Path: utzoo!attcan!uunet!munnari.oz.au!bruce!trlluna!rhea!exner From: exner@rhea.trl.oz (Rolf Exner - css) Newsgroups: comp.protocols.iso Subject: Re: X500: Does alias have to point to an existing entry? Message-ID: <742@trlluna.trl.oz> Date: 2 Oct 89 04:17:08 GMT References: <8909142001.AA29457@emu.ncsl.nist.gov> Sender: root@trlluna.trl.oz Lines: 30 (My mail access has been down for a while) From article <8909142001.AA29457@emu.ncsl.nist.gov>, by colella@EMU.NCSL.NIST.GOV (Richard Colella): > > Yes, you can create an alias that points to a non-existent entry. > The decision to let this happen was made a couple of years ago. > The standards folks decided that the tradeoff between the complexity > and cost of guaranteeing aliases appeared to outweigh the necessity > of having this feature. Supporting guaranteed aliases is complex and operationally costly when the alias points to an entry in a remote DSA. (Note that current extensions work in CCITT/ISO on X.500 is again looking at supporting such aliases as a second kind of alias) Yet this does not mean that aliases that point to non-existent objects have to be retained by a DSA. Directory management actions, outside the scope of the standards, may delete such dangling aliases whenever they are detected - e.g on receipt of an aliasProblem NameError. X.500 makes no guarantee that an entry created one day (and not removed via RemoveEntry) will be there the next. A DSA may also elect to keep its own house on order and prevent the creation of alias entries that it *knows* point to a non-existent entry (X.511, 11.1.2.2 notwithstanding). It can do this simply by returing an unwillingToPerform ServiceError on the basis that it violates local administrative policy. Rolf Exner Telecom Australia Research Laboratories.