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RE: Visibility (was Re: Introducing the Service Oriented Architec tural style, and it's constraints and properties.

From: David Orchard <dorchard@bea.com>
Date: Mon, 24 Feb 2003 22:51:52 -0800
To: "'Champion, Mike'" <Mike.Champion@SoftwareAG-USA.com>, <www-ws-arch@w3.org>
Message-ID: <000501c2dc9a$6148a3e0$550ba8c0@beasys.com>

Mike, I agree with you.  I believe that the statement should read "can be
less simple to configure and degrade network and perceived performance".
This focuses the issue on simplicity and performance impacts of visibility.
As an example of the XPath usage, instead of cache "GET on URI X", it's
cache on "XYZ on URI X with XPath Foo=true".  Obviously this won't work if
the message is encrypted.  I think the trade-off is clear.  Caching of just
a URI is simpler than with XPath, but certainly not insurmountable.

Cheers,
Dave

> -----Original Message-----
> From: www-ws-arch-request@w3.org [mailto:www-ws-arch-request@w3.org]On
> Behalf Of Champion, Mike
> Sent: Wednesday, February 19, 2003 3:47 PM
> To: www-ws-arch@w3.org
> Subject: RE: Visibility (was Re: Introducing the Service Oriented
> Architec tural style, and it's constraints and properties.
>
>
>
> >
> >
> > -----Original Message-----
> > From: Mark Baker [mailto:distobj@acm.org]
> > Sent: Wednesday, February 19, 2003 6:26 PM
> > To: dorchard@bea
> > Cc: www-ws-arch@w3.org
> >
>
> > On Wed, Feb 12, 2003 at 10:01:31PM -0800, dorchard@bea wrote:
> > > The RESTful SOA has the advantage better visibility, as the
> > firewall
> > > can simply examine the generic interface to determine the
> > action being
> > > performed.   Intermediaries, such as HTTP routers or
> > caches, can simply look
> > > at the method.  An example is that a cache can look at the
> > GET and the
> > > identifier, and return a cached representation.  This is
> much more
> > > difficult if the method is in arbitrary places in the POST.
> > > Re-usability can be higher as the service may be available
> > on the Web
> > > as a URI may be transferable.
> >
> > I agree with him completely.
>
> The only part I disagree with is "much" in "much more
> difficult."   Sure
> it's easier to write a firewall that only looks at HTTP
> headers and not the
> SOAP content of a message, but it's do-able to build XML/SOAP-aware
> firewalls, it's being done, and this is practical mainly
> because XML and
> SOAP provide a framework that is flexible enough to be useful for most
> anything but "visible" via standard XML toolkits.
>
> Obviously this extends to routers as well; SOAP-aware routers
> would work
> with any protocol -- FTP, SMTP, BEEP, TCP/IP, MQ -- as well
> as HTTP.  XML
> standards (e.g. Xpath) allow routing based on message content
> as well as the
> headers.  I think of this as a feature to be valued, e.g. in
> spam filters.
>
> So again, I agree that "visibility" is an important property, but what
> powers it is *standards*, not just HTTP.
>
>
>
Received on Tuesday, 25 February 2003 01:54:48 GMT

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