Hi! Is there any calculations available for exi and zlib?
Cheers, <Juha> >-----Original Message----- >From: [EMAIL PROTECTED] >[mailto:[EMAIL PROTECTED] On Behalf Of ext Dave Cridland >Sent: 18 February, 2008 15:17 >To: XMPP Extension Discussion List >Subject: Re: [Standards] Proposed XMPP Extension: Stream >Compression with Efficient XML Interchange > >On Sat Feb 16 10:18:37 2008, Fabio Forno wrote: >> Did some homework about EXI. > >As did I - not that I'm claiming expertise quite yet. Some >random notes follow. > >I basically agree that we don't want to be doing this as >XEP-0138, for a number of reasons, including it being an >additional round-trip, but it works as a way of doing some >experimentation. > >What's currently concerning me is that a single schemaID >option may be present, which indicates the single schema >you've used for encoding. > >Currently, we have no such single schema, and in the absence >of such a schema, my understanding is that the bulk of the >performance of EXI is down to its usage of DEFLATE - thus >somewhat contradicting those people who've been telling me >that DEFLATE is a Bad Thing for mobile devices, but EXI is >fantastic. Ho hum. > >The schemaID is non-restrictive - that is, that use of a >schemaID wouldn't restrict usage of other schemas. So >specifying bling use of EXI is insufficient for our purposes - >we need to define a single schema which represents the overall >schema used for the stream. > >On top of that, the more accurate that schema is, the better >compression will be achieved - out performing DEFLATE by a >reasonable margin. This suggests that the more we put into our >master schema, the better - so we probably want more than one >of them, to allow for different deployment types to handle >their cases optimally. > >So it seems to me that if we were using EXI in XEP-0138, a >single "exi" algorithm isn't sufficient to grant >interoperability. Instead, we need a method for negotiating >schemaIDs, codecs, and the various other random options. In >particular, we probably want the precompression option >available, for the rather odd case of doing DEFLATE in TLS, >but EXI in XEP-0138. > >It occurs to me that for certain schemas particularly heavy in >markup, like SVG whiteboarding, the compression potential is >pretty high, but for quite a few typical uses of XMPP - like >IM itself - the bulk of the compression will be down to >DEFLATE anyway, suggesting that doing EXI in these cases isn't >worthwhile - although I may be wrong here. > >Dave. >-- >Dave Cridland - mailto:[EMAIL PROTECTED] - xmpp:[EMAIL PROTECTED] > - acap://acap.dave.cridland.net/byowner/user/dwd/bookmarks/ > - http://dave.cridland.net/ >Infotrope Polymer - ACAP, IMAP, ESMTP, and Lemonade >
