Re: [SAM] Review of draft-samrg-sam-baseline-protocol-00

Marc Petit-Huguenin <petithug@acm.org> Thu, 24 November 2011 16:52 UTC

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Date: Thu, 24 Nov 2011 08:52:30 -0800
From: Marc Petit-Huguenin <petithug@acm.org>
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Subject: Re: [SAM] Review of draft-samrg-sam-baseline-protocol-00
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Hi,

More comments below.

On 11/17/2011 08:29 AM, Dr Mario Kolberg wrote:
> Dear Marc,
> 
> many thanks for your review. See below for our responses:
> 
> On 06/11/2011 18:11, Marc Petit-Huguenin wrote:
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>> Sorry for the delay in reviewing this.  I waited to base the review on an
>> implementation, but unfortunately I never got the time to do so.  So this is
>> only a partial review.
>>
>>

[...]

>> 3. Section 7.2.1 structure definition
>>
>> The Dictionary type is not defined in this spec.
>>
>> Also I would suggest to follow the standard convention of using lowercase for
>> the character of a field.
> Reload defines DictionaryEntry (section 6.2.3). Dictionary is a 'data model'
> (section 6.2).

But Dictionary is never defined as a data structure in RELOAD, and even if it
was defined as an array of DictionaryEntry, that would not match the text
("name-value list of properties...") - the closest structure definition that
matches this text in RELOAD would be IceExtension.

I would suggest to explicitly define Dictionary as follow:

struct {
  opaque name<0..2^16-1>;
  opaque value<0..2^16-1>;
  } DictionaryElement;

struct {
  DictionaryElement elements<0..2^16-1>;
  } Dictionary;

>> 4. Section 7.2.[2-5]
>>
>> RELOAD message are client/server based.  A request is sent and retransmitted
>> until a matching response is received.  I am sure how the
>> Join/JoinAccept/JoinConfirm/JoinDecline mechanism is working inside this
>> framework.
>>
> For Join,  JoinAccept and JoinReject  are matching responses.

But this is not how the RELOAD routing works.  RELOAD says that a response uses
the code value + 1 of the request, excepted for the ErrorResponse.  The problem
here is that a standard implementation of RELOAD will not be able to process
correctly theses messages.  If the goal is to change the routing algorithm, I
would suggest to add a ForwardingOption to each message, with the
FORWARD_CRITICAL flag set, so standard RELOAD implementations do not even try to
route these.

[...]

- -- 
Marc Petit-Huguenin
Personal email: marc@petit-huguenin.org
Professional email: petithug@acm.org
Blog: http://blog.marc.petit-huguenin.org
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