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

>we can add a definition such as "In this document the word
>'collection' refers to what is known in the literature as 'bag'.

The term "bag" sounds too technical.  On the April 25th WG conference call, Monica and Paul made a proposal [1] to address David Hull's question (scrapping from the minutes):

"The items in a collection in this specification are unordered and may contain duplicates."

It appears that Monica and Paul's suggestion works. From a reader point of view, Monica and Paul's suggestion sounds straight forward and clearly defines the term "collection".

David Hull's question can be addressed by adding the above proposed sentence as the penultimate paragraph to the Notational Conventions section in the Framework [2] and Attachment [3] drafts.

>Can there be duplicate subjects in a policy scope?
>Aren't policy subjects ordered?

Yes. A policy scope is a collection of policy subjects that is unordered and may contain duplicates.

[1] http://www.w3.org/2007/05/02-ws-policy-minutes.html#item10
[2] http://www.w3.org/TR/2007/CR-ws-policy-20070330/#Notational_Conventions
[3] http://www.w3.org/TR/2007/CR-ws-policy-attach-20070330/#NotationalConventions

Regards,

Asir S Vedamuthu
Microsoft Corporation



From: public-ws-policy-request@w3.org [mailto:public-ws-policy-request@w3.org] On Behalf Of Ashok Malhotra
Sent: Friday, May 04, 2007 5:29 AM
To: public-ws-policy@w3.org
Subject: ACTION-294 Ashok to open a CR issue with text to define "collection"


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