Generic Bundling

Ilya Grigorik igrigorik at gmail.com
Fri Oct 25 20:39:56 PDT 2013


On Fri, Oct 25, 2013 at 12:17 AM, Andrea Giammarchi <
andrea.giammarchi at gmail.com> wrote:

> Ilya ... just to re-clarify what was the discussion about: Generic
> Bundling ... not HTTP Bundling.
> I don't know why many keep coupling and confining HTML5 over HTTP and
> nothing else.
> Bundling as you do with executables or apps, bundling as you send a single
> file update for your customer to replace instead of unzipping, overwriting
> each file, etcetera.
> Why is in your opinion bundling bad for non HTTP, offline, apps created
> using these technologies ?
> Every programming language I know have some bundle support that works as
> single package/file ... C has the executable, then we have phar, war, jar,
> python has many ... what about JS ? Won't work without HTTP ? Why ?
>

I'm not saying it won't work. I'm saying there are many downsides to
distributing large blobs of data. Case in point, once you start
distributing large blobs, you'll soon realize that it sucks that you have
to download the entire blob every time a single byte has changed. As a
result, you end up developing binary-diff formats.. like Courgette [1] that
we use to update Chrome. A much simpler solution for web apps is to do
exactly what AppCache did, create a manifest which lists all the resources,
and let HTTP do the rest: each file can be downloaded and updated
individually, etc.

ig

[1]
http://www.chromium.org/developers/design-documents/software-updates-courgette



> On Thu, Oct 24, 2013 at 11:17 PM, Ilya Grigorik <igrigorik at gmail.com>wrote:
>
>> + 1 to François's comments.
>>
>> You're not saying that gzipping and wise pre-fetching and parallel
>>> download of scripts don't improve page load times. Or are you?
>>>
>>
>> - We already have transfer-encoding in HTTP, and yes, you should
>> definitely use it!
>> - Prefetching is also an important optimization, but in the context of
>> this discussion (bundling), it's an orthogonal concern.
>>
>>
>>> In the equation you paint above something important is missing: the fact
>>> that there's a round-trip delay per request (even with http2.0), and that
>>> the only way to avoid it is to bundle things, as in .zip bundling, to
>>> minimize the (number of requests and thus the) impact of latencies.
>>>
>>
>> With HTTP 1.x (and without sharding) you can fetch up to six resources in
>> parallel. With HTTP 2.0, you can fetch as many resources as you wish in
>> parallel. The only reason bundling exists as an "optimization" is to work
>> around the limit of six parallel requests. The moment you remove that
>> limitation, bundling is unnecessary and only hurts performance.
>>
>>
>>> And there's something else I think .zip bundling can provide that
>>> http2.0 can't: the guarantee that a set of files are cached by the time
>>> your script runs: with such a guarantee you could do synchronous module
>>> require()s, à la node.js.
>>>
>>
>> This is completely orthogonal... if you need to express dependencies
>> between multiple resources, use a loader script, or better.. look into
>> using upcoming promise API's. As I mentioned previously, bundling breaks
>> streaming / incremental execution / prioritization.
>>
>> ig
>>
>>
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>>
>>
>
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