Alex,
both examples look good to me. Minor comment inline.
The above concerns call for making notification optional. The OPES
architecture allows for an efficient and meaningful notification
protocol to be implemented in certain OPES environments. For
example, an OPES callout server attached to a gateway or firewall may
scan outgoing traffic for signs of worm or virus activity and notify
a local Intrusion Detection System (IDS) of potentially compromised
hosts inside the network. Such notifications may use OPES tracing
information to pinpoint the infected host (which could be another
OPES entity).
Although I believe to understand the intent of using the term "host"
here, I'm wondering wether it might be easier to understand if we talk
about a "server" in this example. I had to read the example twice to
understand that the "host" you're talking about is a content source
rather than the content consumer. But it might just be me :)
Another environment where efficient and meaningful notification using
OPES tracing is possible are Content Delivery Networks (CDNs). A CDN
node may use multiple content adaptation services to customize
generic content supplied by the content producer (a web site). For
example, the node may insert advertisements for client-local events
or services. The node itself may not understand specifics of the ad
insertion algorithm implemented in OPES callout servers. However, it
may use OPES trace to notify content producer about the number of
certain advertisements inserted (i.e., the number of "impressions"
delivered to the customer) or even the number of ad "clicks" the
customer made (e.g., if the node hosts content linked from the ads).
Note that OPES services may not have enough information to contact
the content producer directly in this case.
The last sentecne could be explained a little more (e.g. what
information might be missing etc.).
Thanks,
Markus