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Subject: RE: [soa-rm] David Linthicum Says: "ESB versus Fabric.Stop It!"
> -----Original Message----- > From: Rex Brooks [mailto:rexb@starbourne.com] > Sent: Wednesday, May 25, 2005 1:27 PM > To: Chiusano Joseph; soa-rm@lists.oasis-open.org > Subject: RE: [soa-rm] David Linthicum Says: "ESB versus > Fabric.Stop It!" > > I think a single service and a single service consumer for > that service comprise the definition of an atomic SOA. > Multiple services in a void of service consumers don't make > an SOA, only the potential for an SOA. We reflect that in > current thinking in our modeling in the draft 7 of the RM. > Figures 2 and 2.1, even though 2.1 precedes 2, and 2 shows > multiple services behind Service A. It might be wise for us > to have another diagram and arrange it so that the series runs: > 2.0 Components of a Service, 2.1 Components of a SOA, and 2.2 > Service Aggregation. I like that idea very much. Joe Joseph Chiusano Booz Allen Hamilton Visit us online@ http://www.boozallen.com > Ciao, > Rex > > At 9:13 AM -0400 5/25/05, Chiusano Joseph wrote: > > > -----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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