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From Sorin Manolache <>
Subject Re: Calling another URL from output filter
Date Mon, 05 Mar 2012 09:26:00 GMT
On 2012-03-04 19:19, Swaminathan Bhaskar wrote:
> Hello,
> How can I call another url from an output filter - here is the scenario:
> when a client accesses, this url autheticates the
> user and we dont want the response going back to the client rather call
> another url which will return some data ... we
> want to send the data from the second url and response headers from first
> url merged back to the client. So my thought is to intercept the response
> from the first url in an output ffilter and make a call from the output
> filter to the second url. What function call would allow me to make th call
> to the second url Any help appreciated


We did something similar but we didn't issue the 2nd request from the 
output filter of the first.

The first request was made by the apache subrequest API (the 
ap_sub_req_lookup_uri and ap_run_sub_req functions). The output filter 
ran until it encountered an end-of-stream. It did not make any other 
request. The output filter of the subrequest did not pass any brigade to 
downstream filters. It simply parsed the response, stored relevant data 
in some structure and returned APR_SUCCESS to its upstream filters.

Next, after ap_run_sub_req returned, we invoked the 2nd URL via the 
proxy module. The useful data returned by the 1st URL was taken from the 
structure in which the subrequest stored it.

Calling a 2nd URL from output filters is a bit tricky, as you have 
filter-chains invoked from within a filter-chain, so we preferred to 
call the 2nd URL only after the request to the first completed.


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