Unless you have mapped all *.jsp URLs to the Struts ActionServlet in your web.xml, your link will not go through the Struts framework.
See example of how you would map a URL
pattern to the ActionServlet at
http://www.reumann.net/do/struts/lesson1/step7) You need your link to go through an Action, e.g. via /update.do in which case I wouldn't think
you should need a request parameter. At any rate, you can still put a parameter, e.g. /update.do?from=update if you really want to (doesn't that seem redundant to you though?). The Action mapped to update.do would need to be associated with an ActionForm that has the methods getFrom()/setFrom().
In the Action, you normally don't need to extract parameters from the request since those values have already been transferred into the ActionForm (and converted to the appropriate type) for you by Struts.
Go through the tutorial I cited above to get a good understanding of the basics.