<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><span style="orphans: 2; text-align: -webkit-auto; widows: 2;">On Sep 9, 2014, at 4:17 AM, Dave Oran (oran) <<a href="mailto:oran@cisco.com">oran@cisco.com</a>> wrote:</span><br><div><br class="Apple-interchange-newline"><blockquote type="cite">
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<div>On Sep 8, 2014, at 6:21 PM, Yingdi Yu <<a href="mailto:yingdi@cs.ucla.edu">yingdi@cs.ucla.edu</a>> wrote:</div><div>
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<div>On Sep 8, 2014, at 12:58 PM, Dave Oran (oran) <<a href="mailto:oran@cisco.com">oran@cisco.com</a>> wrote:</div>
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<blockquote type="cite">I don’t mean to hijack this thread, but it seems that the architecture needs two cache timers, not one.<br>
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One is an Expiry timer after which the data is no longer considered valid (and hence should not be returned from the cache if an interest arrives)</blockquote>
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<div>I am not sure if it is always possible for a data producer to predict the time when the data will become invalid.
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If not the producer, then who? </div></blockquote><div><br></div><div>In many cases, no one knows. For example, you write an article, do you know when you will find some problem in it and change it?</div><br><blockquote type="cite"><div dir="auto">All data kept outside an application's private (and possibly permanent) store has a validity period, if not shorter then at least no longer than the lifetime of the key that signed it.
</div></blockquote><div><br></div>Yes, it is no longer than the lifetime of the key, but it could be shorter than that. As a producer, can you tell how shorter that could be?<br><br><blockquote type="cite"><div dir="auto"><div>
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<div>Take DNS as an example, the authoritative server may never know when one of the records will be changed.</div>
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Wrong analogy. A DNS Authoritative server is like a repo, a producer is in effect the application that updated the DNS.</div></div></blockquote><br></div><div>Ok, then for the "producer" in your mind, can he predict when his DNS record will be changed? I never know when my own domain's A record will be changed, because my ISP occasionally change my home IP address.</div><div><br></div><div>Yingdi</div><br></body></html>