peterco@microsoft.UUCP (Peter COOK) (12/14/90)
Can anyone point me at the relevant X.200 section where I can find out what the format of a presentation address is. X.500 defines it as: PresentationAddress ::= SEQUENCE pSelector [0] OCTET STRING OPTIONAL, sSelector [1] OCTET STRING OPTIONAL, tSelector [2] OCTET STRING OPTIONAL, nAddresses [3] SET SIZE(1..MAX) OF OCTET STRING It is supposed to specify "a presentation address associated with an object representing an OSI application entity". What I would like to understand is, are there any standard representations for a pSelector, sSelector, tSelector, or nAddress? OCTET STRING seems to be a bit too ambiguious to be meaningful. Do I just throw anything in these things or are there de-facto standard representations? What is "MAX" here? Thanks in advance, Peter Cook ..uw-beaver!microsoft!peterco
pww@bnr.ca (Peter Whittaker) (12/15/90)
In article <59827@microsoft.UUCP> peterco@microsoft.UUCP (Peter COOK) writes: >Can anyone point me at the relevant X.200 section where I can find >out what the format of a presentation address is. X.500 defines it >as: > > PresentationAddress ::= SEQUENCE > pSelector [0] OCTET STRING OPTIONAL, > sSelector [1] OCTET STRING OPTIONAL, > tSelector [2] OCTET STRING OPTIONAL, > nAddresses [3] SET SIZE(1..MAX) OF OCTET STRING > >It is supposed to specify "a presentation address associated with an object >representing an OSI application entity". What I would like to understand is, >are there any standard representations for a pSelector, sSelector, tSelector, >or nAddress? OCTET STRING seems to be a bit too ambiguious to be meaningful. >Do I just throw anything in these things or are there de-facto standard >representations? What is "MAX" here? > >Thanks in advance, >Peter Cook ..uw-beaver!microsoft!peterco This response has two parts: a quick answer, and a longer pointer to a possible problem with the Blue Books (as if there weren't enough). Part 1: M.T. Rose's "Open Book" makes an important reference on page 340 (sec. 9.1.1): the selectors are only meaningful at particular network addresses. In other words, what you do with them is your business, you just advertise them (i.e. in the directory). Applications wishing to use a particular service of yours look that service up by name, then send the appropriate selectors to you when they attempt to establish a connection. Network addresses are defined in ISO 8348/AD.2, or X.213 (See X.213 A.8). In particular, see A.8.4, where MAX is given as 20 ("max length of an NSAP address in its preferred binary encoding is 20 octets"). Part 2: I think you have found a hole in the Blue Books. According to mine, presentation address is defined in ISO 7498-3. See X.216 sec. 3.3, or X.226, sec. 3.3. ISO 7498-3 is not listed in the CCITT/ISO cross-references found at the beginning of each Blue Book in the X.2xx, X.4xx, and X.5xx series. According to an article in ACM Computer Communications Review, dated July 1990, (v. 20 #3), ISO 7498-3 is part of the X.200 recommendation. According to this article, X.200 comprises the following: ISO 7498-1 basic reference model, published 10-15-84 ISO 7498-2 sec. architecture, not yet published ISO 7498-3 naming and addressing, published 03-01-89 ISO 7498-4 management framework, published 11-15-89 and the following addenda, corrigenda, etc.... :-> 7498-1/Add. 1 connectionless data transmission published 7-15-87 7498-1/PDAD2 Multipeer data transmission not yet published 7498-1/Cor. 1 Technical corrigendum 1 published 12-15-88 NOTE: things may have changed (:->): the PDAD and 7498-2 may have been published, and (I can never remember this part) ISO (or CCITT) has changed their jargon recently; I'm not sure whether PDAD and corrigendum are the correct terms. Best of Luck. Anyone know anymore? Peter "I'm only six months out of date? Wow!" Whittaker -- Peter Whittaker [~~~~~~~~~~~~~~~~~~~~~~~~~~] Open Systems Integration pww@bnr.ca [ ] Bell Northern Research Ph: +1 613 765 2064 [ ] P.O. Box 3511, Station C FAX:+1 613 763 3283 [__________________________] Ottawa, Ontario, K1Y 4H7