Re: General use of rewrite / redirect

On 18 Mar 2008, at 14:08, Aschwin Wesselius wrote:

Per Jessen wrote:

header(location) mechanisms do come with a very huge disadvantage if you don't use them with caution. Requests are reinitialised, libraries loaded (again), DB connections setup/checked again, session lookups are being done, log write for another request etc. That's quite an impact for just not knowing what to do with flow.

I'm having difficulties following you - a plain 303 redirect to a "Thank you" page shouldn't cause all of that. It's an HTTP reply with the 303 and the new URL, followed by a single URL request from the browser.

OK. I think I know how other people (like you) think about just requesting URL's one after another. If that's not such a performance issue for you, fine. A plain 303 redirect mostly isn't just a HTML file, it's another script (or the same script with another action falling through a switch statement, whatever). Point is: why hitting you webserver with multiple requests per user, just after submitting a form or whatever caused the redirect? If you have 2 users per day, that won't hurt. But if you have 30.000 concurrent users a minute, that could be 60.000 requests (besides all the images, stylesheets, javascripts that are being re-requested). Or am I talking nonsense?

What Per is saying is that you should be doing the minimum amount of work possible to handle each request. If you have a shedload of code that runs for every single page request regardless of what it's going to do then your architecture sucks. If that is the case then avoiding unnecessary bounces off the client is probably a good idea. If your site is well-architected then redirects of this type will probably not be a big performance drain. One minor thing... a 303 redirect is permanent. In this situation you want to use a 302 otherwise you could potentially cause problems with proxies. My opinion is that a redirect is the best way to prevent duplicate posts. It prevents the user from getting the confusing popup and it means you don't need to track whether a form has been posted yet. If your application is well-architected you shouldn't need to worry about performance. -Stut -- http://stut.net/