Subject: Re: [core] #184: Add implementation note to 3.5 about careless GETs

From: "core issue tracker" <[email-masked]>
Date: Thu, 01 Mar 2012 16:04:57 -0000

#184: Add implementation note to 3.5 about careless GETs

Comment (by hartke@…):

 At the end of section 3.5, add:

 Implementation note: A client that does not mediate all its requests
 through its cache might inadvertantly cancel an observation relationship
 by sending an unrelated GET to the same resource.  To avoid this, without
 incurring a need for synchronization, such clients can use a different
 source transport address for these unrelated GET requests.

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 Reporter:  cabo@…              |       Owner:  draft-ietf-core-observe@…
     Type:  editorial           |      Status:  new
 Priority:  minor               |   Milestone:
Component:  observe             |     Version:
 Severity:  Active WG Document  |  Resolution:
 Keywords:                      |
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Ticket URL: <http://trac.tools.ietf.org/wg/core/trac/ticket/184#comment:1>
core <http://tools.ietf.org/core/>

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From: "core issue tracker" <[email-masked]>
Date: Fri, 09 Mar 2012 12:15:06 -0000

Changes (by hartke@…):

 * status:  new => closed
 * resolution:   => fixed

Comment:

 Done.

-- 
--------------------------------+----------------------------------------
 Reporter:  cabo@…              |       Owner:  draft-ietf-core-observe@…
     Type:  editorial           |      Status:  closed
 Priority:  minor               |   Milestone:
Component:  observe             |     Version:
 Severity:  Active WG Document  |  Resolution:  fixed
 Keywords:                      |
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Ticket URL: <http://trac.tools.ietf.org/wg/core/trac/ticket/184#comment:2>
core <http://tools.ietf.org/core/>

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From: Salvatore Loreto <[email-masked]>
Date: Fri, 9 Mar 2012 15:44:44 +0200

>   source transport address for these unrelated GET requests.
I fully agree with the second sentence of the above paragraph.
Above the first one I have the following question:
how does a mediation level (e.g. a cache) distinguish an actual cancel 
request
from an inadvertent one

cheers
Salvatore

-- 
Salvatore Loreto
www.sloreto.com

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From: Carsten Bormann <[email-masked]>
Date: Fri, 9 Mar 2012 16:58:49 +0100

On Mar 9, 2012, at 14:44, Salvatore Loreto wrote:

> how does a mediation level (e.g. a cache) distinguish an actual cancel request
> from an inadvertent one

It doesn't.

If a cache has a single client with an observation relationship and that cancels (for a reason or inadvertently), the cache no longer has a client with an observation relationship.  It depends on the cache's configuration whether that also causes the cache to cancel its observation relationship with upstream.

If it has two, and one is canceled, it still has one.  No need to do anything towards upstream.

All this is true independent of whether the cache is an actual intermediary sitting in the network or a local software layer.

Grüße, Carsten