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Subject: RE: [soa-rm] David Linthicum Says: "ESB versus Fabric.Stop It!"
Duane, I agree with you. There is no point describing a service if a link to its endpoint cannot be found. Does this then imply that we have a "must-have" relationship which is far stricter than just a dependency? Finally, why describe a service if it cannot be consumed, for future reservations maybe similar to XML namespaces? Comments anyone... Wes -----Original Message----- From: Duane Nickull [mailto:dnickull@adobe.com] Sent: 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. 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 >>>>>>> >>> > >
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