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Encoding issue: missing elements same as nils?

From: Jacek Kopecky <jacek@systinet.com>
Date: Sat, 5 Jan 2002 20:40:55 +0100 (CET)
To: <xml-dist-app@w3.org>
Message-ID: <Pine.LNX.4.33.0201052013040.2787-100000@mail.idoox.com>
 Hi, I was tasked by the ETF to formulate and send in the 
following issue:
 
 In SOAP Encoding in structures and in arrays, accessors can be 
omitted.
 The current WD says:
 (section 4.2, rule #9) "A NULL value or a default value MAY be
represented by omission of the accessor element. A NULL value MAY
also be indicated by an accessor element containing the attribute
xsi:nil with value '1 or true' [...]"
 (section 4.5) "An omitted accessor element implies either a
default value or that no value is known. The specifics depend on
the accessor, method, and its context."
 This text applies to both arrays and structs.

 The issue is: what does an omitted accessor really mean?
 There seem to be two options: 
 a) a NULL value equivalent to the situation of the accessor 
being present with xsi:nil set to true,
 b) a default value defined by the application.

 All other apparent options - null-or-default, 
complete-nothing-at-all etc. - are IMHO equivalent with b).

 Reasons for the two options, as I gather, are the following:

 pro a)	1: default or no values are usually represented by the 
language's NULL, which is not a first-class value.
	2: simple handling 

 pro b)	1: able to distinguish between an explicit NULL and the 
default/unknown value.

 Best regards

                   Jacek Kopecky

                   Senior Architect, Systinet (formerly Idoox)
                   http://www.systinet.com/
Received on Saturday, 5 January 2002 14:40:56 GMT

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