+ * If an error occurs during processing, the process method + * should throw an exception. The base class will log the exception + * and return an error message to Flash. + *
+ * We cannot use Struts actions as the WDDX packet is the + * complete contents POST body and Struts consumes the body + * before we can get to it. + *
+ * If this servlet receives a GET rather than a POST, then an + * error packet (in wddx format) will be returned. + *
+ * If the log level is set to debug, then the both the received packet + * and the reply packet will be logged. + * + * @author Fiona Malikoff + */ +public abstract class AbstractStoreWDDXPacketServlet extends HttpServlet { + + private static Logger log = Logger.getLogger(AbstractStoreWDDXPacketServlet.class); + /** + * @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest, HttpServletResponse) + */ + protected void doGet(HttpServletRequest request, HttpServletResponse response) + throws ServletException, IOException { + Writer writer = response.getWriter(); + FlashMessage flashMessage = FlashMessage.getWDDXPacketGetReceived(getMessageKey(null,request)); + writer.write(flashMessage.serializeMessage()); + } + + /** + * @see javax.servlet.http.HttpServlet#doPost(HttpServletRequest, HttpServletResponse) + */ + protected void doPost(HttpServletRequest request, HttpServletResponse response) + throws IOException + { + + PrintWriter writer = null; + String packet = null; + String replyPacket = null; + try { + writer = response.getWriter(); + + packet = getBody(request); + if ( log.isDebugEnabled() ) { + log.debug("Request "+request.getRequestURI()+" received packet "+packet); + } + + replyPacket = process(packet, request); + + if ( log.isDebugEnabled() ) { + log.debug("Request "+request.getRequestURI()+" sending back packet "+replyPacket); + } + + } catch ( Exception e ) { + // Don't want exceptions flowing back to Flash if we can help it. + String uri = request.getRequestURI(); + log.error(uri+" request triggered exception ",e); + + FlashMessage flashMessage = FlashMessage.getExceptionOccured(getMessageKey(packet,request), + e.getMessage()!=null?e.getMessage():""); + writer.write(flashMessage.serializeMessage()); + return; + } + + // can't inform Flash if an exception occurs now... + if ( writer != null ) + writer.println(replyPacket); + } + + /* Get the post body */ + private String getBody(HttpServletRequest req) + throws IOException + { + BufferedReader tempReader = req.getReader(); + int tempContentLength = req.getContentLength(); + StringBuffer tempStrBuf = new StringBuffer( tempContentLength>0 ? tempContentLength : 200 ); + String tempStr; + tempStr = tempReader.readLine(); + while ( tempStr != null ) + { + tempStrBuf.append(tempStr); + tempStr = tempReader.readLine(); + } + + return(tempStrBuf.toString()); + } + + /** + * Process the packet received from Flash. + *
+ * If an error occurs, this method should throw an exception + * so that the base class will log the exception and return an error message + * to Flash. + * @return A string which is a WDDX packet containing a FlashMessage. + */ + abstract protected String process(String packet, HttpServletRequest request) + throws Exception; + + /** + * Get the "name" of the servlet. This must match the name + * that is returned in the messageKey section of the FlashMessage + * when the packet is successfully stored. + *
+ * If an exception is thrown by process(), the base class + * generates an error packet to send back to Flash. It will include + * this messageKey in the error message, so that the Flash client + * can match the error to the call. + * @return messageKey + */ + abstract protected String getMessageKey(String packet, HttpServletRequest request); +}