4 ms·

Are you describing http://en.wikipedia.org/wiki/HTTP_ETag http://en.wikipedia.org/wiki/HTTP_ETag or something different?

sophacles 16y ago
Apparently ETag, but you know, with people actually using it, and a standardized hashing mechanism (to reduce duplication of common elements across sites). (honestly I had never even heard of it before just now).
- psadauskas 16y ago
  All browsers take advantage of it. Not very many library http clients do, though. (I had to write my own, https://github.com/paul/resourceful https://github.com/paul/resourceful )
- riffraff 16y ago
  ommon elements are shared by using a single source (e.g. google's CDN for javascripts) but standardizing makes little sense imvho. For one, you can use an ETag without generating the page and hashing it if it only depends on a db-stored resource, and that is mightily application dependent.
  - sophacles 16y ago
    1) What does a CDN have to do with the simple real-world fact that content gets duplicated around sites all the time, particularly stupid crap like funny picture memes? A good global hash of this would certainly help optimize web-caching. 2) A well designed app will hopefully not have every page rendered dynamically at the server anymore, but just have an api to send data back to the page for rendering client side. This benefits from content caching (provided the content is big enough to benefit from caching rather than retransmission). 3. Using something like varnish in front of your site will allow you to dynamically invalidate the hash when needed, and in the interim, a generated result to a url is no different than a static one.
    - riffraff 16y ago
      1) that common stuff reused as-is (such as jquery) can be cached and reused by many, funny picture memes are usually resized, cropped, modified and I frankly do not see many of them, but I load jquery 200 times a day, it seems to me you want to optimize a non-bottleneck. 2) how do you send such content? suppose it's in the db, you need to convert it to a wire format (json or whatever) and then generate an hash for it, but you do not need to, you could just send a revision id as ETag without even reading the full data from the db 3) whatever you want to do with an hash, you can do using an hash as the etag. The latter is simply more generic
      - sophacles 16y ago
        1) You are doing browser level cache optimization and bike-shedding, I am looking at it from an ISP level. Once you have a big pipe and many users, things like this actually start to have a noticeable effect on bandwidth usage. Further, no matter what your use case, it has almost no bearing on the normal (statistically normal no digressions please) use case. 2) So I see what you are saying, but you are wrong -- the ETag still requires a lookup of "did content change since then, based on this tag". My system does not preclude a similar mapping of (tag value, last change) in the server. 3) Yeah, I know, my point is that a standardized hashing method for the ETag provides benefits on top of the ETag. Sometimes everyone playing nicely together actually works out better than lots of flexibility.

sophacles 16y ago

Apparently ETag, but you know, with people actually using it, and a standardized hashing mechanism (to reduce duplication of common elements across sites). (honestly I had never even heard of it before just now).

psadauskas 16y ago
All browsers take advantage of it. Not very many library http clients do, though. (I had to write my own, https://github.com/paul/resourceful https://github.com/paul/resourceful )
riffraff 16y ago
ommon elements are shared by using a single source (e.g. google's CDN for javascripts) but standardizing makes little sense imvho. For one, you can use an ETag without generating the page and hashing it if it only depends on a db-stored resource, and that is mightily application dependent.
- sophacles 16y ago
  1) What does a CDN have to do with the simple real-world fact that content gets duplicated around sites all the time, particularly stupid crap like funny picture memes? A good global hash of this would certainly help optimize web-caching. 2) A well designed app will hopefully not have every page rendered dynamically at the server anymore, but just have an api to send data back to the page for rendering client side. This benefits from content caching (provided the content is big enough to benefit from caching rather than retransmission). 3. Using something like varnish in front of your site will allow you to dynamically invalidate the hash when needed, and in the interim, a generated result to a url is no different than a static one.
  - riffraff 16y ago
    1) that common stuff reused as-is (such as jquery) can be cached and reused by many, funny picture memes are usually resized, cropped, modified and I frankly do not see many of them, but I load jquery 200 times a day, it seems to me you want to optimize a non-bottleneck. 2) how do you send such content? suppose it's in the db, you need to convert it to a wire format (json or whatever) and then generate an hash for it, but you do not need to, you could just send a revision id as ETag without even reading the full data from the db 3) whatever you want to do with an hash, you can do using an hash as the etag. The latter is simply more generic
    - sophacles 16y ago
      1) You are doing browser level cache optimization and bike-shedding, I am looking at it from an ISP level. Once you have a big pipe and many users, things like this actually start to have a noticeable effect on bandwidth usage. Further, no matter what your use case, it has almost no bearing on the normal (statistically normal no digressions please) use case. 2) So I see what you are saying, but you are wrong -- the ETag still requires a lookup of "did content change since then, based on this tag". My system does not preclude a similar mapping of (tag value, last change) in the server. 3) Yeah, I know, my point is that a standardized hashing method for the ETag provides benefits on top of the ETag. Sometimes everyone playing nicely together actually works out better than lots of flexibility.