Re: [soa-rm-ra] An epiphany

[Francis McCabe <frankmccabe@mac.com>]

As far as descriptions is concerned ...

  There is this delicious intersection point where a private action  
'becomes' public in the sense that a complete understanding of the  
action is only possible in terms of a public/shared semantics. So, you  
may need description from a ecosystem perspective to facilitate the  
sharing of the semantics.
  However, I would note that (a) descriptions have a facilitating role  
not an enabling role (an analogy from natural communication: you do  
not need a dictionary to speak English, but it helps) and (b) it is  
not clear to me how much we need to elaborate the structure of such a  
description. In fact, I think we may well be elaborating it too  
deeply; a feeling that Danny has echoed several times.
  Systems of systems of systems is not the same as composition of  
services. It is more about "when in Rome, do as the Romans do..."
Frank
On Jan 16, 2009, at 8:30 PM, Ken Laskey wrote:

> Dang, Frank, I go away for a couple days and you go all wacko on  
> me :-)
>
> OK, my take.  Of course it has nothing to do with messages.   
> Information has to get from Participant A to Participant B and might  
> also depend on information provided by Participants C, D, and E.   
> Talking about message exchange buys us three things:
>
> 1) Everybody exchanges messages now and it gives the RA some  
> concrete grounding in a space that is familiar to most people.
>
> 2) I expect there is very little if anything messages add to the RA  
> than saying you need abstract (and eventually concrete) components  
> for message passing and processing if you're exchanging messages,  
> but it gives us the incentive to really consider if messages are  
> more than a specific use of the SOA machinery that other things  
> point out.
>
> 3) I forget right now, but there was a third.
>
> As you note, when you access and want to use information you get  
> from someone else, you have to understand it.  UDDI is based on the  
> assumption that this is not an issue.  Obviously, those folks never  
> went to an online vendor and tried to make use of the product  
> comparison tables.
>
> Description has nothing to do with messages, so getting rid of  
> messages doesn't get rid of description.  Description does, however,  
> critically need semantic engagement.  That is one of the drivers for  
> the section of description Danny always wants to kill because it  
> explicitly points out that whenever you use a term, you need to  
> disambiguate the vocabulary being used.  This sets the stage for  
> mediation which is needed all over the place if independent entities  
> are independently creating and providing resources.
>
> Your system of systems of systems looks nothing more than  
> compositions at various levels and for various types of resources.   
> I need more than semantic engagement for the service input values.   
> I also need it for policies, for technical assumptions, for ... .   
> That is where the execution context comes in because it is the  
> collection of the semantic engagements at various levels over the  
> various aspects of SOA.
>
> Now I don't see where this cuts the RA in half.  If it keeps the  
> length manageable, that's a plus, but I don't yet see it.
>
> Ken
>
> On Jan 16, 2009, at 12:24 AM, Francis McCabe wrote:
>
>> Hi Danny,
>> I realize that I have some explaining to do...
>>
>> I don't see Counts-as as being connected to semantic engagement; at  
>> least not at the moment.
>>
>> Like I said, this is really about the dichotomy/relationship  
>> between private internal action and publicly shared/understood  
>> interaction. In my view, the messaging system is, at this level of  
>> abstraction, simply a medium in which you can have such a public  
>> interaction. It is necessary to have such a medium because we are  
>> fundamentally talking about peer-to-peer models crossing ownership  
>> boundaries.
>>
>> On top of this, is the strong intuition that one can have multiple  
>> layers of ecosystem -- systems of systems of systems etc.
>>
>> One of the diagrams that we have drawn internally is like a spider  
>> plant:
>> <Spider Plant.pdf><ATT00001.htm>
>
> -----------------------------------------------------------------------------
> Ken Laskey
> MITRE Corporation, M/S H305      phone: 703-983-7934
> 7515 Colshire Drive                         fax:       703-983-1379
> McLean VA 22102-7508
>
>
>
>
>
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