On 9/4/07 12:56 PM, Eric Burger wrote:
However, one thing we need to be mindful of are side effects. MIME body parts can make external references. Those external references (to http/https URI's) may hit application servers. Those application servers may do something based on the receipt of the URI. It could be as simple as recording the fact the body part was read (like a web beacon), or it could be as complex as changing application state.
We can't count on such side-effects being activated -- whether external references are acted upon is a policy choice that the client can make unilaterally. For example, to prevent beacon-tracking of emails, many email clients allow suppression of embedded remote images.
What do people think of this? Do we say that SIP engines are opportunistic, and the side effect MUST happen if the body gets used, buy the side effect MAY happen if the body does not get used? That would be my vote, as the alternative, that all side effects (external references get resolved) happen puts a pretty big burden on User Agents.
I think that such a MUST is overly-restrictive. For security and privacy reasons, I believe it is important for clients to be able to make policy-related decisions regarding external references, even in the case that the body containing such references is otherwise used by the client.
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