Subject: [Simple] Re: draft-ietf-simple-xcap-package-03 How to indicate that a document is deleted or a new document is added during a subscription

From: Jonathan Rosenberg <[email-masked]>
Date: Sat, 19 Feb 2005 10:04:26 -0500

I was just now combing through the archives in the process of updating 
the data model, and noticed this mail that I never responded to. My 
apologies. Answers inline.

Anders Lindgren C (HF/EAB) wrote:

> Hello all; In the draft draft-ietf-simple-xcap-package-03 I find it
> hard to see if and how it is possible to indicate that:
> 
> 1) A document has been added to a watched user's tree during the
> duration of the subscription.

This is a gap in the specification. Good catch! Thanks for finding it.

I would propose the following solution.

The <document> element have an attribute called state, which can have a 
value of "existing" or "deleted". When a document is added, an xcap-diff 
would get sent with a value of "existing" and the <add> patch elements 
would basically contain the entire document.

Modifications to the document would result in <document> elements with 
either no state attribute, else state with a value of "existing" (that 
is, the default is existing). If the document is deleted, the <document> 
element would have a state of deleted, and there would be no patch 
operations.

It would be an error to send an xcap-diff with a <document 
state="deleted"> with patch operations.

The recipient of xcap-diff knows a doc is added if the diff has a 
<document> element with a document locator that it doesnt know about. I 
prefer this approach to having an explicit "added" state, as it reduces 
the number of error cases.

Does this seem reasonable?

> 
> 2) A document has been deleted from a watched user's tree during the
> duration of the subscription.

See above.

> 
> Is a "deteted document" and an "added document" element missing or
> 
> is it that every Notify also SHALL contain every unchanged existing
> documents with New Etag=previous Etag  and that the Subscriber can at
> every Notify shall check the last received Notify to see if the
> document baseline has been changed. A  Notify will also be send as
> soon as a document has been added deleted with all existing or
> 
> does the draft contain a solution that I have missed?

It would be wasteful to have to send a <document> for every document 
covered by the subscription, just to figure out when something is 
deleted. The problem you outline is a gap in the spec.

Thanks,
Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                   600 Lanidex Plaza
Director, Service Provider VoIP Architecture   Parsippany, NJ 07054-2711
Cisco Systems
[email-masked]                              FAX:   (973) 952-5050
http://www.jdrosen.net                         PHONE: (973) 952-5000
http://www.cisco.com

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