/*
* This library is part of OpenCms -
* the Open Source Content Management System
*
* Copyright (c) Alkacon Software GmbH (http://www.alkacon.com)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* For further information about Alkacon Software GmbH, please see the
* company website: http://www.alkacon.com
*
* For further information about OpenCms, please see the
* project website: http://www.opencms.org
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package org.opencms.loader;
import org.opencms.configuration.I_CmsConfigurationParameterHandler;
import org.opencms.file.CmsObject;
import org.opencms.file.CmsResource;
import org.opencms.main.CmsException;
import java.io.IOException;
import java.util.Locale;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* This interface describes a resource loader for OpenCms,
* a class that can load a resource from the VFS,
* process it's contents and deliver the result to the user.<p>
*
* The I_CmsResourceLoader operates with Request and Response in
* much the same way as a standard Java web application.<p>
*
* This interface uses a standard servlet
* {@link javax.servlet.http.HttpServletRequestWrapper} / {@link javax.servlet.http.HttpServletResponseWrapper}
* that provide access to a special implementation of the {@link javax.servlet.RequestDispatcher}.
* The handling of the output written to the response is done by this
* dispatcher. The results are then passed back to OpenCms which
* will deliver them to the requesting user.<p>
*
* @since 6.0.0
*
* @see org.opencms.flex.CmsFlexRequest
* @see org.opencms.flex.CmsFlexResponse
* @see org.opencms.flex.CmsFlexRequestDispatcher
*/
public interface I_CmsResourceLoader extends I_CmsConfigurationParameterHandler {
/** Request parameter to force element selection. */
String PARAMETER_ELEMENT = "__element";
/**
* Destroys this ResourceLoder.<p>
*/
void destroy();
/**
* Dumps the processed content of the the requested file (and it's sub-elements) to a byte array.<p>
*
* Dumping the content is like calling "load" where the result is
* not written to the response stream, but to the returned byte array.
* Dumping is different from an export because the export might actually require
* that the content is handled or modified in a special way, or set special http headers.<p>
*
* Moreover, if the page type is template based, calling "dump" will not trigger the
* template but directly deliver the contents from the selected element.<p>
*
* @param cms used to access the OpenCms VFS
* @param resource the requested resource in the VFS
* @param element the element in the file to display
* @param locale the locale to display
* @param req the servlet request
* @param res the servlet response
*
* @return the content of the processed file
*
* @throws ServletException might be thrown by the servlet environment
* @throws IOException might be thrown by the servlet environment
* @throws CmsException in case of errors accessing OpenCms functions
*/
byte[] dump(
CmsObject cms,
CmsResource resource,
String element,
Locale locale,
HttpServletRequest req,
HttpServletResponse res) throws ServletException, IOException, CmsException;
/**
* Static exports the contents of the requested file and it's sub-elements.<p>
*
* During static export, the resource content may be written to 2 streams:
* The export stream, and the http response output stream.
* Which stream is actually used depends whether the export is in "on demand"
* or "after publish" mode. In "on demand" mode, the resource needs to
* be written both to the response stream and to the file stream. In
* "after publish" mode, it's usually only written to the file stream,
* but sometimes it's required to write to the response stream as well.<p>
*
* @param cms the initialized CmsObject which provides user permissions
* @param resource the requested OpenCms VFS resource
* @param req the servlet request
* @param res the servlet response
*
* @throws ServletException might be thrown in the process of including the sub element
* @throws IOException might be thrown in the process of including the sub element
* @throws CmsException in case something goes wrong
* @return the contents to export, or <code>null</code> if no export is required
*/
byte[] export(CmsObject cms, CmsResource resource, HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException, CmsException;
/**
* Returns the id of the ResourceLoader.<p>
*
* @return the id of the ResourceLoader
*/
int getLoaderId();
/**
* Returns a String describing the ResourceLoader.<p>
*
* @return a String describing the ResourceLoader
*/
String getResourceLoaderInfo();
/**
* Signals if the loader implementation supports static export of resources.<p>
*
* @return true if static export is supported, false otherwise
*/
boolean isStaticExportEnabled();
/**
* Signals if the loader implementation requires processing during static export of resources.<p>
*
* @return true if static export processing is required, false otherwise
*/
boolean isStaticExportProcessable();
/**
* Signals if the loader implementation is usable for creating templates.<p>
*
* @return true if the loader implementation is usable for creating templates, false otherwise
*/
boolean isUsableForTemplates();
/**
* Signals if a loader that supports templates must be invoked on the
* template URI or the resource URI.<p>
*
* @return true if the resource URI is to be used, false if the template URI is to be used
*/
boolean isUsingUriWhenLoadingTemplate();
/**
* Basic top-page processing method for a I_CmsResourceLoader,
* this method is called if the page is called as a sub-element
* on a page not already loaded with a I_CmsResourceLoader.<p>
*
* @param cms the initialized CmsObject which provides user permissions
* @param resource the requested OpenCms VFS resource
* @param req the servlet request
* @param res the servlet response
*
* @throws ServletException might be thrown by the servlet environment
* @throws IOException might be thrown by the servlet environment
* @throws CmsException in case of errors accessing OpenCms functions
*
* @see #service(CmsObject, CmsResource, ServletRequest, ServletResponse)
*/
void load(CmsObject cms, CmsResource resource, HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException, CmsException;
/**
* Does the job of including the requested resource,
* this method is called directly if the element is
* called as a sub-element from another I_CmsResourceLoader.<p>
*
* @param cms used to access the OpenCms VFS
* @param resource the requested resource in the VFS
* @param req the servlet request
* @param res the servlet response
*
* @throws ServletException might be thrown by the servlet environment
* @throws IOException might be thrown by the servlet environment
* @throws CmsException in case of errors accessing OpenCms functions
*
* @see org.opencms.flex.CmsFlexRequestDispatcher
*/
void service(CmsObject cms, CmsResource resource, ServletRequest req, ServletResponse res)
throws ServletException, IOException, CmsException;
}