- From: Francis McCabe <fgm@fla.fujitsu.com>
- Date: Fri, 4 Oct 2002 10:57:15 -0700
- To: www-ws-arch@w3.org
Begin forwarded message: > From: Francis McCabe <fgm@fla.fujitsu.com> > Date: Fri Oct 4, 2002 10:56:44 AM US/Pacific > To: "David Booth" <dbooth@w3.org> > Subject: Re: Top cloud in triangle/rectangle diagram > > An analysis of this kind would be a useful part of the architecture > spec itself; if for no other reason than to hammer home to the > reader(s) that there is more than one way of skinning the cat. > > Also of the essence is that however the originating agent discovers > the service, the document describing the service is what is critical > to the originating agent. > > Frank > > On Friday, October 4, 2002, at 10:39 AM, David Booth wrote: > >> At 09:40 PM 10/2/2002 -0400, Christopher B Ferris wrote: >> >>> David, >>> >>> I don't think anyone disagrees with these points. But a role does >>> NOT imply a central place . . . . >> >> I understand that you think of the term "a role" as being >> all-inclusive, but I don't think it is. Even asserting that there is >> "a role" is making some assumptions. I'll try to explain more >> clearly with some diagrams. >> >> Slide1 (attached) views the top of the triangle as "a role". It >> clearly allows any publishing/discovery agency (or "registry" or >> whatever you want to call it), but it CLEARLY implies that the >> "Publish" and "Find" actions are using the SAME publish/discovery >> agency. (For this reason, I do not advocate this diagram, and I >> would hope that no one else would either, except as an example of ONE >> style of implementation.) >> >> Slide2 (attached) also views the top of the triangle as "a role". It >> SOMEWHAT implies that the "Publish" and "Find" actions are using the >> same publish/discovery agency. However, the cloud makes the >> implication less conclusive. This ambiguity is important because it >> suggests that we are not constraining what that top part is or does. >> >> Slide3 (attached) shows a rectangle instead of a triangle. It >> doesn't have "a role" at the top, it has TWO roles. It CLEARLY >> suggests that the action of "Publishing" may use an entirely >> different agency than the action of "Finding". For example, the >> Service Provider may "Publish" it's description to a UDDI registry, >> but the Service Requester may "Find" that description in a >> "Jack-Sprat's-Favorite-Web-Services" registry. (Jack Sprat may be >> providing a very valuable service by consolidating WS descriptions >> from many sources.) >> >> Slide4 (attached) has no role at all for the top part. The Service >> Provider, by some means (spam?), has advertised its description >> DIRECTLY to the Service Requester. From an architectural viewpoint, >> there is no third party involved. (Obviously there may be a third >> party involved physically, such as a router, or TCP store-and-forward >> nodes, but that is true of any network connection and is irrelevant >> from an architectural point of view.) >> >> Clearly, our architecture should accommodate all of the above >> scenarios. By drawing the architecture as a triangle with "a role" >> at the top, we ARE making some assumptions that reflect certain >> biases. We can mitigate those assumptions: (a) by drawing the top >> thing as a cloud instead of an atomic node; (b) by carefully >> selecting our labels; and (c) by our accompanying descriptive text. >> All three of these techniques are important to use. >> >>> No one to my knowledge is advocating an exclusive, centralized model >>> for discovery. . . . >> >> It is true that nobody has advocated a PARTICULAR or EXCLUSIVE >> centralized model, but that wasn't the issue. >> >> Some have advocated the use of the word "registry" or "registries" to >> refer to the top cloud. And CLEARLY, for many or most people, the >> word "registry" suggests a central or common "meeting place", whether >> it is implemented in a centralized or distributed (gnutella) fashion, >> and whether there is only one or more than one. >> >> We CAN talk about the action of "publishing", and the action of >> "finding". But unless we know what mechanisms they use, there is >> virtually nothing we can say about the top cloud in the diagrams. We >> cannot even assume that the "Publish" and "Find" actions are >> interacting with the same entity. >> >>> . . . this inane debate . . . . >> >> Well, the debate really isn't about arbitrary terms. It is about the >> underlying architectural assumptions that are implied by our terms >> and diagrams. It is clear that some people have made some >> assumptions while others have made others, and we DO need to come to >> agreement about those assumptions. >> >> >> -- >> David Booth >> W3C Fellow / Hewlett-Packard >> Telephone: +1.617.253.1273 >> <Slide1.PNG><Slide2.PNG><Slide3.PNG><Slide4.PNG> >
Received on Friday, 4 October 2002 13:57:18 UTC