Article View: comp.protocols.iso.dev-environ
Article #546OPTIONAL SEQUENCES and pepy
From: John Tebbutt
Date: Wed, 27 Mar 1991 17:24
Date: Wed, 27 Mar 1991 17:24
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2298 bytes
This is a reposting of something I put out a week ago which was immediately
met with a deafening silence! Since it generated so much interest the first
time around, it occurred to me that you all might like to see it again, so
here it is ;^)
PS I figure the reason I got so few responses was either that I was way wide
of the mark and had missed some fundamental truth or that I had inadvertantly
discovered a genuine problem with pepy which has had all the ISODE people
scratching their heads ever since. My money is on the former, but I would
appreciate any feedback whatsoever - even RTFMs!
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I have a problem relating to how an application can discern between an
OPTIONAL SEQUENCE which is present but empty, and one which is absent,
based on the pepy decoder generated local C structure.
For example, if I have an ASN.1 definition:
DistributedOperationsArgument ::=
SET {
originator[0]
DistinguishedName
OPTIONAL,
targetObject[1]
DistinguishedName
OPTIONAL,
...
}
...where DistinguishedName ::= SEQUENCE OF SomethingOrOther,
the corresponding pepy generated struct looks like this:
struct DistributedOperationsArgument {
struct DistinguishedName *originator;
struct DistinguishedName *targetObject;
...
};
Now, if originator == (struct DistinguishedName *)NULL, does that mean
(a) that originator was not present in the encoding, (b) that
originator was present but empty, or (c) either/both? In the case of
(a) or (b), what value of originator would indicate the converse?
Many thanks in advance for any insights.
JT
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!usc!apple!agate!ucbvax!RHINO.NCSL.NIST.GOV!tebbutt From: tebbutt@RHINO.NCSL.NIST.GOV (John Tebbutt) Newsgroups: comp.protocols.iso.dev-environ Subject: OPTIONAL SEQUENCES and pepy Message-ID: <9103271724.AA02050@rhino.ncsl.nist.gov> Date: 27 Mar 91 17:24:13 GMT Sender: daemon@ucbvax.BERKELEY.EDU Distribution: inet Organization: National Institute of Standards and Technology (NIST) Lines: 56