Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!orion.oac.uci.edu!ucivax!gateway From: enag@ifi.uio.no Newsgroups: comp.protocols.iso.x400 Subject: Re: DATA Compression and X400 standards Message-ID: Date: 30 Oct 90 19:21:36 GMT References: <531*Eppenberger@verw.switch.ch> Organization: Naggum Software, Oslo, Norway Lines: 31 Approved: usenet@ICS.UCI.EDU In-Reply-To: Eppenberger@verw.switch.ch's message of 29 Oct 90 08:55:15 GMT x-attn: jns ReSent-To: mhsnews@ICS.UCI.EDU In article <531*Eppenberger@verw.switch.ch>, Urs Eppenberger writes: From my point of view data compression should not be handled within the framework of X.400. This is purely a matter of the lower layers. We have already a mess with all the body parts, I can't see any reason to add compressed ones. If some X.400 implementation store messages in a compressed format on disk, I do not care and see also no need for standardisation. Perhaps this view is too easy? Aren't all those layers supposed to make things easier? Seriously, does anybody know of attempts to standardize compression schemes so they can be negotiated by the (re)presentation entities at connection establishment time? CCITT has recommended compression schemes at the data link layer for low-speed PSTN connections, i.e. in the V-series (V.42, I believe). I don't know whether it is possible to negotiate this at a higher level, and whether it is possible to propagate PDU boundaries so that the data link layer algorithm does not reduce the average transmission speed in the presence of quick turnarounds, small windows, etc. Just curious. -- [Erik Naggum] Naggum Software; Gaustadalleen 21; 0371 OSLO; NORWAY I disclaim, , therefore I post. +47-295-8622, +47-256-7822, (fax) +47-260-4427 --