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From: Sven Zethelius <svenz@expedia.com>
To: "httpclient-users@hc.apache.org" <httpclient-users@hc.apache.org>
Subject: httpasyncclient BasicAsyncRequestProducer prevents
 HttpRequestInterceptor from replacing HttpEntity of the request
Thread-Topic: httpasyncclient BasicAsyncRequestProducer prevents
 HttpRequestInterceptor from replacing HttpEntity of the request
Thread-Index: AQHRmxXJQSUJRmklGkyfzYMEzsXbLQ==
Date: Wed, 20 Apr 2016 15:03:24 +0000
Message-ID: <D33CE848.3B59F%svenz@expedia.com>
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I am trying to use a HttpRequestInterceptor to adapt a request sent to a or=
g.apache.http.impl.nio.client.CloseableHttpAsyncClient.  I want to do reque=
st body compression (e.g. Content-Encoding: gzip for HttpRequest, not Accep=
t-Encoding) following the example here: https://hc.apache.org/httpcomponent=
s-client-4.2.x/httpclient/examples/org/apache/http/examples/client/ClientGZ=
ipContentCompression.java .  The example is for response compression, but i=
t looked like I could do the same thing to do request compression, and I ne=
ed to handle response compression too.

After much debugging I realized the HttpRequestInterceptor would allow me t=
o change the headers, but not the HttpEntity that was sent.  The entity sen=
t is always the original one passed into the AsyncHttpClient.  On the serve=
r, I see the "Content-Type: gzip" and a "Content-Length" header for the gzi=
pped length (Content-Length was set by the internal interceptors), but the =
bytes sent are the original values from the NByteArrayEntity, which leads t=
o exceptions since Content-Length doesn't match actual length after GZIP.

I tracked it down to the constructor for org.apache.http.nio.protocol.Basic=
AsyncRequestProducer.  The BasicAsyncRequestProducer is created before the =
interceptors run.  In the producer constructor, the entity from the request=
 is stored as the producer.  This occurs before the HttpRequestInterceptor =
has a chance to manipulate the entity.

My idea for a patch would be to delay load the producer field until after t=
he interceptors have run.  Looking at the class, that would have to be in p=
roduceContent, before it checks for producer=3D=3Dnull. Since the request i=
s also a member, this would allow the producer to be set based on what's in=
 the request when we actually produce the output, rather than what was in i=
t when the whole processing chain started.

Is patching the BasicAsyncRequestProducer the only way to do this or is the=
re a simpler way that I am missing?


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