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Subject: Re: [soa-rm] David Linthicum Says: "ESB versus Fabric.Stop It!"
It would be far to concrete for a reference model to dive into infrastructure and services to support it. Duane Chiusano Joseph wrote: ><Quote> >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. ></Quote> > >Which implies that we may want to distinguish between "infrastructure" >and "application" services for our SOA RM (not necessarily advocating, >just pointing out the notion). That is, as long as this notion is not >too concrete for the RM - if so, it may be part of an RA. > >Joe > >Joseph Chiusano >Booz Allen Hamilton >Visit us online@ http://www.boozallen.com > > > > >>-----Original Message----- >>From: Christopher Bashioum [mailto:cbashioum@mitre.org] >>Sent: Wednesday, May 25, 2005 9:40 AM >>To: soa-rm@lists.oasis-open.org >>Subject: RE: [soa-rm] David Linthicum Says: "ESB versus >>Fabric.Stop It!" >> >> 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 >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>> >>>> >> >> >> >>
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