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https://issues.apache.org/jira/browse/NUTCH-2707?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16811949#comment-16811949
 ] 

Sebastian Nagel commented on NUTCH-2707:
----------------------------------------

Turns out that there are few more servers which does not conform to the 
standard and answer on a request with {{Accept-Encoding: gzip}} with something 
different than {{Content-Encoding: gzip}} or {{Content-Encoding: identity}}. We 
should at least try to handle most of these cases. Further examples:

- same as the initial problem:
{noformat}
% nutch parsechecker -Dplugin.includes='protocol-okhttp|parse-tika' 
-Dstore.http.headers=true -Dstore.http.request=true 
https://saudibusiness.directory/%D8%A7%D8%AB%D8%A7%D8%AB%D9%83%D9%88%D9%85-5741.html
...
contentType: application/gzip
...
Content Metadata: ... _request_=GET 
/%D8%A7%D8%AB%D8%A7%D8%AB%D9%83%D9%88%D9%85-5741.html HTTP/1.1
...
Accept-Encoding: gzip

 _response.headers_=HTTP/1.1 200 OK
Date: Sun, 07 Apr 2019 14:19:15 GMT
Server: Apache
X-Powered-By: PHP/5.6.30
Content-Encoding: zlib,gzip,deflate
...
{noformat}

- response uses "deflate" although "gzip" is requested:
{noformat}
% bin/nutch parsechecker -Dplugin.includes='protocol-okhttp|parse-tika' 
-Dstore.http.headers=true -Dstore.http.request=true 
https://de.wantedly.com/all/japan/designer/businessmodel
...
contentType: application/zlib
...
Content Metadata: ... _request_=GET /all/japan/designer/businessmodel HTTP/1.1
...
Accept-Encoding: gzip

... _response.headers_=HTTP/1.1 200 OK
Date: Fri, 05 Apr 2019 15:56:01 GMT
...
Server: nginx
...
Content-Encoding: deflate
...
{noformat}


> protocol-okhttp fails to decompress content if Content-Encoding header is 
> wrong
> -------------------------------------------------------------------------------
>
>                 Key: NUTCH-2707
>                 URL: https://issues.apache.org/jira/browse/NUTCH-2707
>             Project: Nutch
>          Issue Type: Bug
>          Components: plugin, protocol
>    Affects Versions: 1.15
>            Reporter: Sebastian Nagel
>            Priority: Minor
>             Fix For: 1.16
>
>
> The plugin protocol-okhttp does not decompress the returned gzipped content 
> for some rare pages.  Looks like that happens because the response HTTP 
> header does not specify {{Content-Type: gzip}} but {{zlib,gzip,deflate}}.
> {noformat}
> % bin/nutch parsechecker -Dplugin.includes='protocol-okhttp|parse-tika' \
>       -Dstore.http.headers=true -Dstore.http.request=true \
>       http://24310.gr/afroditi-42426.html
> fetching: http://24310.gr/afroditi-42426.html 
> ...
> contentType: application/gzip
> ...
> Content Metadata: Transfer-Encoding=chunked ... 
> Content-Encoding=zlib,gzip,deflate ... _request_=GET /afroditi-42426.html 
> HTTP/1.1
> ...
> Accept-Encoding: gzip
>  _response.headers_=HTTP/1.1 200 OK
> ...
> Content-Encoding: zlib,gzip,deflate
> ...
> Transfer-Encoding: chunked
> Connection: keep-alive
> {noformat}
> The plugin protocol-http requests {{Accept-Encoding: x-gzip, gzip, deflate}} 
> and gets the correct response header:
> {noformat}
> % bin/nutch parsechecker -Dplugin.includes='protocol-http|parse-tika' \
>        -Dstore.http.headers=true -Dstore.http.request=true 
> http://24310.gr/afroditi-42426.html
> ...
> contentType: application/xhtml+xml
> ...
> Content Metadata: ... Content-Encoding=gzip ... _request_=GET 
> /afroditi-42426.html HTTP/1.1
> Host: 24310.gr
> Accept-Encoding: x-gzip, gzip, deflate
> ...
> {noformat}
> Similar for Firefox which sends {{Accept-Encoding: gzip, deflate}}.
> I will report the issue to upstream okhttp. But it would be also possible to 
> handle the content encoding in the protocol implementation: if the 
> Accept-Encoding header is set, the okhttp library will not decompress the 
> content and expects that it's handled in the calling code.



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