>> 1. Introduction
>> A carefully developed mechanism for the communication of information
>> about changes to Internet resources offers the potential for other
>> functions above and beyond invalidation of cached objects. More
>> general applications for this mechanism might include automated
>> tracking of changes to related groups of resources through 'channel'
>> subscriptions for real-time 'mirroring' of collections of resources,
>> and the sharing of information about cached objects between
>> intermediaries from different vendors. Resource updates may also be
>> an appropriate way of informing systems which generate content
>> dynamically that the underlying data which they manipulate (e.g. to
>> produce HTML pages) has changed.
>> TH> If you don't want this to include notification from OPES
>> TH> about transformations, you might want to rule it out of scope here,
>> TH> just to keep the lines clear later
It should be left up to the intermediaries, whether OPES based are not, to
decide if they need to generate a validation request. If the intermediary
performs the transformation and then cache the result it most likely won't
send a validation request, unless it keeps state about the original content.
But if the transformation needs to occur on the original cached object the
intermediary might decide to generate a validation request.