/**
 * <copyright> Copyright 2006 by Know-Center, Graz, Austria </copyright>
 * PDF-AS has been contracted by the E-Government Innovation Center EGIZ, a
 * joint initiative of the Federal Chancellery Austria and Graz University of
 * Technology.
 *
 * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 * http://www.osor.eu/eupl/
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing permissions and
 * limitations under the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text
 * file for details on the various modules and licenses.
 * The "NOTICE" text file is part of the distribution. Any derivative works
 * that you distribute must include a readable copy of the "NOTICE" text file.
 */
package at.knowcenter.wag.egov.egiz.sig;

import at.gv.egiz.pdfas.framework.input.DataSource;

/**
 * This encapsuilates the content data to be signed or verified.
 * 
 * <p>
 * For a text signature this would be the text to be signed or verified. For a
 * binary signature this would be the PDF to be signed or verified.
 * </p>
 * 
 * <p>
 * This is an abstract reprsenation of data: the binary data, its mime type and
 * (if appropriate according to the mime type) the charset the data is encoded.
 * </p>
 * 
 * @author wprinz
 */
public interface SignatureData
{
  /**
   * Returns the DataSource that provides the data for this SignatureData.
   * 
   * @return Returns the DataSource.
   */
  public DataSource getDataSource();

  /**
   * Returns the mime type of the data.
   * 
   * <p>
   * E.g. "text/plain" for text data or "application/pdf" for a PDF.
   * </p>
   * 
   * @return Returns the mime type of the data.
   */
  public String getMimeType();

  /**
   * Returns the character encoding (charset) of the data if appropriate.
   * 
   * <p>
   * This is only appropriate if the mime type suggests that the data contained
   * in here is textually encoded. Usually text/plain or similar data types will
   * have a character encoding present.
   * </p>
   * <p>
   * If no character encoding is present, null is returned here.
   * </p>
   * <p>
   * E.g. "UTF-8" is the most common encoding for textual data.
   * </p>
   * 
   * @return Returns the character encoding (charset) of the data if
   *         appropriate.
   */
  public String getCharacterEncoding();
}