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Subject: RE: [soa-rm] David Linthicum Says: "ESB versus Fabric.Stop It!"


I think we need to make opacity optional simply to allow repurposing 
where there may be more than one possible set of application/prior 
services that can be aggregated in a way more easily consumed by a 
given consumer/repurposer.

Ciao,
Rex

At 9:39 AM -0400 5/25/05, Christopher Bashioum wrote:
>  Joe,
>
>I'm beginning to think that the question you are asking (and have been
>asking ; ) carries something more subtle that I don't believe we have
>addressed yet.  It is the idea of intent.  I have been of the impression
>that the intent of SOA is service opacity and location opacity (i.e., you
>can't see behind the interface (allows for replacement of parts) and you
>can't see where the service is on the network (implies discovery mechanism).
>But - when it comes to the actual services, the intent there is to create
>the interface in such a way as to allow for re-purposing.  In other words,
>as I create a service, I include as an implied requirement that it will be
>used by consumers I don't know in a way that I can't foresee. 
>
>It is this idea of intent that I think we are having a hard time capturing
>in the RM.  I think your concern about multiple services is another way of
>saying the same thing.  The problem with the number of services is it really
>may not capture the intent.  For example, if I have 4 services - is that
>really sufficient for an SOA?  I'm not sure.  However, if I have at least
>the infrastructure services that enable an SOA (yet to be defined, but
>conceptually referred to as an ESB, or discovery, messaging, and mediation -
>whatever) do I have an SOA?  Or yet again, if I have the infrastructure and
>one non-infrastructure service, do I then have an SOA?
>
>Intuitively, I think that if I have some minimal level of infrastructure
>(messaging, discovery, and mediation) and I expose one single
>non-infrastructure service on this infrastructure, I have an SOA.
>
>-----Original Message-----
>From: Chiusano Joseph [mailto:chiusano_joseph@bah.com]
>Sent: Wednesday, May 25, 2005 9:13 AM
>To: soa-rm@lists.oasis-open.org
>Subject: RE: [soa-rm] David Linthicum Says: "ESB versus Fabric.Stop It!"
>
>>  -----Original Message-----
>>  From: Duane Nickull [mailto:dnickull@adobe.com]
>>  Sent: Tuesday, May 24, 2005 2:56 PM
>>  To: Michael Stiefel
>>  Cc: soa-rm@lists.oasis-open.org
>>  Subject: Re: [soa-rm] David Linthicum Says: "ESB versus
>>  Fabric.Stop It!"
>>
>>  Endpoints are part of a service description IMO. 
>>  Orchestration of multiple services is out of the scope of 
>>  the core RM, much the same way as how multiple houses are
>>  positioned next to each other in a grid layout is
>>  un-necessary in order to define a RM for house.
>>
>>  A service or house do not have to exist amongst multiple
>>  houses in order to be services/houses.
>
>Which brings us back to what I believe is the single most important
>question for us to answer: Does one service constitute a SOA? Or are 2
>or more services required?
>
>If 2 or more services are required, then it seems to me that in order to
>call something a *SOA* reference model, the notion of multiple services
>must be incorporated - as that is the minimal amount of information
>necessary to *effectively* represent/model the "targeted entity" (which
>is SOA) for the intended audience.
>
>If one service constitutes a SOA, this implies that a SOA may have more
>than one service. It then seems to me that one has a choice for their
>RM: include only a single service in the model, or include multiple
>services. The question then becomes which approach enables the most
>effective representation for the intended audience.
>
>So as you see, I believe everything flows from this single most
>important question.
>
>Joe
>
>Joseph Chiusano
>Booz Allen Hamilton
>Visit us online@ http://www.boozallen.com
>
>>  Duane
>>
>>  Michael Stiefel wrote:
>>
>>  > Could we then conceive of endpoints and orchestration in such a
>>  > fashion? Or is the critical point aspect or attribute in which case
>  > > endpoint qualifies, but orchestration does not.
>>  >
>>  > To make a grammatical analogy, the RM defines a substantive, and
>>  > therefore adjectives (aspects and attributes) are part of
>>  the RM, but
>>  > verbs (actions) are not.
>>  >
>>  > (side note: I know verbs have aspect, but we are not using the term
>>  > that way).
>>  >
>>  > Michael
>>  >
>>  > At 02:34 PM 5/24/2005, Duane Nickull wrote:
>>  >
>>  >> Since Structural Integrity is an aspect of all houses, it could be
>>  >> part of a RM as an abstract concept.  Even if you do not
>>  explicitly
>>  >> design a house to have a certain set of structural integrity
>>  >> parameters, it still does.  It is not a component itself, just an
>>  >> aspect or attribute.
>>  >>
>>  >> Duane
>>  >>
>>  >>
>>  >> Michael Stiefel wrote:
>>  >>
>>  >>> I thought of structural integrity in terms of the entire
>>  house, not
>>  >>> just a wall, but I think your point remains the same.
>>  >>>
>>  >>> Granted that each architecture needs to specify its structural
>>  >>> integrity, but shouldn't the RM have the concept of structural
