Yimin,
the standard example for the ISTag motivation is:
A file has been scanned by an ICAP virus scanner. No virus has been detected
and the ICAP client stores the file in cache.
Next day the virus scanner engine is updated and it may now be able to find a
new virus in the file that has been downloaded the day before.
Changing the ISTag is the way to tell the ICAP client that previous responses
that are cached on the client should not be used any longer.
Both, cached ICAP response and cached HTTP object, are invalid.
Regards
Martin
-----Original Message-----
From: Yimin Chen [mailto:ymchen1106(_at_)yahoo(_dot_)com]
Sent: Thursday, May 29, 2003 3:20 AM
To: ietf-openproxy(_at_)imc(_dot_)org
Subject: Question on ISTag in ICAP protocol
Hi,
I am reading section 4.7 regarding ISTag in ICAP
response. In the section, it mentioned that the change
of ISTag should invalidate all entities generated by a
particular service. Could someone clarify for me
whether this "entities" referring to objects in "ICAP
CACHE" (cache to store ICAP responses), or objects in
"HTTP CACHE" (in the case that the ICAP client is a
HTTP proxy.
Thanks!
Yimin
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