[scrm-wg] New template and OSI mapping question

[Franco Travostino]

My 2 cents on the question that went unanswered in today's SCRM call:

The mapping to the OSI stack is controversial (especially at layers 
greater than 3!) because no one follows the OSI stack as a formal 
design center. It's rather an after-the-fact orientation tool.

Not surprisingly, HTTP has Layer 5 traits (session: e.g., the reuse 
of TCP flows) and Layer 6 traits (presentation: e.g., the MIME-like 
encoding). Tim Berners Lee et al. called it an "application-level 
protocol" in RFC 1945 
http://www.ietf.org/rfc/rfc1945.txt?number=1945. The mapping was 
equally troublesome 20 year ago. TCP itself spreads between Layer 5 
and Layer 4 and is not a pure Layer 4 play like most diagrams show. 
Likewise, the FTP application was recognized having elements of 
session, presentation, and application layers.

>SOAP and all WS-* are above layer 8

The Layer 8, 9, and 10 have long been the target of dry humor (as in 
being money, politics, religion respectively).  It's difficult to be 
taken seriously when it comes to those layer numbers. I would think 
it's best to stay within the canonical 7 layers (and possibly 
grouping protocol in 7a, 7b, 7c realms etc if further differentiation 
is warranted).

>On the other hand, (2) maps
>HTTP to layer 5 (session) and SOAP to layer 6 (presentation).

This can practically work, while recognizing that a giant 
sledgehammer has been dropped on HTTP (it can be argued that it's a 
layer 6 protocol just as well).

-franco

Franco Travostino, Director
Advanced Technology, CTO Office
Nortel
600 Technology Park
Billerica, MA 01821 USA
Tel:  978 288 7708
Fax: 978 288 4690




At 06:01 AM 8/1/2005, Hiro Kishimoto wrote:

>Hi all,
>
>I've update master template from v3.6 to v3.6.1 by filling in
>URIs for FCAPS, ISO OSI, and CIM information. The latest template
>is attached.
>
>I have two URIs for ISO OSI information.
>
>(1) 
><http://en.wikipedia.org/wiki/OSI_model>http://en.wikipedia.org/wiki/OSI_model
>(2) http://www.looselycoupled.com/opinion/2003/saruk-osi-infr0905.html
>
>(1) is conventional TCP/IP like mapping and (2) is Web services
>focused mapping. In the farmer mapping HTTP is layer 7 (application)
>and SOAP and all WS-* are above layer 8. On the other hand, (2) maps
>HTTP to layer 5 (session) and SOAP to layer 6 (presentation).
>
>I guess this is controversial issue, but we need single mapping rule
>for comparison. If we use (1) mapping, many summary sheets fall in to
>layer 7 and question #12 becomes meaningless. In order to have
>meaningful grouping, I think mapping (2) is better.
>
>Your thoughts?
>--
>Hiro Kishimoto
>
>
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