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Re: ACTION-294 Ashok to open a CR issue with text to define "collection"

From: Fabian Ritzmann <Fabian.Ritzmann@Sun.COM>
Date: Fri, 04 May 2007 15:48:47 +0300
To: Ashok Malhotra <ashok.malhotra@oracle.com>
Cc: "public-ws-policy@w3.org" <public-ws-policy@w3.org>
Message-id: <463B2BAF.1090802@Sun.COM>

To point 3, at least when it comes to WSDL, I don't think duplicate 
subjects (i.e. WSDL elements with the same fully qualified name) make 
sense. They certainly are not ordered.

Regarding points 1 and 2, wouldn't it be an implementation decision if 
duplicates are maintained (bag) or discarded/collapsed (set)? I can't 
find any necessity to keep duplicates.


Ashok Malhotra wrote:
> My point was that the word ‘collection’ in Computer Science is used as 
> a generic term to cover several types of collections.
> See definition from Wikipedia below. Thus, it would be better to be 
> more precise about the exact type of collection we use in WS-Policy:
> In _object-oriented programming_ 
> <http://en.wikipedia.org/wiki/Object-oriented_programming>, a* 
> collection class* is any _class_ 
> <http://en.wikipedia.org/wiki/Class_%28computer_science%29> that is 
> capable of storing other _objects_ 
> <http://en.wikipedia.org/wiki/Object_%28computer_science%29>. 
> Collection classes usually implement some kind of _data structure_ 
> <http://en.wikipedia.org/wiki/Data_structure>, such as a _list_ 
> <http://en.wikipedia.org/wiki/List_%28computing%29>, _map_ 
> <http://en.wikipedia.org/wiki/Associative_array>, _set_ 
> <http://en.wikipedia.org/wiki/Set_%28computer_science%29>, _array_ 
> <http://en.wikipedia.org/wiki/Array>, or _tree_ 
> <http://en.wikipedia.org/wiki/Tree_%28data_structure%29>. A collection 
> class is usually able to store an arbitrary number of data items, i.e. 
> the size of the collection is adjusted automatically.
> In the framework document we use ‘collection’ in three contexts:
> 1. “A _policy_ <http://www.w3.org/TR/2007/CR-ws-policy-20070330/> is a 
> collection of policy alternatives.” Since alternatives can be 
> identical and there is no order between them, a policy is a bag of 
> alternatives.
> 2. “A _policy alternative_ 
> <http://www.w3.org/TR/2007/CR-ws-policy-20070330/> is a collection of 
> policy assertions.” Here, again, the assertions in an alternative can 
> be duplicates and are unordered, so bag seems to be the correct term.
> 3. “A _policy scope_ 
> <http://www.w3.org/TR/2007/CR-ws-policy-20070330/> is a collection of 
> policy subjects to which a policy applies.” Here I am not sure. Can 
> there be duplicate subjects in a policy scope? Aren’t policy subjects 
> ordered?
> If the policy subjects in a policy scope can be duplicates and are not 
> ordered then all uses of ‘collection’ mean ‘bag’ and we can add a 
> definition such as “In this document the word ‘collection’ refers to 
> what is known in the literature as ‘bag’. But I thought we should 
> clarify point 3 first.
> All the best, Ashok
Received on Friday, 4 May 2007 12:48:57 UTC

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