RE: Summing up on visibility(?) (really, I mean it this time 8-)

+1!

Christopher Ferris
Architect, Emerging e-business Industry Architecture
email: chrisfer@us.ibm.com
phone: +1 508 234 3624

Mike Champion wrote on 01/10/2003 12:34:00 PM:

> 
> 
> 
> > -----Original Message-----
> > From: Mark Baker [mailto:distobj@acm.org]
> > Sent: Friday, January 10, 2003 11:19 AM
> > To: Miles Sabin
> > Cc: www-ws-arch@w3.org
> > Subject: Re: Summing up on visibility(?) (really, I mean it this time
> > 8-)
> > 
> > 
> >
> > 
> > "The trade-off, though, is that a uniform interface degrades 
> > efficiency, since information is transferred in a standardized form 
> > rather than one which is specific to an application's needs."
> 
> I'm thinking more and more that this is the starting point for *all* web
> services and not a differentiator between REST and SOAP/WSDL.  I'm 
further
> inclined to say that this discussion has helped clarify how one can move
> toward this by either making the information needed by applications 
other
> than the intended one (e.g. intermediaries) available in at least two 
ways:
> make the message content opaque and put the needed information in the
> protocol headers (HTTP is particularly powerful in this respect), and/or 
to
> make the message content "visible" using XML and related standards,
> especially SOAP and its header extensibility model, WSDL to describe the
> contents of the message body in a machine-friendly way, and numerous
> emerging standard SOAP headers to support encryption, authentication,
> signing, routing and reliable messaging across protocols and 
intermediaries,
> choreography of multi-part messages, etc. etc. etc. 
> 
> For whatever it's worth, this discussion has deepened my understanding 
of
> the traditional Web intermediary model based on ports and HTTP header
> information, but it has INCREASED my appreciation for the value that XML 
and
> SOAP add to that.  Just as the synergy of URIs, HTTP, and HTML created a 
Web
> that is much more than the sum of its parts, the Web + XML have 
synergies
> that are just becoming apparent ... and go far beyond the "XML is just
> another opaque data format" perspective that it seems that REST 
advocates
> prefer. 
> 
> The distributed object model without XML would not work well over the
> internet, I do fully agree. But XML breaks out of the boundaries to 
achieve
> RESTful *objectives* in a way that the REST "dogma" doesn't seem to
> appreciate.  "Visibility" is an important principle, and XML makes data
> visible beyond HTTP's dreams.  Likewise, I'm coming to appreciate the
> uniform interface constraint for *data transfer*: a world of hard-coded 
RPC
> methods in opaque messages would be as problematic as Mark claims, but
> XML-serialized object interchanges can leverage both the uniformity of 
the
> data interchange methods and the specificity of traditional distributed
> object systems.  Whatever the theoretical rough spots here, they seem to 
be
> increasingly overwhelmed by the network effect (e.g. all those people 
who
> understand SOAP, WSDL, XPath, etc. are figuring out pragmatic 
workarounds).
> 
> 
> > It seems that only Walden Matthews and James Snell[1] agreed with my
> > characterization of visibility, of those who spoke up.  Is that enough
> > to get it in to the WSA doc?
> 
> Is there some draft text that doesn't talk about cows or circles that 
you
> suggest we put in?  Where would you suggest putting it? Can you live 
with
> something like my summary above of the value of "visibility" and how
> XML-based technologies complement the HTTP-based technologies? [I didn't
> think so :-) ] 
>