The returned parameters can be typecast to a

     * {@link TransformParameterSpec} object.

     *

     * @return the algorithm-specific input parameters (may be <code>null</code>

     *    if not specified)

     */

    AlgorithmParameterSpec getParameterSpec();

    /**

     * Transforms the specified data using the underlying transform algorithm.

     *

     * @param data the data to be transformed

     * @param context the <code>XMLCryptoContext</code> containing

     *    additional context (may be <code>null</code> if not applicable)

     * @return the transformed data

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

     * @throws TransformException if an error occurs while executing the

     *    transform

     */

    public abstract Data transform(Data data, XMLCryptoContext context)

        throws TransformException;

    /**

     * Transforms the specified data using the underlying transform algorithm.

     * If the output of this transform is an <code>OctetStreamData</code>, then

     * this method returns <code>null</code> and the bytes are written to the

     * specified <code>OutputStream</code>. Otherwise, the

     * <code>OutputStream</code> is ignored and the method behaves as if

     * {@link #transform(Data, XMLCryptoContext)} were invoked.

     *

     * @param data the data to be transformed

     * @param context the <code>XMLCryptoContext</code> containing

     *    additional context (may be <code>null</code> if not applicable)

     * @param os the <code>OutputStream</code> that should be used to write

     *    the transformed data to

     * @return the transformed data (or <code>null</code> if the data was

     *    written to the <code>OutputStream</code> parameter)

     * @throws NullPointerException if <code>data</code> or <code>os</code>

     *    is <code>null</code>

     * @throws TransformException if an error occurs while executing the

     *    transform

     */

    public abstract Data transform

        (Data data, XMLCryptoContext context, OutputStream os)

        throws TransformException;

}