>>  >>> integrity since it is an abstract concept shared by all RAs.
>>  >>>
>>  >>> Michael
>>  >>>
>>  >>> At 02:06 PM 5/24/2005, Duane Nickull wrote:
>>  >>>
>>  >>>> The RM does not necessarily have to get into cardinality
>>  rules IMO,
>>  >>>> unless they are very obvious.  In the case of a house,
>>  you may not
>>  >>>> make consistent rules stating that every house has to
>>  have at least
>>  >>>> three walls since a wall can be curved or any number of
>>  walls from
>>  >>>> 3 up.  You may be able to infer from the relationships
>>  that there
>>  >>>> is a certain cardinality if the RM for a house said that
>>  each room
>>  >>>> has one door.
>>  >>>> That would declare an association between the number of rooms to
>>  >>>> the number of doors.
>>  >>>>
>>  >>>> Structural integrity is an aspect of a wall, which must be
>>  >>>> specialized for each architecture based on a number
>>  criteria.  The
>>  >>>> RM declares what the wall is and its' purpose, the architect has
>>  >>>> the job of specifying the actual walls to be used for each
>>  >>>> architecture and ensuring they map back to requirements.
>>  >>>>
>>  >>>> You are right - analogies are not definitions, however I
>>  have found
>>  >>>> them very useful in conveying the meaning.
>>  >>>>
>>  >>>> Duane
>>  >>>>
>>  >>>> Michael Stiefel wrote:
>>  >>>>
>>  >>>>> Does the RM understand that some of the concepts are unique and
>>  >>>>> some multiple (without an exact number, you could have one
>>  >>>>> circular wall, 3 walls, 4 walls, etc.)?
>>  >>>>>
>>  >>>>> Using your analogy, how does the RM deal with concepts such as
>>  >>>>> structural integrity. Structural integrity would apply to all
>>  >>>>> house RAs. In my way of thinking concepts such as endpoints or
>>  >>>>> orchestration are analogous to this.
>>  >>>>>
>>  >>>>> In the analogy I would see the reference architecture
>>  as Colonial
>>  >>>>> American Reference Architecture, or even more specifically
>>  >>>>> Colonial American Cape Ann, or Colonial American Greek Revival
>>  >>>>> reference architectures.
>>  >>>>>
>>  >>>>> Analogies are useful, but they are not definitions.
>>  >>>>>
>>  >>>>> Michael
>>  >>>>>
>>  >>>>> At 12:56 PM 5/24/2005, Duane Nickull wrote:
>>  >>>>>
>>  >>>>>> RA means Reference Architecture.  As per the previous
>>  emails on
>>  >>>>>> this subject, it is a generalized architecture.
>>  >>>>>>
>>  >>>>>> The relationship is that architects use a RM as a
>>  guiding model
>>  >>>>>> when building a RA.
>>  >>>>>>
>>  >>>>>> For example, if you are architecting a house, an RM
>>  may explain
>>  >>>>>> the concepts of gravity, a 3D environment, walls, foundations,
>>  >>>>>> floors, roofs, ceilings etc.  It is abstract however. 
>>  There is
>>  >>>>>> nothing specific like a wall with measurements such as 8 feet
>>  >>>>>> high.  Note that the RM has only one each of these things - it
>>  >>>>>> does not have 4, 16, 23 walls, just one as a concept.
>  > >>>>>> The architect may uses this model to create a specific
>>  >>>>>> architecture for a specific house (accounting for such
>>  things as
>>  >>>>>> property, incline, climate etc) or an architect MAY
>>  elect to use
>>  >>>>>> it to build a more generalized reference architecture.  The
>  > >>>>>> latter is often done by architects who design houses. 
>>  When they
>>  >>>>>> sell a house, they must often re-architect the RA for specific
>>  >>>>>> implementation details such as incline of land,
>>  climate, facing
>>  >>>>>> the sun etc..
>>  >>>>>>
>>  >>>>>> So why do we need a RM?  Simple - we now have logical
>>  divisions
>>  >>>>>> amongst the components of a house and what they mean. 
>>  That way,
>>  >>>>>> when a company says " we are a flooring company..", that is
>>  >>>>>> meaningful since we all know what that means.  The
>>  same applies
>>  >>>>>> to a roofing company.  Without the basic consensus on
>>  the logical
>>  >>>>>> divisions, a roofing contractor may also try to include the
>>  >>>>>> ceiling and walls as part of his offerings.
>>  >>>>>> That would not work and not allow the general
>>  contractor to build
>>  >>>>>> a house very easily since there may not be consensus upon the
>>  >>>>>> division of labor and components to build the house.
>>  >>>>>>
>>  >>>>>> Do you guys think an explanation of this nature may be good to
>>  >>>>>> include in the introduction section?
>>  >>>>>>
>>  >>>>>> Duane
>>  >>>>>>
>>  >>>>>> Chiusano Joseph wrote:
>>  >>>>>>
>>  >>>>>>> What is an RA? What is the relationship between an RM
>>  and an RA?
>>  >>>>>>> What is
>>  >>>>>>> the RM->RA path for SOA?
>>  >>>>>>>
>>  >>>>>>> Matt also submitted last week (I believe) that we may
>>  not even
>>  >>>>>>> need an RA. How should that change our notion of RM,
>>  if at all?
>>  >>>>>>>
>>  >>>>>>> Joe
>>  >>>>>>>
>>  >>>>>>> Joseph Chiusano
>>  >>>>>>> Booz Allen Hamilton
>>  >>>>>>> Visit us online@ http://www.boozallen.com
>>  >>>>>>>
>>  >>>
>>  >
>>  >
>>


-- 
Rex Brooks
President, CEO
Starbourne Communications Design
GeoAddress: 1361-A Addison
Berkeley, CA 94702
Tel: 510-849-2309


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