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Subject: RE: [soa-rm-ra] Please re-read Sect 4.3.4 of soa-ra-cd-02

Here is my attempt to slightly re write the section. I send it out several month ago, but based on yesterday it still seems relevant. I can do some more work, if we agree that it is a proper direction


From: Ken Laskey [mailto:klaskey@mitre.org]
Sent: Wednesday, June 02, 2010 5:12 PM
To: 'Estefan, Jeff A (3100)'; soa-rm-ra@lists.oasis-open.org
Subject: RE: [soa-rm-ra] Please re-read Sect 4.3.4 of soa-ra-cd-02




A useful analogy that comes to mind is when we built an addition on our house.  We hired an architect and a general contractor, and the general contractor was responsible for hiring plumbers, carpenters, carpet installers, etc.  The general contractor had the role of the composite service.  I sometimes saw the plumber when plumbing work was being done (often didn’t) but didn’t usually know the details of what the plumber was doing or when.  (The general contractor did mention at some point that the plumber was two days late and there would be some workarounds.)  Same for the other subcontractors.  I knew there were dependencies but I knew nothing of the details and assumed these would be handled adequately by the general contractor as part of his service.  If there were independent policies on the part of the subcontractors, I was unaware of these and only dealt with the policies of the general contractor.  For example, there was a payment schedule and I assume the general contractor took into account the need to pay the subcontractors, but I only dealt with the policies as specified by the general contractor (my composite service).


I look at the provider of a composite service as the consumer of all its components, and the general contractor dealing with each of his subcontractors is no different in general from me dealing with him.  Also, the general contractor coordinating among the subcontractors was similar to me coordinating with the general contractor and the architect.


One place where I may not understand your perspective and have trouble relating to my home addition example is lines 2338-2346 when you talk about a Service Management Service.  You say this service needs visibility into the composition so it can manage dependencies, but I see managing dependencies as the job of the composite service.  Now the composite service may make use of tools to monitor the components (or the ecosystem, in general) and may make use of operation research tools to balance complex tradeoffs among requirements.  However, these are tools (possibly services) used by the composite to manage its requirements and dependencies.  I do not think of there being some independent management entity unless the full management function was subcontracted by the composite.


Quick other points:

-          Description information is never complete but various subsets of “complete” description should contain consistent information

-          A given service may have more than one endpoint but I would expect a single information model and, possibly, a single process model.  Imagine the difficulty in writing a clear, machine-processible description if this is not the case.

-          No service operates in a vacuum, and trying to convince people that anything infrastructure is not a service will be a very hard sell.


Enough for now.




Dr. Kenneth Laskey

MITRE Corporation, M/S H305              phone: 703-983-7934

7515 Colshire Drive                                    fax:        703-983-1379

McLean VA 22102-7508


From: Estefan, Jeff A (3100) [mailto:jeffrey.a.estefan@jpl.nasa.gov]
Sent: Wednesday, June 02, 2010 1:11 PM
To: soa-rm-ra@lists.oasis-open.org RA
Subject: [soa-rm-ra] Please re-read Sect 4.3.4 of soa-ra-cd-02


RAF Colleagues,


A very interesting discussion ensured today on the topic of atomic vs composite services.  I’d like to encourage everybody who participated in the discussion to re-read Sect 4.3.4 in its entirety prior to next week’s meeting and proposed (via e-mail in the interim if you like) some wording changes to the formal definitions captured in this section.  The reference document is soa-ra-cd-02 lines 2311 to 2350.


Remember that the original issue resolved around multiplicity of interfaces and descriptions and we did not even discuss that point today and for the atomic service case, the issue around the language of interacting with other services (which is accepted to change to use or rely on other services).


Indeed the importance of this distinction depends on one’s perspective but I ask that you imagine the challenges from a management point of view for a highly composed service in terms of management of policies and contracts of each of the services that make up the composite service.  I think this has some real practical implications and they are not trivial.




 - Jeff

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Composition of Services.docx

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