Writing a web server that supports chunked transfers

[Josh]

Hi -

I'm new to Go and trying to write a simple web server that supports
chunked transfers. I started with the sample web server from the http
package documentation, but I can't seem to get the Transfer-Encoding
header set to "chunked" no matter what I try.

Here is the code I have so far:

package main
import (
"http"
"log"
)

func MyServer(writer http.ResponseWriter, req *http.Request) {
writer.SetHeader("Transfer-Encoding", "chunked")
writeCloser := http.NewChunkedWriter(writer)
msg := []byte("Testing\n")
writeCloser.Write(msg)
writeCloser.Close()
}

func main() {
http.HandleFunc("/", MyServer)
error := http.ListenAndServe(":9999", nil)
if error != nil {
log.Exit("ListenAndServe: ", error.String())
}
}

When I hit http://localhost:9999, I see the output I would expect in
the body, but the Transfer-Encoding header is still set to "Identity",
not "chunked".

What's the right way to go about doing this? Thanks in advance for
any help.

[Andrew Gerrand]

I could be wrong, but it looks like setting the Transfer-Encoding
header with SetHeader doesn't update the TransferEncoding element of
the underlying Response struct. This means that when the response is
being finally written, the Transfer-Encoding header is removed and
ignored. This might be an artefact of some refactoring that happened
in the http libraries a few months ago.

Please file an issue at the issue tracker:
http://code.google.com/p/go/issues/entry

Andrew

[Josh]

Thanks for the feedback guys. Much appreciated. I've gone ahead and
filed an issue, per your suggestion Andrew.

I also tried out your suggestion Gary, but so far, no luck.

On Dec 5, 7:34 pm, Andrew Gerrand <a...@golang.org> wrote:
> I could be wrong, but it looks like setting the Transfer-Encoding
> header with SetHeader doesn't update the TransferEncoding element of
> the underlying Response struct. This means that when the response is
> being finally written, the Transfer-Encoding header is removed and
> ignored. This might be an artefact of some refactoring that happened
> in the http libraries a few months ago.
>
> Please file an issue at the issue tracker:
>  http://code.google.com/p/go/issues/entry
>
> Andrew
>

> On 6 December 2010 14:02, Josh <raskcha...@gmail.com> wrote:
>
>
>
> > Hi -
>
> > I'm new to Go and trying to write a simple web server that supports
> > chunked transfers.  I started with the sample web server from the http
> > package documentation, but I can't seem to get the Transfer-Encoding
> > header set to "chunked" no matter what I try.
>
> > Here is the code I have so far:
>
> > package main
> > import (
> >  "http"
> >  "log"
> > )
>
> > func MyServer(writer http.ResponseWriter, req *http.Request) {
> >  writer.SetHeader("Transfer-Encoding", "chunked")
> >  writeCloser := http.NewChunkedWriter(writer)
> >  msg := []byte("Testing\n")
> >  writeCloser.Write(msg)
> >  writeCloser.Close()
> > }
>
> > func main() {
> >  http.HandleFunc("/", MyServer)
> >  error := http.ListenAndServe(":9999", nil)
> >  if error != nil {
> >    log.Exit("ListenAndServe: ", error.String())
> >  }
> > }
>

> > When I hithttp://localhost:9999, I see the output I would expect in

[Josh]

Curious....when I use curl, as you suggest, I also see Transfer-
Encoding set to "chunked". But, when I use the web inspector in
Safari, it shows Identity. It also shows Identity when I use
HTTPClient (http://ditchnet.org/httpclient/). Any idea on why it
would be different?

On Dec 5, 8:48 pm, gary b <gary.b...@gmail.com> wrote:
> The Go http server either sets the response transfer encoding header
> to "chunked" or it does not set the header.  If you are seeing the
> response transfer encoding header set to "identity", then I suspect
> that there's something between your client and the server.
>
> When I dump the headers from your  application using "curl -D -http://localhost:9999/", I see the transfer encoding header set to
> "chunked".
>
> How are you examining the output from the server?