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Francis Norton wrote:
>
> Paul Prescod wrote:
> >
> > Today I step through some Expedia forms to buy an airline ticket, or
> > to buy a book from Amazon. Tomorrow I write a Python program to
> > step through for me. It demonstrably works, even with plain old
> > HTML. I know it works because I do it!
> >
> And how many hours does it take to do it? And how fragile is it, because
> you're reading something which is meant to be read by humans, not programs?
You're combining two unrelated conversations.
Len said that the promises of Web Services are unachievable. Computers
from various companies cannot use web infrastructure to communicate on
business issues. I merely provided an existence proof. I didn't say it
was the best way to do it.
> Or if you are talking XML, how much time will you spend agreeing your
> own little XML protocol with Expedia or Amazon?
Obviously none. Expedia and Amazon will supply an XML Schema.
> .... Will you send your query
> as GET parameters and force the server to institute lots of state
> management so you can build the query up call by call rather than
> sending an entire XML query in one block? Or if you use POST, what CGI
> variable will you use to hold the query block? Or will you just send one
> naked XML block? How will they document what elements they expect to
> receive and send?
Some combination of XML Schema, RELAX or Schema.
> Why not get productive, do it the XML way? Why not write an XML grammar
> which answers all these questions, and an XML protocol to implement the
> transport? Why not call them WSDL and SOAP?
WSDL: Unfortunately it leaves all of the important questions unanswered.
Like...when I submit information how do I get it back again? How do I
refer another web service to the information I've submitted?
SOAP: So it's an XML protocol. Do the angle brackets make it magically
better?
> I can "Add Web Reference" in Visual Studio in about a minute. Leave out
> the obvious assigment statements to and from my query and result
> structures, and it takes me two lines of code to do a synchronous WS
> call, three to do it async. And I'm sure the Java guys aren't far behind.
Great. And now you've got GetStockQuote. I can also do three lines to do
it WITHOUT SOAP and WSDL but I haven't paid hundreds of dollars for the
Visual development environment and I'm not dealing with SOAP 0.9 versus
1.0 versus 1.1 versus 1.2 interoperability issues. And I'm not a year
ahead of the WSDL standard. And I'm compatible with a much broader range
of tools, both commercial and free.
And when you send information into this service, how do you get it it
out again? How do you communicate to some other service how THAT SERVICE
would get the information out. You own the information. You sent it into
the web service. It transformed it or packaged it and stored it. Now how
do you share the information with other web services? Before you answer,
think how you would do it in a programming language. A function
manipulates a structured object with identity. How do you share that
object with other code?
Now think how you would do it on the Web. Somebody points you at a
mutable object like a discussion forum. How do you share that object
with someone else?
Now how do you do it in SOAP/WSDL?
> Some of it's a bit new and rough, but no-one has yet persuaded me that
> there are any show-stopping flaws in it.
An inability to reuse information by reference strikes me as
show-stopping.
> I really don't understand what you're offering as an alternative to WS.
I am totally in favor of Web Services:
http://www.xml.com/pub/a/2002/02/06/rest.html
Paul Prescod
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