Non-blocking file upload

[Frazer Irving <fr...@bbc.co.uk>]

Hi,

I have a requirement to upload a file, and to have the transfer of data 
be interrupted in the event of the server responding with an error. My 
code looks like:

             MimetypesFileTypeMap mime = new MimetypesFileTypeMap();
             request = new PostMethod(url);

             MonitoredRequestEntity ent = new MonitoredRequestEntity(
                     stream, file.length(), mime.getContentType(file), 
listener);
             request.setRequestEntity(ent);
             int status = 0;
             try {
                 status = httpClient.executeMethod(request);
             } catch (Exception e) {
                 if (!request.isAborted()) {
                     logger.error("http post failed for job {}", jobId, e);
                     listener.setStatus(new UploadStatus().setFailed());
                 }
                 return;
             }
             if (status != HttpStatus.SC_ACCEPTED && status != 
HttpStatus.SC_OK) {
                 throw new 
MuseException(request.getStatusLine().toString());
             }

It seems that the call to executeMethod is blocking until the entire 
body of the RequestEntity has been written to the server before 
processing the response. Is there a way to have the response processed 
earlier? The files in question are very large and I would like to avoid 
the transfer if possible.

I am using MultiThreadedHttpConnectionManager to manage connections if 
that affects things.

f

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Re: Non-blocking file upload

[Oleg Kalnichevski <ol...@apache.org>]

On Wed, 2011-02-16 at 11:05 +0000, Frazer Irving wrote:
> Hi,
> 

...

> It seems that the call to executeMethod is blocking until the entire 
> body of the RequestEntity has been written to the server before 
> processing the response.

Yes, this is indeed the case due to the limitations of the blocking I/O
model in Java (a thread execution while blocked in an I/O operation is
unable to react to other events).

>  Is there a way to have the response processed 
> earlier? The files in question are very large and I would like to avoid 
> the transfer if possible.
> 

You can try out the asynchronous version of HttpClient, based on NIO,
which does not have such limitation.

http://hc.apache.org/httpcomponents-asyncclient-dev/index.html

Please note, though, HttpAsyncClient is still an early alpha and is
likely to have defects.

Your application will need to implement a custom ProducingNHttpEntity or
HttpAsyncRequestProducer to able to upload data in a non-blocking
manner.

Hope this helps

Oleg 


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