Subject: [Megaco] Syntax of MID

From: "Anand, Rashim" <[email-masked]>
Date: Thu, 25 Jul 2002 16:12:21 -0700

Hi,
   I am resending this mail to solicit comments.

Some time back we had a thread on MID being just a logical identifier going
on in the mailing list.
3015 Corr incorporates that concept (refer to section 8.3).

Shouldn't the ABNF and ASN definitions be modified to reflect that?
Currently, MID is
defined to be a choice of -

domain address / domain name / mtp address / device name

I think that MID could be better defined as -

mId = 1*( charsinMid )

charsinMid = ALPHA / DIGIT / ":" / "@" / "." / "[" / "]" /
                     "-" / ">" / "<" / "{" / "}" / "_" / "*" / "/" / "$"
    ;    basically the same characters which can be present in domain
name/address/mtp address/device name
    ;    some other characters could also be allowed

for ABNF and

      mId         OCTET STRING (SIZE(...)),

for ASN.

Such a modification would better reflect the logical identification purpose
of mid. The current
definitions IMPLICITLY restrict MID to domain name / address etc. This
restriction is inconsistent
with the nature of MID.

Based on above, serviceChangeMgcId and serviceChangeAddress (these are
currently of mId type) would have to be changed to something like -

serviceChangeAddress = ServiceChangeAddressToken EQUAL
                       ( ServiceChangeAddress / portNumber )
serviceChangeMgcId   = MgcIdToken EQUAL ServiceChangeAddress

ServiceChangeAddress = (( domainAddress / domainName )
                       [":" portNumber]) / mtpAddress / deviceName

for ABNF and something like -

serviceChangeMgcId  ServiceChangeAddress OPTIONAL,
in ServiceChangeParm with a comment - "the portNumber is not allowed
as a choice element in serviceChangeMgcId"
( the serviceChangeAddress parameter in contrast to the serviceChangeMgcId
  parameter can have just the portNumber )

for ASN.

Thank,
- Rashim

_______________________________________________
Megaco mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/megaco

---

From: [email-masked]
Date: Fri, 26 Jul 2002 19:05:06 +0530

Hi Christian

Though many times it has been cleared that the MID is logical identifier and
does not reflect the transport address, but the syntax definition does creates
confusion. I think changing the syntax also would remove the confusion
altogether.

Regards
vivek

Christian Groves <[email-masked]> on 07/26/2002 10:25:34 AM

To:   "Anand, Rashim" <[email-masked]>
cc:   "[email-masked]'" <[email-masked]> (bcc: Vivek Bansal/HSS)

Subject:  Re: [Megaco] Syntax of MID

Hello Rashim,

What is it that you want to do that the MID definition doesn't allow? People
have agreed that MID is logical but the current definition is rather flexible.
Device Name allows up to 64 characters. I do not see the point changing MID just
because people have agreed that its logical.

Regards, Christian

---

From: [email-masked]
Date: Fri, 26 Jul 2002 19:05:06 +0530

Hi Christian

Regards
vivek

Hello Rashim,

Regards, Christian

---

From: "Kevin Boyle" <[email-masked]>
Date: Fri, 26 Jul 2002 10:33:11 -0400

I have to agree with Christian.  A change here is far more impacting than
just removing confusion.  Everybody's parsers would have to be altered to
accept the new syntax.  For established implementations, this may not be a
trivial matter.

While this change may reduce confusion (although even that isn't
guaranteed), I don't see how that outweighs the negative impact that it
would have on existing implementations.

Kevin

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Friday, July 26, 2002 9:35 AM
To: Christian Groves
Cc: Anand, Rashim; [email-masked]'
Subject: Re: [Megaco] Syntax of MID

Hi Christian

Though many times it has been cleared that the MID is logical identifier and
does not reflect the transport address, but the syntax definition does
creates
confusion. I think changing the syntax also would remove the confusion
altogether.

