Subject: [uddi-spec] some comments on "Using BPEL4WS in a UDDI registry" Technical Note
I think the BPEL technical note is pretty good but it seems to me that there is a potentially very useful little bit of meta-data missing:
An Abstract BPEL is supposed to model a multi-party long running process. The series of interactions in the process are broken down into bilateral conversations modelled by the partnerlink Type element that defines the two roles (and the port types they implement) involved in the conversation.
It seems to me that a common application of abstract BPEL will be to model B2B processes and the choreography of interactions within a two-party conversation. For two parties to engage in such a conversation they must play COMPLEMENTARY roles in the conversation. Accordingly a common query that might be made by a business entity that plays the role “seller” in the “eancom procurement process” bpel could be “show me all business Entities in my geography that provide a business service that supports the role seller in the eancom procurement process”. In short the seller is trying to find customers that have a compatible (ie complementary) interface.
Now the problem is that the TN (so far as I can see) only results in publication of one tModel for the process. The TN says that “all port types used in the process” are listed in the process tModel using the wsdl portTypeReference tModel. If a particular bpel references (say) 4 port types in various namespaces, there is no way to support this query because we don’t know which of the four port types is linked to which role and therefore which ones are complementary. Would it not make sense to also have a tModel for each ROLE in the bpel (defined by the partnerlink types) and a new tmodel keyed reference that points to the “complementary role”. In this case the model would look more like:
Process tModel (with links to roles via a roleReference category bag element)
Role tModel (with links to the portTypes provided by the Role via the wsdl portType reference AND a link to the complementary Role with a new reference tModel)
PortType tModel – as per TN2 standard.
Also - just a point of clarification here, when the TN says that the process tModel references that “all port types used in the process” - I assume this means ALL port types in the BPEL, whether in an <invoke> element or a <receive> element? Ie all port types whether they are PROVIDED by the bpel or CONSUMED by the bpel? If so then my previous discussion make some sense. If only the portTypes PROVIDED by the bpel are included then the whole discussion around complementary roles is invalid and the eancom seller can’t find his potential customers.
In our implementation of UDDI in
Of course there is an entirely separate discussion about whether abstract BPEL is an appropriate standard to model collaborative B2B processes in the first place (they are really choreographies whilst bpel is an orchestration language). That aside, I am sure that at some point bpel will be targeted at describing abstract conversations and then this issue of how you represent them in uddi becomes quite important.
Sorry this is so late in the day (but it is still before the 3rd December deadline!).
Luc Clement [mailto:firstname.lastname@example.org]
Having provided sufficient time to review the "Using BPEL4WS in a UDDI Registry" Technical Note it is the UDDI Spec TC’s opinion this Technical Note is ready to be published. It is our intent to publish this TN by the end of this calendar year. That said, should you have additional feedback please provide it no later than 3 Dec so it may be considered prior to the expected ratification of the TN by this TC in mid-Dec.
We understand that there may be unresolved issues relating to the relevance of abstract processes as it relates to the WSBPEL specification. We would like to draw your attention to the fact that the TN applies to the BPEL4WS 1.1 specification submitted to the WSBPEL TC and which defines the concept of abstract processes. The decision to map BPEL4WS 1.1 was deliberate – the TN aims at addressing current market needs.
Luc Clement [mailto:email@example.com]
Dear WSBPEL Chairs,
The UDDI Spec TC has been working on a “Using BPEL4WS in a UDDI registry” Technical Note (TN) that it would like your input on before proceeding to ratify this TN.
The TN provides a mapping for publishing BPEL4WS abstract processes into a UDDI registry. The primary goals of mapping BPEL4WS artifacts to the UDDI model are to:
We would like to invite the BPEL TC to review and comment on the document and ask that you assign two or more reviewers.
The TN is posted at the following locations by format:
We would appreciate comments as soon as possible but preferably before 31 Aug 04. Please submit comments:
Thanks in advance
Co-Chair OASIS UDDI Spec TC