[web-devel] Content-Length on sendFile
feeder.of.the.bears at gmail.com
Tue Jun 14 20:55:26 CEST 2011
On Tue, Jun 14, 2011 at 11:50 AM, Michael Snoyman <michael at snoyman.com>wrote:
> I think the reason we didn't include the header is because, when I
> wrote it, I didn't know of a cross-platform way to get file sizes. Now
> that I know about unix-compat, this seems like a reasonable thing to
> add. Anyone know a reason we *shouldn't* do this?
In Lift, we do not automatically populate the Content-Length for generic
BLOB responses because if the response is streaming, then we have to
strictly evaluate the stream to determine the length. For returning large
items (e.g., a 2 GB AVI), this can cause issues. We break the Response
types into "In Memory" which are strict and we include the Content-Length
header, but for responses that are not strict, it's up to the coder.
My 2 cents.
> On Tue, Jun 14, 2011 at 8:16 PM, Nubis <nubis at woobiz.com.ar> wrote:
> > Hi guys,
> > Just wanted to give you a heads up that yesod's sendFile is not setting
> > Content-Length header, which 'breaks' some proxies and load balancers.
> > our case, amazon elastic load balancer).
> > I don't know if that's by design, I'm not 100% sure but not setting the
> > header would be only useful for 'long pooling' of binary files for doing
> > some sort of hackish http streaming, which I don't think is yesod's
> > anyways :)
> > A workaround is setting the Content-Length header before calling
> sendFile, I
> > guess it may be something easy to add, I was going to propose a patch
> > just wraps the current implementation in a do block that sets the header,
> > but then I noticed a number of optimizations being made that hint there
> > should be a 'better' way.
> > cheers!
> > ----nubis :)
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Lift, the simply functional web framework http://liftweb.net
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