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RE: The meaning of life and death

From: Yaron Goland <yarong@microsoft.com>
Date: Wed, 22 Jul 1998 13:00:02 -0700
Message-ID: <3FF8121C9B6DD111812100805F31FC0D029716DC@red-msg-59.dns.microsoft.com>
To: "'Babich, Alan'" <ABabich@filenet.com>, "'Jim Davis'" <jdavis@parc.xerox.com>, w3c-dist-auth@w3.org
In the case of live properties it is up to the property's definition to
decide what transformations are allowed. So one could imagine having a
property which states that if you submit a number in scientific notation
then it MUST be returned in scientific notation. There is no general rule,
it is up to each live property to decide what its behavior is.


> -----Original Message-----
> From: Babich, Alan [mailto:ABabich@filenet.com]
> Sent: Wednesday, July 22, 1998 12:21 PM
> To: 'Jim Davis'; w3c-dist-auth@w3.org
> Subject: RE: The meaning of life and death
> > 1. What is life?
> The spec. says (section 3.1): "A live property has its syntax
> and semantics enforced by the server. Live properties include
> cases where a) the value of a property is read-only, maintained
> by the server, and b) the value of the property is maintained
> by the client, but the server performs syntax checking on
> submitted values." This seems clear to me now.
> For live (a) properties, getcontentlength is a perfect
> example. It is readonly, and is maintained by the server.
> The client doesn't have to make any effort to maintain
> the value -- the server maintains it automatically.
> For live (b) properties, the notion of the domain of values 
> of the property is absolutely necessary: The DOMAIN OF VALUES 
> of a property is what largely captures its semantics 
> (examples: zip code, street address, house number, Title, etc.).
> Domains are subsets of values of some datatype. (For example,
> zip codes are a finite subset of the integers.)
> In order to enforce the SYNTAX of the string-ized 
> representation of the value in the protocol, the server 
> MUST know the DATATYPE. In order to enforce the SEMANTICS, 
> in general the server MUST know the DOMAIN. Structures
> are a denumerably infinite set of datatypes. Servers
> are free to have structures as values of properties,
> expressed as XML markup or any other way, with or without
> defaults for some fields, etc. There are no surprises for live (b).
> What is death?
> All dead properties must be strings that are stored by the server
> and returned VERBATIM. They logically can not be anything else,
> because the server is guaranteed to be ignorant of what concept
> the client has in mind for the datatype and domain,
> and the server must return the value verbatim. Dead properties 
> really weren't even worth calling special attention to, IMHO. 
> It would have been better to say that string property values 
> are stored and returned verbatim, but that's normally assumed
> anyway.
> > 2. What is enforcement?
> >  
> > Clearly, rejecting a PROPPATCH with 409 Conflict is one form 
> > of enforcement. 
> Yes.
> > But is this the only kind of enforcement?
> The possibility of the server quietly not storing the value
> is a very poor design, IMHO, and I propose that we reject that 
> alternative by not implementing it.
> > I don't see anyplace in the spec that says that the value 
> > returned by a
> > PROPFIND must be byte for byte identical with that deposited 
> For dead properties, the spec. says that value MUST be returned
> VERBATIM. For live properties, the spec. is quiet. IMHO it
> is perfectly reasonable for the value returned for a live (b)
> property to be equivalent, based upon understanding of
> the datatype and domain of the property. For example, strings 
> would obviously have to come back exactly. But a floating point 
> number could come back in scientific notation (e.g., 1.31E+01)
> or fixed point notation (e.g., 13.1), and that would be 
> fine IMHO.
> Alan Babich
Received on Wednesday, 22 July 1998 15:59:46 UTC

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