Exposing LZ77 sliding window size in the java.util.zip.[Inflator|Defaltor] API

Xueming Shen xueming.shen at oracle.com
Tue Aug 26 17:12:01 UTC 2014

Hi Mark,

It sounds like a reasonable requirement. I have filed the rfe at


Let's consider to add a pair of constructors in In/Deflator in jdk9.


On 08/26/2014 01:45 AM, Mark Thomas wrote:
> Hi,
> I'm currently working on the implementation of the WebSocket
> permessage-deflate extension for Apache Tomcat. I am using the JRE
> provided classes java.util.zip.[Inflator|Defaltor] to do the compression
> and decompression.
> I have a working implementation but there is one feature I can't
> implement because the necessary API isn't available.
> The WebSocket permessage-deflate specification [1] allows both the
> client and server to specify a number between 8 to 15 inclusive
> indicating the base-2 logarithm of the LZ77 sliding window size. The
> purpose of this feature is to enable both the client and the server to
> limit the size of the buffer they need to maintain to reduce their
> memory footprint per connection.
> Would it be possible for the java.util.zip.Inflator and
> java.util.zip.Defaltor API to be extended to expose the LZ77 window
> size? My suggestion would be an additional constructor for each class
> that took and additional int parameter for window size but I'd be happy
> with any API that provided control of the window size.
> Cheers,
> Mark
> [1] http://tools.ietf.org/html/draft-ietf-hybi-permessage-compression-18

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