Subject: [core] Caching of responses

From: Jim Schaad <[email-masked]>
Date: Wed, 30 Nov 2016 22:52:12 -0800

In the process of talking about the OSCOAP drafts with people at the Seoul
IETF, I finally managed to get my understanding of the caching problem that
I see into a formulation that can be understood by other people.

When you look at caching, there are two different types that can be thought
about:

1.  I am caching a value that can be used by anybody who asks for the same
answer.  This is the classical type of caching that occurs on the internet
today and is how things such as DNS work.

2. I am caching a value that can only be used by a specific person, but I am
doing so in order to deal with the fact that the network is unreliable and
by doing so I can a) decrease the response time in the even the packet is
lost between me and the asker and b) can generally increase the reliability
of the network between me and the responder.  Generally, this type of
caching would require a combination of asker address/port and information
from the request.

CoAP currently supports the first and not the second.  When security is
added to messages, I believe that the second type of caching may become
important as well since the first set of caching would hopefully approach
zero as we add more and more security to messages. 

Am I way out in left field or does this make sense?

Jim