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Subject: Re: [soa-rm] David Linthicum Says: "ESB versus Fabric.Stop It!"
In fact, I do not think that policy fits in so neatly. If by layers, you mean a technology stack, then that represents a bottom-up, implementation oriented, view of the SOA. It may be appropriate for an RA to be modeled as that kind of layer, it does not seem appropriate for a reference model. On the other hand, I do think that the RM is layered on top of a different RM (Resource Model). The technical term for that kind of layering is *supervening*. Frank On May 24, 2005, at 1:08 PM, Vikas Deolaliker wrote: > > All of these facets of the RM can be built upon the layered > approach as the > networking world has demonstrated. For example, policy can be > implemented at > policy enforcement point (PEPs). All of these facets at an abstract > level > need a mechanism for state transfer and mechanism for state > coherence i.e. > synching local state with global state. Those mechanisms are easier > to build > in a layered approach. > > But before we do that, we need to agree if layered approach is the > right > approach. > > Vikas > > > -----Original Message----- > From: Francis McCabe [mailto:fgm@fla.fujitsu.com] > Sent: Tuesday, May 24, 2005 10:11 AM > To: vikas@sonoasystems.com > Cc: 'Michael Stiefel'; 'Chiusano Joseph'; soa-rm@lists.oasis-open.org > Subject: Re: [soa-rm] David Linthicum Says: "ESB versus Fabric.Stop > It!" > > And what about application semantics, policy application, service > management, security services, service intermediaries, etc. etc. etc.? > > On May 24, 2005, at 10:01 AM, Vikas Deolaliker wrote: > > >> >> Frank, >> >> Messages are abstract its binding to a communication model >> (synchronous vs >> asynchronous), format (SOAP vs. plan XML) or invocation model (SOAP >> vs REST) >> is architecture specific. >> >> About the arbitrariness of the layers. I beg to differ. The lowest >> layer is >> deals with transport endpoints while the layers above successively >> deal with >> higher abstraction of transport endpoints. For example Layer 2 >> deals with >> service endpoint and Layer 3 with session endpoint and Layer 4 with >> process >> endpoint. This is a clean partition. >> >> A reference model should drive multiple architectures. The layered >> approach >> does exactly that. >> >> >> Vikas >> >> >> >> -----Original Message----- >> From: Francis McCabe [mailto:fgm@fla.fujitsu.com] >> Sent: Tuesday, May 24, 2005 8:46 AM >> To: Michael Stiefel >> Cc: vikas@sonoasystems.com; 'Chiusano Joseph'; soa-rm@lists.oasis- >> open.org >> Subject: Re: [soa-rm] David Linthicum Says: "ESB versus Fabric.Stop >> It!" >> >> This stuff appears to be off topic for a reference model. >> >> These layers are extremely implementation oriented; and I submit, >> somewhat arbitrary. There is more in life than sending messages! >> >> Frank >> >> On May 23, 2005, at 6:47 PM, Michael Stiefel wrote: >> >> >> >>> +1 >>> >>> Michael Stiefel >>> >>> At 01:31 PM 5/23/2005, Vikas Deolaliker wrote: >>> >>> >>>> >>>> One could potentially map the SOA levels discussed in this blog to >>>> layers in a SOA-RM. >>>> >>>> Layer 1: Messaging/Queing with routing and transformation of >>>> messages. The endpoints for this layer are transport endpoints. >>>> >>>> Layer 2: Mediation Layer or Brokering Layer. The endpoints to this >>>> layer are the service endpoints. Endpoints are discovered using a >>>> discovery protocol (like DNS). >>>> >>>> Layer 3: Session Layer. The endpoints to this are session >>>> endpoints. Session endpoints can be all on one service endpoint or >>>> multiple. >>>> >>>> Layer 4: Process Layer. This is the choreography/orchestration >>>> layer at which new services can be developed. >>>> >>>> The RM then would need to define the notion of protocol data unit >>>> that traverses up/down and in between two of these stacks. >>>> (analogous to OSI). >>>> >>>> Thanks >>>> Vikas >>>> >>>> From: Chiusano Joseph [mailto:chiusano_joseph@bah.com] >>>> Sent: Monday, May 23, 2005 4:19 AM >>>> To: soa-rm@lists.oasis-open.org >>>> Subject: [soa-rm] David Linthicum Says: "ESB versus Fabric.Stop >>>> It!" >>>> >>>> Forwarding a very interesting and pertinent piece[1] from David >>>> Linthicum's (CTO of Grand Central) blog, titled "ESB versus Fabric. >>>> Stop It!". David also discusses 6 different "levels" of SOA, >>>> ranging from simple single point-to-point SOAP messages (Level 0) >>>> to SOA that incorporates orchestration (Level 5). >>>> >>>> Joe >>>> >>>> [1] http://www.webservices.org/index.php/ws/content/view/full/63539 >>>> >>>> Joseph Chiusano >>>> Booz Allen Hamilton >>>> Visit us online@ http://www.boozallen.com >>>> >>>> >>>> >> >> >> >> > > >
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