uk.ac.ebi.intenz.webapp.utilities
Class ControlFlowToken

java.lang.Object
  uk.ac.ebi.intenz.webapp.utilities.ControlFlowToken

public class ControlFlowToken
extends Object

This class provides a mechanism to guarantee correct control flow, that is using "back" or "reload" buttons of a browser do not lead to unwanted behaviour.

This is achieved by storing a unique token in the session and request when accessing a servlets service() method. The resulting pages of a servlet response contain the token by accessing it via the request object. Pressing the "back" or "reload" button leads to already generated pages with different tokens, therefore a subsequent processing action by a servlet will encounter the difference when comparing the token of the request with token of the current session and permit this transaction.

Version:

$Revision: 1.2 $ $Date: 2008/01/28 12:33:09 $

Author:

Michael Darsow

Constructor Summary

ControlFlowToken()

Method Summary

static boolean	isValid(javax.servlet.http.HttpServletRequest req) Returns true if the token is valid (request token == session token).
static void	setToken(javax.servlet.http.HttpServletRequest req, Long enzymeId) Sets a control flow token in the session and in the request.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ControlFlowToken

public ControlFlowToken()

Method Detail

setToken

public static void setToken(javax.servlet.http.HttpServletRequest req,
                            Long enzymeId)

Sets a control flow token in the session and in the request.

The token is a kind of checksum (MD5 message digest, part of java.security).

Parameters:

req - The request object.

isValid

public static boolean isValid(javax.servlet.http.HttpServletRequest req)

Returns true if the token is valid (request token == session token).

Parameters:

req - The request object.

Returns:

see above.