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Subject: Re: [soa-rm-ra] service execution context

While the EC is a pervasive concept throughout the RA, I believe that 
there is considerable merit in keeping the EC as a separate, 
architectural abstraction in the RA.  When Architects are building 
concrete architectures using the RA, I believe that having the EC as a 
point of view will be invaluable to them as they describe interactions 
between service participants.


Francis McCabe wrote:
> Well, could not resist this one ...
> In my mind the EC is the 'beaten path' that must exist for there to be 
> meaningful interaction between service participants. On that 
> interpretation, I agree with both Ken and Michael.
> However, I also saw that, in the RM, the EC represented all the 'gorp' 
> needed to establish the interaction. Necessary but distracting if gone 
> into in too much detail.
> From this PoV, I believe that a key function of the RA is to unpack 
> the EC sufficiently to explicate how you might realize a SOA. Hence, 
> you will not find much direct mention of the EC in the RA: it is 
> pervasive.
> Frank
> On Sep 24, 2007, at 7:36 AM, Ken Laskey wrote:
>> Michael,
>> You nailed it all the way!
>> Both technical (e.g. what are the communications protocols) and 
>> business (e.g. if I ask for a value and there is a US and a separate 
>> UK way of calculating the value, which one is chosen) aspects go into 
>> the execution context.  At one point in the RA write-up, I started 
>> thinking of its relationship to the log of an interaction and had 
>> some thoughts of the log as a capture of the execution context.  
>> There may be several decision points that go into sustaining an 
>> interaction, but if the same interaction is required later, you could 
>> want to make sure you execute the same conclusions and not re-ask the 
>> questions that might lead to different answers.
>> I have a very intuitive feel for the execution context (one I know 
>> Frank doesn't share ;-) ) so I welcome questions that help clarify it 
>> and find its right place in the RA.
>> Ken
>> On Sep 24, 2007, at 8:43 AM, Poulin, Michael wrote:
>>> Folks,
>>> I have another question (which is, probably, not the right time to 
>>> ask since the period of comments for 0.2 version is closed... but I 
>>> will try):
>>> I've just realised that the RA interprets 'service execution 
>>> context' from RM as "Within the RM, the execution context stood for 
>>> all the aspects of an information system that are needed to 
>>> facilitate interaction. A large part of the goals of the Reference 
>>> Architecture is to show how interaction is realized". Plus, 
>>> "Descriptions of the provider and consumer are the essential 
>>> building blocks for establishing the execution context of an 
>>> interaction." That is, it is a communication context.
>>> In another place: "The execution context can be thought of as a 
>>> series of answers to the questions of why would the participants be 
>>> willing to interact and whether such interaction is possible", i.e. 
>>> one can assume that the context may include business 
>>> conditions/context as a factor of willingness to interact. This 
>>> corresponds to the references to the policies in the RM's definition 
>>> (policies, which may apply as to the communication as to the 
>>> execution on the provider side and be agreed in the Service Contract).
>>> I have read the RM's definition of the execution context as both - 
>>> information AND business context of execution of the service rather 
>>> than just communication information system context. For example, 
>>> assume we have a service for calculating a fund price. We have 
>>> corporate divisions in the US and in the UK working with different 
>>> funds but in the same fund category. Besides different policies, the 
>>> calculation method is different (in the business definition) in the 
>>> US and the UK. That is, the service execution context from business 
>>> perspective is different. So, before reusing the service even in the 
>>> same information infrastructure, it is better to, at least, re-test 
>>> it even if no one bit of its implementation is changed.
>>> I think we have to clear state what is meant by  the service 
>>> execution context in the RA.
>>> Cheers,
>>> Michael Poulin
>>> Head of Business Analysis and Web Architecture
>>> Senior Manager, Web Delivery
>>> Fidelity Investments International
>>> ' +44-173-783-6038
>>> * michael.poulin@uk.fid-intl.com
>>> 8 http://www.fidelity.co.uk/
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>> ------------------------------------------------------------------------------------------ 
>> Ken Laskey
>> MITRE Corporation, M/S H305     phone:  703-983-7934
>> 7515 Colshire Drive                        fax:        703-983-1379
>> McLean VA 22102-7508

Don Flinn
Mansurus LLC
e-mail: flinn@alum.mit.edu
Tel: 781-856-7230

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