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> it is possible to flag individual scan layers of progressive JPEGs with high priority and making the server push those scan layers into the client browsers’ P

> it is possible to flag individual scan layers of progressive JPEGs with high priority and making the server push those scan layers into the client browsers’ Push cache even before the request for the respective image is initiated Whoa - I had no idea this is possible. Isn't this a crazy layering violation (why should HTTP2 know about progressive JPEGs)? The links don't seem to provide any more information about it. edit It looks like HTTP2 only talks about streams. So it's too strong to say that you can flag "individual scan layers with high priority." You can't change the order of scan layers within a JPEG file, or send the file in anything except its natural byte order. So it seems like this has the same limitations as HTTP 1.x.

the8472 10y ago
It's only a violation if you don't have a clearly structured API to provide the necessary hints from the application to the HTTP server.
- millstone 10y ago
  How can a layering violation in a protocol be fixed at the API level? An API is what it is; a good API atop a gross protocol is only lipstick on a pig.
  - mnarayan01 10y ago
    I think he's saying that you could potentially have the prioritized output without "HTTP2 know[ing] about progressive JPEGs". E.g. specifying "these layers are high priority" versus "the first n bytes of this stream are high priority": The first would be a layering violation, but I don't see any reason the second would be (not saying anything about its practicality). Now obviously the protocol would need to support the second (at least to use it in the context we're talking about), but I read the GP as using "API" figuratively enough to encompass this.
    - the8472 10y ago
      Yes. And would pushing chunks actually require a protocol modification? AIUI http2 push mirrors the hypothetical request headers. So it could essentially push a range-request which the browser could use to partially populate its cache.
sedatk 10y ago
i don't think it's specific to a file format.

the8472 10y ago

It's only a violation if you don't have a clearly structured API to provide the necessary hints from the application to the HTTP server.

millstone 10y ago
How can a layering violation in a protocol be fixed at the API level? An API is what it is; a good API atop a gross protocol is only lipstick on a pig.
- mnarayan01 10y ago
  I think he's saying that you could potentially have the prioritized output without "HTTP2 know[ing] about progressive JPEGs". E.g. specifying "these layers are high priority" versus "the first n bytes of this stream are high priority": The first would be a layering violation, but I don't see any reason the second would be (not saying anything about its practicality). Now obviously the protocol would need to support the second (at least to use it in the context we're talking about), but I read the GP as using "API" figuratively enough to encompass this.
  - the8472 10y ago
    Yes. And would pushing chunks actually require a protocol modification? AIUI http2 push mirrors the hypothetical request headers. So it could essentially push a range-request which the browser could use to partially populate its cache.

sedatk 10y ago

i don't think it's specific to a file format.