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From Florian Müller <f...@apache.org>
Subject Re: Odd behavior when Android OpenCMIS Client reuses a connection that server tried to close
Date Fri, 13 Jun 2014 20:42:02 GMT
Thanks for the update. Which Android version are you using?
If that solves the problem, we might also be defensive in OpenCMIS and
enable the stale connection check by default.

- Florian


> Hi Florian,
> 
> Just for the record, I wanted to let you know how we resolved the problem with the Android
OpenCMIS Client reusing a stale connection.  We created a custom HttpInvoker that uses android.net.http.AndroidHttpClient
under the hood.  We enabled the "stale checking" connection setting via:
> 
> 	HttpConnectionParams.setStaleCheckingEnabled(params, true);
> 
> This resolved the problem.  The API for this setting says:
> 
> 	This setting defines whether stale connection check is to be used. Disabling stale connection
check may result in slight performance improvement at the risk of getting an I/O error when
executing a request over a connection that has been closed at the server side.
> 
> ... Brian ...
> Xerox Corporation
> Palo Alto, California
> 
> -----Original Message-----
> From: Inouye, Brian 
> Sent: Thursday, June 12, 2014 9:52 AM
> To: 'Florian Müller'; dev@chemistry.apache.org
> Cc: Vitaliy Khudenko
> Subject: RE: Odd behavior when Android OpenCMIS Client reuses a connection that server
tried to close
> 
> Hi Florian,
> 
> Thank you very much for the advice!  We will consult with Android developer support on
how we can resolve this issue.
> 
> I know in one case we are definitely using a proxy server.  I'll see if we can try without
a proxy server.
> 
> ... Brian ...
> 
> -----Original Message-----
> From: Florian Müller [mailto:fmui@apache.org]
> Sent: Thursday, June 12, 2014 1:35 AM
> To: dev@chemistry.apache.org
> Cc: Inouye, Brian; Vitaliy Khudenko
> Subject: Re: Odd behavior when Android OpenCMIS Client reuses a connection that server
tried to close
> 
>  Hi Brian,
> 
>  OpenCMIS uses the Android HTTP client library and doesn't control the  TCP connections
directly. What you described happens a level below  OpenCMIS.
>  The Android HTTP client has known issues and those issues vary with the  Android version.
To find a solution to this specific problem, please  refer to the Android documentation.
>  There seems to be an issue with HTTP POST (-> createDocument)  somewhere. Are you
using a proxy server? If so, can you retry without  it?
> 
>  There are actually two HTTP client libraries in Android. OpenCMIS uses  by default the
library recommended for Gingerbread and better.
>  You can switch to the older library by setting the session parameter  HTTP_INVOKER_CLASS
to  "org.apache.chemistry.opencmis.client.bindings.spi.http.ApacheClientHttpInvoker".
>  That may solve this issue ... and create others.
> 
> 
>  - Florian
> 
> 
>> In our Android Client, using OpenCMIS 0.10.0 and AtomPub binding, we 
>> see OpenCMIS attempt to reuse a TCP connection that the server has 
>> tried to close.  In response to the Client trying to reuse a 
>> connection that it tried to close, the server correctly replies with a 
>> TCP RST.  We then see the Android Client respond in different ways 
>> depending on what type of request it was attempting to send on the TCP 
>> connection.
>>
>> Case 1: If the Client was trying to do a getChildren, OpenCMIS closes 
>> the connection that the server was trying to close, opens a new 
>> connection and uses that connection for the GetChildren request.  The 
>> request succeeds and everyone is happy.
>>
>> Case 2: If the Client was trying to do a createDocument, OpenCMIS does 
>> NOT close the connection that the server was trying to close.
>> It
>> opens a new connection, but then unexpectedly closes it immediately 
>> after opening it.  Is it confused and closing the wrong connection?
>> At this point, there's no connection available for it to use.
>> Eventually, OpenCMIS throws a "CmisConstraintException: Conflict".
>> The request fails and nobody is happy.
>>
>> I have Wireshark captures that clearly show the above behaviors which 
>> I can make available.
>>
>> Is this a known issue?  I didn't see anything in Jira that resembles 
>> it.  Please let me know how I should proceed in getting this resolved.
>> Thanks!
>>
>> ... Brian ...
>> Xerox Corporation
>> Palo Alto, California
> 


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