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RE: Proposed replacement text for Section 1.6

From: Champion, Mike <Mike.Champion@SoftwareAG-USA.com>
Date: Mon, 12 Jan 2004 11:19:59 -0500
Message-ID: <BDD579D96530CA4BAAAD5D9549BDE77901457AE6@resmsg01.sagus.com>
To: "'www-ws-arch@w3.org '" <www-ws-arch@w3.org>


> -----Original Message-----
> From: He, Hao [mailto:Hao.He@thomson.com.au] 
> Sent: Sunday, January 11, 2004 11:23 PM
> To: 'Champion, Mike'; 'www-ws-arch@w3.org '
> Subject: RE: Proposed replacement text for Section 1.6
> 1. The architectural goal of SOA (and WS in general) is to 
> "achieve loose-coupling between interacting software agents 
> in order to preserve the benefits of reusability, 
> extensibility and simplicity."

I don't think loose coupling is a goal; it's the result of good application
of SOA, Web services, etc.  My "goal" is to build a system that works
simply, reliably, and accomodates change.  "Loose coupling" in a software
engineering term to describe an architectural arrangement that is purported
to help achieve these goals.  I realize that these are fine distinctions and
don't want to argue about them, and would accept your proposal if others
like it.

> 2. Two main architectural constraints of SOA: 1) A small set 
> of simple and ubiquitous interfaces to all participating 
> software agents. 2) Descriptive messages delivered through 
> the interfaces.  

OK.  I do see these as the key factors that distinguish SOAs from other
similar architectural patterns.  Calling them "constraints" is fine with me.
> I, personally, would also add extensibility as part of the 
> constraints but Dave O would argue it is just a best practise 
> (however, he believes that extensibility is important and has 
> written a number of articles on it). 

I'm with Dave Orchard on this.  Extensibility is important, but it's a
consequence of doing things according to SOA constraints and best practices,
not a constraint in and of itself.
> As to the relationships among the terms  "distributed 
> system", "service oriented architecture," and  "web service", 
> I believe there are just two main kinds, those based on OO 
> and those based on SOA. The confusion comes when one tries to 
> do "distributed objects" using Web services. 

Well (not to re-stock the ur-troutpond) you CAN do distributed objects with
web services technologies, and I more or less insist that we acknowledge
that.  To deny it would be to say that the first generation of Web services
tools is useless.  I think even the most fervent RESTifarians would admit
that they have their uses in secure, reliable, fast domains (such as a
corporate intranet). The issue has always been whether the the distributed
object approach scales to the cross-enterprise or Internet level, and if it
does whether CORBA is a better platform to build on than the WS-* stuff.  

Roger seems to disagree, and if we were trying to *prescribe* what the
industry should do rather than *describe* what it actually does, I wouldn't
have a problem with making a stronger statement about the folly of using WS
technologies to implement distributed objects outside the firewall.  But I
don't think Web services as we define them, with SOAP, WSDL, and XML as
necessary attributes, implies either an SOA or distributed object
archictural pattern.
Received on Monday, 12 January 2004 11:20:10 UTC

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