Regards
vivek

Christian Groves <[email-masked]> on 07/26/2002 10:25:34
AM

Hello Rashim,

What is it that you want to do that the MID definition doesn't allow? People
have agreed that MID is logical but the current definition is rather
flexible.
Device Name allows up to 64 characters. I do not see the point changing MID
just
because people have agreed that its logical.

Regards, Christian

---

From: [email-masked]
Date: Fri, 26 Jul 2002 20:47:16 +0530

Hi Kevin,
I think while discussing about the changes related to MID, one should take into
account the correct philosophy and intent behind it. Any change or enhancement
should not just be overlooked since it would affect the implementations. The
effect here would not be much as it just relates to syntax.

Anyway for the changes contained in v2 draft as compared to v1, the
implementations would have to change as per the new draft since all these are
justified.

Thanks and Regards,
Prashant Jain

"Kevin Boyle" <[email-masked]> on 07/26/2002 08:33:11 PM

To:   Vivek Bansal/HSS@HSS, Christian Groves <[email-masked]>
cc:   "Anand, Rashim" <[email-masked]>, "[email-masked]'"
      <[email-masked]> (bcc: Prashant Jain/HSS)

Subject:  RE: [Megaco] Syntax of MID

Kevin

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Friday, July 26, 2002 9:35 AM
To: Christian Groves
Cc: Anand, Rashim; [email-masked]'
Subject: Re: [Megaco] Syntax of MID

Hi Christian

Regards
vivek

Hello Rashim,

Regards, Christian

---

From: [email-masked]
Date: Fri, 26 Jul 2002 20:47:16 +0530

Hi Kevin,

Thanks and Regards,
Prashant Jain

Kevin

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Friday, July 26, 2002 9:35 AM
To: Christian Groves
Cc: Anand, Rashim; [email-masked]'
Subject: Re: [Megaco] Syntax of MID

Hi Christian

Regards
vivek

Hello Rashim,

Regards, Christian

---

From: "Kevin Boyle" <[email-masked]>
Date: Fri, 26 Jul 2002 10:33:11 -0400

Kevin

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
Sent: Friday, July 26, 2002 9:35 AM
To: Christian Groves
Cc: Anand, Rashim; [email-masked]'
Subject: Re: [Megaco] Syntax of MID

Hi Christian

Regards
vivek

Hello Rashim,

Regards, Christian

---

From: "Kaul, Bharat" <[email-masked]>
Date: Fri, 26 Jul 2002 10:42:47 -0700

Kevin/Christian, 

 The new proposed syntax (part of which reproduced below) essentially has
same characters that are currently allowed. So it should not affect any
parser implementations. But it will definitely help reducing confusion. 

> charsinMid = ALPHA / DIGIT / ":" / "@" / "." / "[" / "]" /

For people who are just picking up on megaco and have not necessarily
followed discussions for last 2 years, it definitely will be helpful. The
proposed changes seem to clear up the syntax rather than affect any
implementation.

- Bharat

-----Original Message-----
From: Kevin Boyle [mailto:[email-masked]]
Sent: Friday, July 26, 2002 7:33 AM
To: [email-masked]; Christian Groves
Cc: Anand, Rashim; [email-masked]'
Subject: RE: [Megaco] Syntax of MID

Kevin

---

From: "Kaul, Bharat" <[email-masked]>
Date: Fri, 26 Jul 2002 10:42:47 -0700

Kevin/Christian, 

- Bharat

-----Original Message-----
From: Kevin Boyle [mailto:[email-masked]]
Sent: Friday, July 26, 2002 7:33 AM
To: [email-masked]; Christian Groves
Cc: Anand, Rashim; [email-masked]'
Subject: RE: [Megaco] Syntax of MID

Kevin

---

From: Aleksandr Ryabin <[email-masked]>
Date: Fri, 26 Jul 2002 14:24:39 -0400

Hi,

It might (or might not depending on particular implementation) be true for 
text
encoding (I mean no parser changes), but definitely not true for ASN.1, thus
the change will basically break backward compatibility.

Although I do agree that for new versions we should fix any inconsistencies
found so far, the changes should not break anything. Making the change
to MId encoding (for new versions) will break backward compatibility with
older versions since the very first SC must be compatible across all the
versions for MG-MGC protocol version negotiation.

