Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!CISCO.COM!cire From: cire@CISCO.COM (cire|eric) Newsgroups: comp.protocols.iso Subject: Re: Null Protocol Layers Question Message-ID: <8907022203.AA17701@ucbvax.Berkeley.EDU> Date: 2 Jul 89 20:24:50 GMT References: <29-Jun-89.115441@192.41.214.2> Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 62 >> >From iso-RELAY@SRI-NIC.ARPA Sat Jul 1 01:33:16 1989 >> Date: 29 Jun 89 15:40:03 GMT >> From: intercon!amanda%intercon.uu.net@uunet.uu.net (Amanda Walker) >> Subject: Re: Null Protocol Layers Question >> References: <36800002@m.cs.uiuc.edu> >> Sender: iso-relay@sri-nic.arpa >> To: iso@sri-nic.arpa >> >> In article <36800002@m.cs.uiuc.edu>, zweig@m.cs.uiuc.edu writes: >> > [...] >> > Furthermore, this nonsense about "having to do the encoding at runtime" is >> > laughable. >> > [...] >> > -Johnny The-OSI-Reference-Model-has-nothing-to-do-with-Implementation >> > (#include ) >> >> I agree completely. ASN.1/BER are *representations*, not algorithms. Once >> "the bits are on the wire," so to speak, how they got there is immaterial, >> as is what the receiving process does with them. >> . . . >> -- >> Amanda Walker >> InterCon Systems Corporation >> -- >> amanda@intercon.uu.net | ...!uunet!intercon!amanda This is like saying that Theory has nothing to do with Application. While in many cases it is certainly true that a Model has nothing to do with Implementation it is not always the case. If the goal is to build a model that maps to many different instantiations then a completely independent model is desireable. In that case it is indeed true that the model doesn't have that much to do with an implementation. So XDR or ASN.1 are representations. Big deal. Given any representation there are many implementations some better than others. Given a particular machine and a particular representation there is at least one optimal implementation. Optimal when performance is considered. Performance is a big deal that's what's driving all of this conversation. Given different representations and their mappings to a given machine will directly impact the implementation and the resultant performance. In other words, the Model and the Representation directly impact the implementation and the resultant performance. -c cire|eric Eric B. Decker Token Ring Development cisco Systems - engineering Menlo Park, California email: cire@cisco.com uSnail: 1360 Willow Rd., Menlo Park, CA 94025 Phone : (415) 326-1941 I speak for myself here.