- From: Mark Potts <mark.potts@talkingblocks.com>
- Date: Wed, 20 Mar 2002 15:51:58 -0800
- To: "'Hugo Haas'" <hugo@w3.org>, <www-ws-arch@w3.org>
Hugo... Forgive me if some of this has been covered, I couldn't see that it had though. Not sure if I agree with the definition of "predictable evolvable" and its correlation to Stability. In the Architecture who is responsible for knowing the consumers of a service and managing the notification of detrimental change? I would not say that notifying a consumer at the time of invocation that the service has changed would not constitute a stable system! Even notifying them prior depends on the time you give them to react. This leads me to believe someone else is responsible for managing this task. I am presuming we are not advocating the service itself tracks its consumers, such that it can notify them of detrimental change. So that means a third party outside the producer and consumer. If this is true then I would say "predictably evolvable" should include the ability of a Web Service to define its compatibility ( i.e. its WSDL and the relationship it has to other WSDL ), such that the third party can manage that relationship and make services "predictable evolvable" not just from a consumers perspective but a producers perspective also and thus more stable. The case we need to be sure of is changes in WSDL that make the new definition non-compatible with the last definition. In the case of WSDL extending its port types, would I need to notify? or simply manage the consumption in terms of service definitions. Regards, Mark Potts > -----Original Message----- > From: www-ws-arch-request@w3.org [mailto:www-ws-arch-request@w3.org]On > Behalf Of Hugo Haas > Sent: Wednesday, March 20, 2002 2:56 PM > To: www-ws-arch@w3.org > Subject: Re: D-AG0007.1- defining reliable and stable WS [was RE: > Status: D-A G0007 - reliable, stable, predictable evolution] > > > * Hugo Haas <hugo@w3.org> [2002-03-20 17:29-0500] > > I am cathing up on lots of threads, no I will ask the following: has > > "reliability, stability, and predictable evolution of [..] the > > services themselves" been discussed? > > I am answering my own question: > > http://lists.w3.org/Archives/Public/www-ws-arch/2002Mar/0309.html > > and following up on Suresh's email: > > * Damodaran, Suresh <Suresh_Damodaran@stercomm.com> > [2002-03-18 16:58-0600] > > I am considering the goal > > "reliable, stable, and predictably evolvable web services" > as D-AG0007.1 > > till we get a formal number for it. I volunteer to be the > champion of this > > goal > > (unless somebody else (do you want to be?) wants it, that is:-) > [..] > > Stable - A WS is stable as long as any change in WS > implementation conforms > > to the independent specification (say WSDL) of the WS for > all potential > > users. Note that the specification of WSDL could change, > and as long as all > > users/service requesters are > > "aware"/notified of it. > > This is where the "predictably evolvable" Web services meets > stability, I think... > > [..] > > -----Original Message----- > > From: Hao He [mailto:Hao.He@thomson.com.au] > > Sent: Thursday, March 14, 2002 6:35 PM > > To: Damodaran, Suresh; Hao He; www-ws-arch@w3.org > > Subject: RE: Status: D-AG0007 - reliable, stable, > predictable evolution > > > > > > hi, Damodaran, > > > > I would regard the stability of a web service as the > stability of the > > identifier (the URI) and the logic concepts associated with > it. For example, > > if a company sells car at http://xys.com/buy/car, one > expects the URI to be > > stable so one can bookmark this URI and one expect to buy a > car not a book. > > > > <sd> > > Would you not consider this a "reliability of URI" than a > stability issue > > in light of the discussion above? > > </sd> > > > > > > The second part is more tricky. How about: "the > architecture should enable > > a web service to reveal its attributes to its consumers and verified > > independently by its consumers or third parties so a > selection mechanism can > > be enforced. "? > > > > > > Note the attributes can be more than just those needed in > order to discover > > the web service. > > <sd> > > We need a new goal for this (and a champion). Sounds fine to me. > > > > may be we need 2 - one for "discovery" and another for > "criteria based > > selection?" > > </sd> > > ... and where it relates to the dependency on certain versions as I > was talking about in my email[1]. > > To me, the stability aspect is that the service will have a interface > and behavior advertised for a particular version, which is I think in > accordance with Suresh's definition. > > The predictability of evolution aspect hints that there is a way to > say: > - that one wants to use a particular version. > - that a change in behavior and/or interface, in other words a change > of version, will be signaled one way or the other (a new URI for the > new version comes to mind, for example). This is what Suresh was > refering to with "Note that the specification of WSDL could change, > and as long as all users/service requesters are "aware"/notified of > it." > > I therefore support such a goal. > > Regards, > > Hugo > > 1. http://lists.w3.org/Archives/Public/www-ws-arch/2002Mar/0349.html > -- > Hugo Haas - W3C > mailto:hugo@w3.org - http://www.w3.org/People/Hugo/ - > tel:+1-617-452-2092 > > >
Received on Wednesday, 20 March 2002 18:52:27 UTC