3 ms·

Other than general traffic data compression, I've always been somewhat interested in html compression in particular. I know lots of webservers zip their respon

Other than general traffic data compression, I've always been somewhat interested in html compression in particular. I know lots of webservers zip their response data, but I was always curious about the things in html that show up very often and if there's a way to optimize around that. For example, most web xml data contains a lot of common tags, like "div" and "span" and others that are specific to html. I think if you add them up, they might make up a considerable percent of traffic data. Is it possible for the web server to swap those out for a single character before it sends the data, and have the browser replace it when it arrives? Or does zip compression already do that somehow?

wisty 14y ago
Yeees, no. Zip will replace the common tags (like "div") with a single "div" (in the compression dictionary), then a single character every time it appears (more or less - it might be less than a single byte if it's a really common tag). So there'll be a wasted overhead of a dictionary of common tags (which is kind of wasted). It would be more efficient if both the browsers and compression algorithms could agree (beforehand) had a dictionary of common terms which would be likely to appear in the document. If you're compressing a lot of data which is likely to be similar, you can do this with a common dictionary. See - http://stackoverflow.com/questions/479218/how-to-compress-small-strings http://stackoverflow.com/questions/479218/how-to-compress-sm... Of course, my answer on Stackoverflow is pretty crude. You could create a dictionary used to compress the compression dictionary. Google is probably going to do this any time soon (if they haven't already) since they control the client (Chrome), server (google web server) and protocol (SPDY).

3 ms·

Other than general traffic data compression, I've always been somewhat interested in html compression in particular. I know lots of webservers zip their respon

by tuxidomasx 14y ago

wisty 14y ago
Yeees, no. Zip will replace the common tags (like "div") with a single "div" (in the compression dictionary), then a single character every time it appears (more or less - it might be less than a single byte if it's a really common tag). So there'll be a wasted overhead of a dictionary of common tags (which is kind of wasted). It would be more efficient if both the browsers and compression algorithms could agree (beforehand) had a dictionary of common terms which would be likely to appear in the document. If you're compressing a lot of data which is likely to be similar, you can do this with a common dictionary. See - http://stackoverflow.com/questions/479218/how-to-compress-small-strings http://stackoverflow.com/questions/479218/how-to-compress-sm... Of course, my answer on Stackoverflow is pretty crude. You could create a dictionary used to compress the compression dictionary. Google is probably going to do this any time soon (if they haven't already) since they control the client (Chrome), server (google web server) and protocol (SPDY).