Re: [xri] Links as atomic packages of optional attributes

[Drummond Reed <drummond.reed@cordance.net>]

Eran, very good point about the child elements that are still needed for trust.

I also like the idea of specifying a choice of either URI or URITemplate in each linking "atom".

I personally have no strong opinion about whether, for 0-or-1 cardinality, it is better to use an attribute or a child element. I leave that to the implementation experts on the list.

Given that we do need to close the attribute-or-element issue, let me turn it into a question: who DOES have strong feelings about whether the 0-or-1 cardinality items should be an attribute or a child element?

=Drummond

On Sat, Sep 26, 2009 at 7:05 PM, Eran Hammer-Lahav <eran@hueniverse.com> wrote:

On the cardinality issue, I am in favor of having:

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0 or 1 Rel

0 or 1 MediaType

0 or 1 of either URI or URITempate

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I don�t think we should separate it to two different link types for URI and URITemplate.

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As for expressing link as an attribute, keep in mind that we still have to support Link child elements for at least the trust element. Which means:

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<Link uri=�� rel=�� mediatype=��>

��������������� <ds:KeyInfo />

</Link>

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I am not sure how much we gain from that and if this is any less confusing than just keeping it all as element (with the new cardinality).

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EHL

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From: drummond.reed@gmail.com [mailto:drummond.reed@gmail.com] On Behalf Of Drummond Reed
Sent: Saturday, September 26, 2009 11:11 AM
To: XRI TC
Subject: [xri] Links as atomic packages of optional attributes

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I had another discussion with John Bradley about Breno�s proposal to move to �atomic� links (where both Rel and URI are zero-or-one cardinality). I agree with the point he was trying to make at the end of Thursday�s call about how helpful it would be to XRD crawlers to know what kind of metadata (if any) was at the other end of a link. But when he and I talked about it we both realized that the MediaType element could be used to convey that information.

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Of course that�s yet another element that could be reduced to zero-or-one cardinality to keep Links as atomic packages. And of course if it�s zero-or-one cardinality, then it too should can an attribute.

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So both John and I found ourselves liking the design of every Link consisting of three optional attributes: Rel, URI, and MediaType, as it would be very clear and easy to process, query, and crawl.

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Do others agree?

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If so, what happens to URITemplate? Is it a fourth optional attribute? Or are should we have two kinds of links: Link (with optional attributes Rel, URI, and MediaType) and LinkTemplate (with optional attributes Rel, URITemplate, and MediaType)?

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=Drummond