"11.3  Negotiation of protocol version" is very clear and strict about it:
...
    "When extending the protocol with new versions, the following rules
    should be followed:

    1) Existing protocol elements, i.e. procedures, parameters,
       descriptor, property, values, should not be changed unless a
       protocol error needs to be corrected or it becomes necessary to
       change the operation of the service that is being supported by
       the protocol."
...

Thanks.
         Aleks

---

From: Aleksandr Ryabin <[email-masked]>
Date: Fri, 26 Jul 2002 14:24:39 -0400

Hi,

Thanks.
         Aleks

---

From: "Kaul, Bharat" <[email-masked]>
Date: Fri, 26 Jul 2002 11:51:28 -0700

Yes, I agree that ASN.1 seems an issue but I think most of the ASN.1
implementations today anyways have issue of  dealing with  implementations
sending MID as Octet Strings rather than the structure defined in ASN.1
(Taking off from our discussions on the mailing list as the basis)

I suppose that implies that anyone having ASN.1 parser today OR writing
ASN.1 parser going forward has to conceptually worry about following issues:

1) The packets received may has MID encoded as Octet String (as some
implmentations will assume based on the discussions on the mailing list that
MID is a logical string) or as a structure as defined in current ASN.1

2) Conceptually speaking, the parser output, however, in both cases must be
a logical identifier for protocol engines to deal with. How that happens is
an implementation issue.

So I already see interoperability issues here unless we impose that ASN.1
structures have to be followed irrespective of semantics of the element.
Then the parsers need to deal with point (2) only.

We have definitely CORRECTED our definition of MID from the earliest
understanding of it over last 2 years. In spirit of Section 11.5, I think
may be able to correct the syntax and help implementors by making their
lives simpler :). 

On a side note, do we have any estimate on how many ASN.1 implementations
exist ? ( I am aware of only 4).

- Bharat

-----Original Message-----
From: Aleksandr Ryabin [mailto:[email-masked]]
Sent: Friday, July 26, 2002 11:25 AM
To: Kaul, Bharat; [email-masked]
Cc: 'Kevin Boyle'; [email-masked]; Christian Groves; Anand, Rashim
Subject: RE: [Megaco] Syntax of MID

Hi,

Thanks.
         Aleks

---

From: "Kaul, Bharat" <[email-masked]>
Date: Fri, 26 Jul 2002 11:51:28 -0700

- Bharat

-----Original Message-----
From: Aleksandr Ryabin [mailto:[email-masked]]
Sent: Friday, July 26, 2002 11:25 AM
To: Kaul, Bharat; [email-masked]
Cc: 'Kevin Boyle'; [email-masked]; Christian Groves; Anand, Rashim
Subject: RE: [Megaco] Syntax of MID

Hi,

Thanks.
         Aleks

---

From: "Kevin Boyle" <[email-masked]>
Date: Fri, 26 Jul 2002 15:44:42 -0400

I would much rather have some text added stating explicitly that the mID is
only a logical identifier, then to alter the encodings.  Changing the ABNF
and ASN.1 encodings for this is an attempt to fix something that isn't
broken, whether the philosophy behind the existing encoding is flawed or
not.

Kevin

-----Original Message-----
From: Kaul, Bharat [mailto:[email-masked]]
Sent: Friday, July 26, 2002 2:51 PM
To: 'Aleksandr Ryabin'; [email-masked]
Cc: Boyle, Kevin [NCRTP:3R90:EXCH]; [email-masked]; Christian
Groves; Anand, Rashim

- Bharat

-----Original Message-----
From: Aleksandr Ryabin [mailto:[email-masked]]
Sent: Friday, July 26, 2002 11:25 AM
To: Kaul, Bharat; [email-masked]
Cc: 'Kevin Boyle'; [email-masked]; Christian Groves; Anand, Rashim
Subject: RE: [Megaco] Syntax of MID

Hi,

Thanks.
         Aleks