Hello all, I'm studying the Yesod book by Michael Snoyman and I'm slowly coming to grips with Haskell for the web. My current goal is to write an http(s) proxy that does filtering and caching. I've found a nice example by Snoyman on github: https://gist.github.com/snoyberg/8779671 This code does not compile with wai >= 3 because that does not have responseSourceBracket any more. What is the best way to replace it? --- Wai.responseSourceBracket (HCl.responseOpen req2 man) (HCl.responseClose) $ \res -> do let body = mapOutput (Chunk . fromByteString) $ HCC.bodyReaderSource $ HCl.responseBody res headers = filter safeResHeader $ HCl.responseHeaders res return (HCl.responseStatus res, headers, body) ---- Best regards, Jos van den Oever
I've updated that Gist to be compatible with WAI 3.0. The basic changes I
made were:
1. Change the way Warp settings are applied (no longer use record syntax,
but explicit set* functions).
2. conduit is no longer the standard streaming interface for WAI, so
imported Network.Wai.Conduit and used helper functions from there.
3. The specific question you asked about: the semantics for how to do
resource allocation in an application have changed. There were some holes
in the previous approach that allowed async exceptions to leak in at the
wrong time. Instead, WAI 3.0 uses a similar interface to most resource
allocation functions in Haskell (like bracket or withFile). Specifically,
this looks like:
HCl.withResponse req2 man $ \res -> do
let body = mapOutput (Chunk . fromByteString) $
HCC.bodyReaderSource $ HCl.responseBody res
headers = filter safeResHeader $ HCl.responseHeaders res
respond $ responseSource (HCl.responseStatus res) headers body
Some notes on this are available at:
*
http://hackage.haskell.org/package/wai-3.0.2.3/docs/Network-Wai.html#t:Appli...
*
http://www.yesodweb.com/book/web-application-interface#web-application-inter...
On Fri, Mar 6, 2015 at 10:58 AM Jos van den Oever
I'm studying the Yesod book by Michael Snoyman and I'm slowly coming to grips with Haskell for the web.
My current goal is to write an http(s) proxy that does filtering and caching. I've found a nice example by Snoyman on github: https://gist.github.com/snoyberg/8779671
This code does not compile with wai >= 3 because that does not have responseSourceBracket any more. What is the best way to replace it?
--- Wai.responseSourceBracket (HCl.responseOpen req2 man) (HCl.responseClose) $ \res -> do let body = mapOutput (Chunk . fromByteString) $ HCC.bodyReaderSource $ HCl.responseBody res headers = filter safeResHeader $ HCl.responseHeaders res return (HCl.responseStatus res, headers, body) ----
Best regards, Jos van den Oever _______________________________________________ web-devel mailing list web-devel@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/web-devel
On Sunday 08 March 2015 07:28:30 Michael Snoyman wrote:
I've updated that Gist to be compatible with WAI 3.0.
Thank you very much. I've been studying that code and have successfully made a proxy on top of Warp and am now adding a user interface on top with Yesod. I've made a tweak to the code a bit. In the gist you throw out most of the request and response headers. I've found that it's enough to only throw away the content-encoding and content-length headers: headers = filter removeEncodingHeaders $ HCl.responseHeaders res respond $ WC.responseSource (HCl.responseStatus res) headers body where -- remove encoding information removeEncodingHeaders (k, _) = k `notElem` [ "content-encoding", "content- length" ] Cheers, Jos
participants (2)
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Jos van den Oever -
Michael Snoyman