[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: XML Binary and Compression
Hmm, I'm sorry you don't think schema-based encoding is fair. I find it odd that you regard schema-based (encoding) compression as lossy. This term is normally associated with a permanent loss of information. Neither ASN.1 or MPEG-7 result in the loss of XML content (the original content did not of course contain the XML schema). The deployment of the schema upon which encoding/decoding is based in a management issue. There is no need to transmit it as part of the encoded content. - Dan > -----Original Message----- > From: Elliotte Rusty Harold [mailto:elharo@m...] > Sent: Tuesday, March 11, 2003 10:01 AM > To: winkowski@m...; msc@m...; xml-dev@l... > Cc: winkowski@m...; msc@m... > Subject: RE: XML Binary and Compression > > > At 11:54 PM -0500 3/10/03, winkowski@m... wrote: > > >On reflection, I don't think that the conclusions reached > are all that > >surprising. Redundancy based compression achieves better > results as the file > >size, and consequently the amount of redundancy, increases. > CODECS that take > >advantage of schema knowledge achieve efficient localized > encodings and also > >need not transmit metadata since this information can be > derived at decoding > >time. > > I may have missed something in your paper then, because I didn't > realize you were doing this. If you're assuming that the same schema > is available for both compression and decompression, then you're > doing a lossy compression. The conmpressed forms of your documents > have less information in them than the uncompressed forms. I don't > consider that to be a fair or useful comparison with raw XML with > metadata present. > > Then again, maybe that's not what you meant? If you're somehow > embedding a schema in the document you transmit, then it's really > just another way of compressing losslessly and that's OK, though In > would still require that the schema used for compression be derived > from the instance documents rather than applied pre facto under the > assumption of document validity. Hmmm, that's not quite right. What I > really mean is that given a certain schema it must be possible to > losslessly encode both valid and invalid documents. > -- > > +-----------------------+------------------------+-------------------+ > | Elliotte Rusty Harold | elharo@m... | Writer/Programmer | > +-----------------------+------------------------+-------------------+ > | Processing XML with Java (Addison-Wesley, 2002) | > | http://www.cafeconleche.org/books/xmljava | > | http://www.amazon.com/exec/obidos/ISBN%3D0201771861/cafeaulaitA | > +----------------------------------+---------------------------------+ > | Read Cafe au Lait for Java News: http://www.cafeaulait.org/ | > | Read Cafe con Leche for XML News: http://www.cafeconleche.org/ | > +----------------------------------+---------------------------------+ >
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