There is nothing wrong with the ASN.1 you are producing, and, indeed, if you are wanting concatenation of APDUs this is probably the best way to do it.

I think your other questions are more tool issues, but I am copying this to [EMAIL PROTECTED], where I am sure someon will give you a better answer than mine!

John L


[EMAIL PROTECTED] wrote:




Hello. I’ve talked to you before about ASN.1 issues and you were very
helpful.

I’m having a bit of a dilemma with an ASN.1 decision.  We simply want to
“chain” multiple protocol data units in a single data frame. We do specify
that PER be used to create the transfer syntax.
What we really need is some control fields within the data  used by a
parsing mechanism to sort out the start of each PDU and the end PDU in the
chain.

It was suggested that an Apdu-Concat as defined below.
-- -----------
Apdu ::=    CHOICE
            { action.request  [0]Action-Request
            , action.response [1]Action-Response
            , get.request           [2]Get-Request
            , get.response          [3]Get-Response
            -- more choices follow
            }
Apdu-Concat ::= SEQUENCE (1..4)OF Apdu –- (4 as example)
-- -------------
Knowing a bit of how PER works, this would form a bit string with:    (no.
in sequence)(1st choice){structure}(2nd choice){structure)(etc.)
all packed up but parseable – if you know how PER works.
Is it correct to do such a thing?
I guess the basic issues are:
Should control structure be visible in the ASN.1 even though there is an
underlying control mechanism inserted by the encoder?
If you rely on the encoders control structure, does a translator from ASN.1
to “C” structure, for instance, make the control visible — (can’t seem to
find much on this).
Is there a reference to discussion of such matters that you suggest.
(I have done some web searching but when you consider that my search engine
returns 89,100 hits on the phrase “information overload” you begin to
understand how just a hint is greatly appreciated.)

Regards, KenCook
[EMAIL PROTECTED]
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   Prof John Larmouth
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