Re: [scalability, performance, DoS] To or not to process images at runtime

Marcelo de Moraes Serpa wrote: > Less manegeable becouse I would have to keep copies of the pictures on > the disk. If I ever want to change these watermarks, I would have to > somehow recreate them. It is more work to do than if I used the > per-request runtime applying of watermark approach, since in this > case, I would just apply the watermarks I wanted and then serve the > stream directly from memory. Hmm, I don't usually think "more work" = "less managable", but that's a matter for you. My personal take on this type of thing - I would go for the on-demand watermarking, but with a cached copy of everything that is watermarked. "on-demand" = "when a photo is published the first time". Like Bernhard said earlier, it probably takes a few milliseconds to apply a watermark, so the very first time a photo is viewed, the viewer might just experience the slightest delay. With apache this is really easy to do: RewriteEngine on RewriteCond %{REQUEST_FILENAME} !-s RewriteRule ^(.+)$ apply_watermark.php?name=$1 This means: if <photo-with-watermark> doesn't exist, run "apply-watermark.php" to apply a watermark, write the <photo-with-watermark> to cache/disk, and then output the watermarked photo. If you need to change the watermark, just erase the cached copies and they're regenerated next time someone wants to view a photo. To save on disk-space if that is a concern, you can run regular purges of cached copies that haven't been viewed for a while: find <cachedir> -atime +30 -type f | xargs rm /Per Jessen, Zürich