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RE: Proposed text on 'SOA' (resend)

From: Cutler, Roger (RogerCutler) <RogerCutler@chevrontexaco.com>
Date: Tue, 9 Sep 2003 16:27:07 -0500
Message-ID: <7FCB5A9F010AAE419A79A54B44F3718E026EFBD8@bocnte2k3.boc.chevrontexaco.net>
To: "David Orchard" <dorchard@bea.com>, "Martin Chapman" <martin.chapman@oracle.com>, "Savas Parastatidis" <Savas.Parastatidis@newcastle.ac.uk>, "He, Hao" <Hao.He@thomson.com.au>
Cc: www-ws-arch@w3.org, "Jim Webber" <jim.webber@arjuna.com>

Well said.  I completely agree, right down the line.

-----Original Message-----
From: David Orchard [mailto:dorchard@bea.com] 
Sent: Tuesday, September 09, 2003 4:13 PM
To: 'Martin Chapman'; 'Savas Parastatidis'; 'He, Hao'
Cc: www-ws-arch@w3.org; 'Jim Webber'
Subject: RE: Proposed text on 'SOA' (resend)



When you say "same" web service, do you mean the same type or the same
instance?

I would say the equality function for stateless web service, ie same
type of web service, is a combination of the interface and endpoint
address.  The equality function for stateful web service, ie the
instance, adds on service specific parameters (aka ws addressing
reference properties).

I think the best way to differentiate stateful and stateless web
services is what is used to determine equivalence of the service
identifiers.

I also want to make sure that the web services architecture does not
"value" stateless web services higher than stateful web services.  I
personally think that much of the web is built upon stateful retrievals,
where things like cookie variables are used to determine the service
identifier.  Some will claim that stateless services are necessary to be
higher performance than stateful services, but that is simply
architecturally incorrect.  After much discussion and learning about how
my company builds products and looking at the characteristics of the
typical interactions of web vs web services, I will vehemently argue
against any prevailing wisdom that says stateless is by definition
better than stateful.

Cheers,
Dave

> -----Original Message-----
> From: www-ws-arch-request@w3.org [mailto:www-ws-arch-request@w3.org]On
> Behalf Of Martin Chapman
> Sent: Tuesday, September 09, 2003 12:09 PM
> To: 'Savas Parastatidis'; 'He, Hao'
> Cc: www-ws-arch@w3.org; 'Jim Webber'
> Subject: RE: Proposed text on 'SOA' (resend)
>
>
>
> I mostly agree about your comment below, but I think there is missing 
> one piece that allows "statefulness" to be layered on top.
> In a pure "stateless model"  I (mostly) don't care which web
> service process
> my request. But a necessry precursor to the stateful
> models is the ability to talk to the "same"  web service over
> as series of
> interactions. Thus an identity model is required.
>
> Martin.
>
>
> > -----Original Message-----
> > From: www-ws-arch-request@w3.org [mailto:www-ws-arch-request@w3.org]

> > On Behalf Of Savas Parastatidis
> > Sent: Tuesday, September 09, 2003 11:37 AM
> > To: He, Hao
> > Cc: www-ws-arch@w3.org; Jim Webber
> > Subject: RE: Proposed text on 'SOA' (resend)
> >
> >
> <snip>
> >
> > Regarding statefulness/stateless...
> >
> > I personally see services as stateless entities. A service should be

> > defined with stateleness as a default behaviour. By statelness I 
> > mean that there is nothing in the definition of a service that 
> > allows it to correlate messages it receives or sends. Statefulness 
> > is achieved through additional message correlation mechanisms.
> >
> > If a token was to be sent as part of the message, that doesn't mean 
> > that the service is stateful. Instead, an application-specific 
> > mechanism has been employed to build stateful interactions on top of

> > a stateless architecture (SOA). There is something to be said about 
> > a community-agreed mechanism for achieving this but the fact still 
> > remains that the semantics of a service do not need to change. So, I

> > agree with Bill's comment that this group should provide guidance
> > on how stateful interactions should be achieved in the same
> > manner that the group is talking about transactions,
> > orchestration, etc. However, that does not mean that anything
> > regarding stateful interactions should appear in the
> > explanation of SOA and the definition of a service.
> >
> > Just my 2c.
> >
> > Regards,
> > --
> > Savas Parastatidis
> > http://savas.parastatidis.name
> >
> >
> >
>
>
Received on Tuesday, 9 September 2003 17:28:56 GMT

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