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Fw: Comments about http://www.w3.org/DesignIssues/Architecture#Content : is GET the only idempotent method

From: Tim Berners-Lee <timbl@w3.org>
Date: Sat, 12 Jan 2002 14:27:08 -0500
Message-ID: <015f01c19b9f$283b8820$ac01a8c0@CREST>
To: <www-archive@w3.org>
----- Original Message -----
From: "S. Mike Dierken" <mike@dierken.com>
To: "Tim Berners-Lee" <timbl@w3.org>
Sent: Friday, January 11, 2002 10:33 PM
Subject: Re: Comments about
http://www.w3.org/DesignIssues/Architecture#Content : is GET the only
idempotent method


> Yes - I didn't want to appear to be too nitpicky...
>
> ----- Original Message -----
> From: "Tim Berners-Lee" <timbl@w3.org>
> To: "S. Mike Dierken" <mike@dierken.com>
> Sent: Friday, January 11, 2002 8:46 AM
> Subject: Re: Comments about
> http://www.w3.org/DesignIssues/Architecture#Content : is GET the only
> idempotent method
>
>
> > You only replied to me.  May I forward this to a public archive? Tim
> >
> > ----- Original Message -----
> > From: "S. Mike Dierken" <mike@dierken.com>
> > To: "Tim Berners-Lee" <timbl@w3.org>
> > Sent: Friday, January 11, 2002 2:37 AM
> > Subject: Re: Comments about
> > http://www.w3.org/DesignIssues/Architecture#Content : is GET the only
> > idempotent method
> >
> >
> > > What about HEAD?
> >
> > Good point.  The question s, if you want meta-information about a
> resource,
> > then you have to boostrap yourself somehow even if the metadata is
> avaialble
> > in another document.
> >
> > > Is it even used?
> >
> > Yes, I think so.
> >
> > > Does it/can it return an entity body, or just headers (e.g
> Content-Length,
> > > Content-Type, eTag, Location, etc.)
> >
> > Only headers (I hope)
> >
> > > Not that I'm too concerned about it, but there is a question in my
mind
> > > about whether 'status of cvs document' (from your example) should
always
> > be
> > > an entity-body with uri separate from the document itself, or if its
> okay
> > to
> > > return that as a response header. (probably depends on how much you
like
> > to
> > > deal with compound documents).
> >
> > Oh, if it is small a response header is fine.  Something like the entire
> CVS
> > log
> > in hyeprtext, or a general admin page like http://www.w3.org/,tools
> >
> > > If it's okay to return that extra metadata in a header, then HEAD
might
> be
> > a
> > > viable alternative to a separate uri.
> >
> > Certainly, if we are talking about a small amount of information.
> >
> > > If some metadata like 'status' is a
> > > separate resource, how do different apps coordinate/discover the
> > association
> > > between the two resources. One way would be to return a 'get your
> metadata
> > > here' header in responses (which is not much different than putting
the
> > > value in a header and using HEAD).
> >
> > Yes, that is what I envisage.
> >
> > Content-type: text/html
> > Adminpage:  foo.html,tools
> >
> > > Another would be to put it in the
> > > response entity-body (if it supported links).
> >
> >
> > Agreed.
> > Tim
> >
> > > Mike
> > >
> > > ----- Original Message -----
> > > From: "Tim Berners-Lee" <timbl@w3.org>
> > > To: "Mike Dierken" <mike@dataconcert.com>
> > > Cc: <www-tag@w3.org>
> > > Sent: Thursday, January 10, 2002 5:32 PM
> > > Subject: Re: Comments about
> > > http://www.w3.org/DesignIssues/Architecture#Content : is GET the only
> > > idempotent method
> > >
> > >
> > > > Mike,
> > > >
> > > > In Message-ID:
> > > <2AE31649CF989F4FB354F6D95EB0CE6E4D6745@xmlfmail.xmlfund.com>
> > > > From: Mike Dierken <mike@dataconcert.com>
> > > > Date: Thu, 10 Jan 2002 12:53:06 -0800
> > > > Subject: Comments about
> > http://www.w3.org/DesignIssues/Architecture#Conten
> > > > t : is GET the only idempotent method
> > > >
> > > > you say,
> > > >
> > > > """http://www.w3.org/DesignIssues/Architecture#Content
> > > > "The introduction of any other method apart from GET which is
> idempotent
> > > is
> > > > also incorrect, because the results of such an operation effectively
> > form
> > > a
> > > > separate address space, which violates the universality."
> > > >
> > > > I though that PUT was idempotent - it is okay to do the same PUT
twice
> > > > without bad stuff happening"""
> > > >
> > > > You were right, I was wrong.  I have changed the paragraph to read:
> > > >
> > > > """The introduction of any other method apart from GET which has no
> > > > side-effects and is simply a function of the URI is also incorrect,
> > > because
> > > > the results of such an operation effectively form a separate address
> > > space,
> > > > which violates the universality."""
> > > >
> > > > I have also added:
> > > >
> > > > """(Example:  Instead of defining a new method CVSSTAT to retreive
the
> > > code
> > > > management status of a document, that status should be given a URI
in
> > the
> > > > server's space, and headers used to point the aware client to it.
> > > > Otherwise, we end up with a class of document which contains
> interesting
> > > > informatio but cannot be linked to.)"""
> > > >
> > > > This should make more sense.  I misused the word "idempotent".
> > > >
> > > > Tim BL
> > > >
> > > >
> > > >
> > >
> >
>
Received on Saturday, 12 January 2002 14:27:15 GMT

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