[Css-csts] Issues regarding procedure-instance-identifier

[Yves.Doat at esa.int]

Dear John,

Using your mail, I raised the RID: NASA-JVP-75 with the following answers:

A. I accept your text. However considering that I find the "null value" 
statement quite clear and that it is also used elsewhere I replaced the 
bullet 'd' with "for prime procedure instance, there is no procedure 
instance number (i.e. the procedure instance number contains a null 
value)".

ASN.1 - Your proposal to replace 
"secondaryProcedure [1] IntPos" by
"secondatyProcedure [1] ProcedureInstanceNumber" does not bring anything 
as this new type is not used elsewhere and will force the implementers to 
look for an additional type.
The ASN.1 is not changed.

B. I will remove the 2nd part of the sentence to read:
"3.3.2.5.2 The procedure-type shall uniquely identify the type of 
procedure."

If you disagree, please let me know.

Best regards
Yves





"John Pietras" <john.pietras at gst.com> 
Sent by: css-csts-bounces at mailman.ccsds.org
27/01/2011 22:10

To
<Yves.Doat at esa.int>
cc
css-csts at mailman.ccsds.org
Subject
[Css-csts] Issues regarding procedure-instance-identifier






Yves,
I just came across a few issues in the CSTS FW regarding the 
procedure-instance-identifier that I hadn't noticed before.
 
A. Paragraph 3.3.2.5.1 states:
"The procedure-instance-identifier shall consist of:
a)      the procedure-type (e.g. Buffered Data Delivery);
b)      the procedure role:
1)      the role of the Association Control procedure is always 
association control;
2)      the role of any other procedure is either prime procedure instance 
or secondary procedure instance;
c)      for secondary procedures: the procedure instance number;
d)     for prime procedure instance, the procedure instance number 
contains a null value."
 
As currently constructed, this section begs the question of whether there 
is a procedure instance number when the procedure is Association Control. 
I looked at the corresponding ASN.1 and found:
ProcedureInstanceId        ::=  SEQUENCE
{    procedureType        ProcedureType
,    procedureInstanceNumber    CHOICE
{    primeProcedure  [0] NULL
,    secondaryProcedure [1]     IntPos
,    associationControl [2]     NULL
}
}
 
Although the ASN.1 answers the question about procedure instance number 
for the AC procedure, there is inconsistency between the text and the 
ASN.1. E.g., there is no mention of "role" in the ASN.1, although it is 
encoded (in a sense, backwards) as part of the procedureInstanceNumber 
parameter. 
 
I'd like to suggest the following changes to clarify the text and make the 
ASN.1 more-closely map to it.
- Change paragraph 3.3.2.5.1 to read:
"The procedure-instance-identifier shall consist of:
a)      the procedure-type (e.g. Buffered Data Delivery);
b)      the procedure role:
3)      the role of the Association Control procedure is always 
association control;
4)      the role of any other procedure is either prime procedure instance 
or secondary procedure instance;
c)      for secondary procedures: the procedure instance number;
d)     for the prime procedure instance and the association control roles, 
there is no procedure instance number." 
 
[I suggest "there is no procedure instance number" instead of "the number 
contains a null value" because numbers are not null - that's an ASN.1 way 
of saying that the number doesn't exist or isn't applicable]
 
- Change the corresponding ASN.1 to read
ProcedureInstanceId        ::=  SEQUENCE
{    procedureType        ProcedureType
,    procedureRole   CHOICE
{    primeProcedure  [0]      NULL
,    secondaryProcedure [1]     ProcedureInstanceNumber
,    associationControl [2]     NULL
}
}
procedureInstanceNumber  ::= IntPos
 
B. Paragraph 3.3.2.5.2 states "The procedure-type shall uniquely identify 
the type of procedure: when invoking for the first time a procedure in a 
service, the invoker shall specify the procedure type and instance 
number;"  I am confused by the second half of this statement ("when 
invoking for the first time a procedure in a service, the invoker shall 
specify the procedure type and instance number"). It seems to be saying 
that only the first invocation associated with a procedure instance (e.g., 
a START invocation) contains the procedure type and instance number (and 
role?). But these are contained in every PDU, so I don't understand what 
this is trying to say.
 [Also, the paragraph should end in a period (".") and not a semicolon 
(";")]
 
Best regards,
John_______________________________________________
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