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Re: Background information on GET and XForms (was: GET should be enco uraged...)

From: Paul Prescod <paul@prescod.net>
Date: Sun, 24 Feb 2002 16:39:05 -0800
Message-ID: <3C7987A9.79EDCC48@prescod.net>
To: Chris Lilley <chris@w3.org>, "'www-tag@w3.org'" <www-tag@w3.org>
CC: mdubinko@Cardiff.com
Chris Lilley wrote:
> 
>...
> 
> Yes, people seem worried about it. Personally I don't see the problem.
> The basic processing model of XForms is to create and populate an XML
> instance, which represents the result of filling in the form by
> whatever means, and then to *send that XML instance to a server*.

There are three parts to XForms: "A typical form starts off with a
_purpose_, e.g., data collection. This purpose is realized by creating
an interactive _presentation_ that allows the user to provide the
requisite information. The resulting _data_ is the result of completing
the form."

It makes perfect sense to want to express a purpose in an XForms way,
with an XForms presentation and not use the XML encoding for the data.

> There is a method in HTTP for making requests with message bodies. Its
> PUT. 

That is not what the HTTP specification says. You say that PUT is
different in that it has a body. The HTTP specification says that PUT is
different in its semantics. It is a request for the server to store the
object at the given URI. But google (as an example) does not want to
store your query. It wants to process your query, find a matching
resource and return it to you without modifying the resource at all.

> ... GET is, in fact, PUT with a null message body .... a common
> special case. 

Can you find support for this statement in the HTTP specification? Or
Tim Berners-Lee's Web Axioms? According to the axioms, GET is a very
special method, not a "common special case" of some other method.

>...
> How many XForms implementations are there that expect a legacy
> encoding? I agree its an improvement over current (HTML) practice. I
> don't really agree that GET is superior to PUT - use the right tool
> for the job. If there is no message body, just a retrieval request,
> use GET. 

Agreed.

> ... If there *is* a message body, in other words a transfer of
> information from client to server, then POST is more appropriate.

You make it sound as if the decision to have or not have a message body
is pre-ordained. But that's just a syntax choice. HTML 2.x, 3.x and 4.x
showed that the same data can be sent in the URI or in the message body.
It depends on whether you are *addressing* or *sending information*: the
semantics, not the syntax. But of course query addresses can be quite
complicated to construct (as a Google "advanced search" page shows). So
we need the full power of XForms to help us construct them.

 Paul Prescod
Received on Sunday, 24 February 2002 19:42:29 GMT

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