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Subject: [Fwd: Re: [ebXMLRegRepSWG] Registers and RegisterItems]



FYI, Here is a thread from OGC ebXML RegRep SWG regarding our 
Registration Procedures work.

-- 
Regards,
Farrukh

Web: http://www.wellfleetsoftware.com



--- Begin Message ---
Farrukh,

i agree, that XPDL is a very smart format for xml based exchange of 
process descriptions. I'm also using it for exchange of BPMN models.
But: Currently there are only 2 accepted standards for business process 
modeling:
- BMPN as a graphical notation standard with an arbitrary granularity 
for abstract management views as well as for detailed programmer's 
perspectives (OMG).
- And BPEL as an xml based standard for the execution level, suitable 
for modeling and orchestration of web services.
The lack of the both standards is, that BPMN does not specify a system 
independent exchange format (i.e. XML) for the specified models and on 
the other side the BPEL specification does not contain a graphical (or 
at least human readable) notation.
That gap is closed by XPDL.
My problem with XPDL is:

1. Using XPDL in addition to BPMN and BPEL implies a third standard with 
it's own versioning that has to be synchronized with the used versions 
of BPEL and BPMN.
2. The policy of OMG as the organization that standardizes BPMN 
postulates a metamodel for each standard (like MOF/XMI for UML). Such a 
metamodel is (meanwhile) specified by OMG, following a RFP. This is BPDM 
(Business Process Definition Metamodel). BPDM is a XSD and XMI based 
model for process descriptions (finalized Jul. 2008).
See: http://www.omg.org/spec/BPDM/1.0/
The big benefit of BPDM is that BPMN to BPEL mapping is part of the 
specification and thus formalized.
I have no practical experiences with BPDM as it is a very new standard - 
but i expect BPDM to be commonly accepted and supported by BP modeling 
tools in the near future (for instance Eclipse STP already supports BPDM).

René
>
> First my apologies for being unable to join the meeting and thanks to 
> Aaron for presenting the slides.
> Thanks René for your valuable input. The main purpose for presenting 
> this at the ebXML RegRep SWG
> is to make sure we get feedback from its membership and the OGC 
> community.
>
> Please see more inline below...
>
> Dr. René Thiele wrote:
>> All,
>>
>> in our wednesday afternoon joint session (regrep-catalogue) we had a 
>> short discussion about Farrukhs question concerning the multiple 
>> registration of register items: "Is there a need?"
>> The short answer was "yes", because it's allowed in ISO 19135 (even 
>> if it's unusual) - the according n:m aggregation is shown in 8.1.
>> This short question and short answer give us bag of aspects to 
>> discuss about.
>>
>> First, the definition (ISO 19135): Registration of an item is defined 
>> as the "assignment of a permanent, unique, and unambiguous identifier 
>> to an item". (4.1.12).
>>   
>
> That is consistent with definition of RegistryObject in ebXML RegRep 
> of which the proposed RegisterType is a descendant class.
>
>> 1. ISO 19135 describes the use of "externally specified items" and 
>> references (7.3.2.1). But it does not formally specify, who is (in 
>> that case) responsible for the uniqueness of the item identifier and 
>> the consequences for the registration procedures.
>>   
>
> In the ebXML RegRep proposed feature the ChangeProposalSubmitter at 
> SubmittingOrganization is responsible for providing all aspects 
> including unique id for items in a register.
>
>> 2. (Lydia mentioned after the meeting) Re-using items in a submission 
>> procedure means, that the business rules must be unique for all 
>> registers of a registry. 
>
> The proposal simply states that policies (business rules) are assigned 
> at the register level.
> It does not mandate or preclude that the same policies may be used by 
> multiple registers.
>
>> There might occur problems if (for instance) a Featuretype register 
>> and a Portrayal register should be managed in the same registry and 
>> consequently according to the same business rules.
>>   
>
> The proposal allows for Featuretype register and a Portrayal register 
> in the same registry to have same or different governance policies.
>> 3. Once registered, items can be registered by other registers:
>> In that case, the item gets a second AdditionManagementInformation 
>> record with consequences for the item status:
>> - item i is registered in register A,
>> - item i is registered in register B,
>> - someone proposes a retirement for item i in register B
>> => itemStatus(i) = retired (in A and B) (see 8.8.4)
>>   
>
> This scenario is currently precluded in the proposal and logged as an 
> issue.
> The argument for not allowing an item to be registered in more than 
> one Register
> is that it would would require the item to be governed by more than 
> one set of policies
> which could possibly be conflicting.
>
> The proposal allows for a Register to be replicated and kept 
> synchronized in another registry.
> In this scenario it is managed by the same set of policies in both 
> registries.
>
> For simplicity the first release plans to not allow edits of 
> replicated Registers but only the source Registers.
> This may be relaxed in future versions.
>
>> In real life the register manager and the control body should not 
>> allow that situation and reject the proposal - but this is not 
>> formalized.
>>   
> I agree. I think this is the same argument for not allowing an item to 
> be in more than one Registers?
>> 4. ISO 19135 supports 3 kinds of registers: simple, multi-part and 
>> hierarchical (see 7.1.1). How to deal with this concepts in a regrep 
>> environment and semantic?
>>   
>
> Under the proposal, a RegisterType is a sub-class of 
> RegistryPackageType. This means that a Register can have other 
> Registers as sub-Registers (hierarchical case) and can have any mix of 
> RegistryObjects as items. Thus there is no distinction between simple 
> and multi-part Registers. Is that a problem? What are we losing by not 
> having that distinction?
>
> Another area of concern is how best to make the business process be 
> configurable. XPDL has been suggested but I am concerned about whether 
> we need the complexity it introduces. I am personally undecided on 
> this issue.
>
> Thanks again for starting the discussion on this topic.
>


-- 
--------------------------------------
Dr. René Thiele

CPA Systems GmbH
Grantham-Allee 2-8
D-53757 Sankt Augustin

Tel.: +49(0)2241-2594–0
Fax.: +49(0)2241-2594-29

thiele@supportgis.de
www.cpa-systems.de

--------------------------------------
Handelsregister: 

HRB 9706, Amtsgericht Siegburg

Geschäftsführer:
	
Dr.-Ing. habil. Christoph Averdung
Dr.-Ing. René Thiele
Dr.-Ing. Matthias Ellsiepen




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