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From Filip Hanik - Dev Lists <>
Subject Re: Obtain a SocketChannel instead of OutputStream ?
Date Tue, 05 Feb 2008 16:11:01 GMT
John Caron wrote:
> My application is a scientific data server that transfers large 
> amounts of binary data. I am looking to make it as fast as possible 
> and have been experimenting with the NIO FileChannel.transferTo() 
> method. This appears to be much faster (3-10X) than using an 
> OutputStream, under some circumstances. So I am trying to see if I can 
> use this from within Tomcat.
> So the question is whether there is a way to obtain a SocketChannel 
> for the connection? The standard interface only allows to get an 
> OutputStream. While Channels.newChannel(OutputStream out) gives a 
> WriteableByteChannel, the transferTo() method does not work on it, 
> apparently one needs to get the SocketChannel at a deeper level.
> Has anyone else tried this? Any ideas would be much appreciated.
we haven't exposed the API at this level, since the data you write to 
the network, must go through several filters.
you can still take advantage of the direct transfers by using Tomcat's 
built in send file technique.

A user previously wrote:

 Any servlet can instruct Tomcat to perform a sendfile call by setting 
the appropriate response attributes. When using sendfile...
    * org.apache.tomcat.sendfile.filename: Canonical filename of the 
file which will be sent as a String
    * org.apache.tomcat.sendfile.start: Start offset as a Long
    * org.apache.tomcat.sendfile.end: End offset as a Long

So add these attributes into the request, (see for 
an example), and if you are using the APR or the NIO connector in 
Tomcat, tomcat will transfer them directly


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