[web-devel] proxy with wai

[Michael Snoyman]

Can you provide:

* A complete file
* The error messages you're getting

On Thu, Mar 26, 2015 at 9:10 PM Jos van den Oever <jos at vandenoever.info>
wrote:

> On Tuesday 24 March 2015 07:01:39 Michael Snoyman wrote:
> > On Sun, Mar 22, 2015 at 10:01 AM Jos van den Oever <jos at vandenoever.info
> >
> >
> > wrote:
> > > On Sunday 08 March 2015 07:28:30 you wrote:
> > > > 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
> > >
> > > I'd like my proxy to be a caching proxy so each request shoule be
> saved to
> > > a
> > > file. I've tried adding an additional sink, (sinkFile) or conduit
> > > (conduitFie)
> > > to the HCC.bodyReaderSource, but cannot it right. What would be a good
> way
> > > to
> > > do this?
> >
> > What have you tried so far?
>
> This is the code I have so far. I've annotated with a types. This code
> gives a
> compile error because of the line 'source2 = bodySource C.=$= fileSaver'.
> The
> MonadResource is not arising from the use in fileSaver. Somehow, I've to
> get
> runResourceT in there.
>
> ===
>     HCl.withResponse req2 man $ \res -> do
>         --saver <- CB.conduitFile "/tmp/out"
>
>         let path = "/tmp/out" :: FilePath
>             fileSaver :: MonadResource m => C.Conduit S8.ByteString m
> S8.ByteString
>             fileSaver = CB.conduitFile path
>             bodyReader :: HCl.BodyReader
>             bodyReader = HCl.responseBody res
>             bodySource :: MonadIO m => C.ConduitM () S8.ByteString m ()
>             bodySource = HCC.bodyReaderSource bodyReader
>             source2 = bodySource C.=$= fileSaver
>             chunk :: S8.ByteString -> C.Flush Builder
>             chunk = C.Chunk . fromByteString
>             body :: C.ConduitM () (C.Flush Builder) IO()
>             body = C.mapOutput chunk source2
>             headers = filter removeEncodingHeaders $ HCl.responseHeaders
> res
>
>         time <- getPOSIXTime
>         runSqlPool (insert_ $ Response (round time) reqid Nothing) pool
>         respond $ WC.responseSource (HCl.responseStatus res) headers body
> ===
>
> Cheers,
> Jos
>
>
>
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