Policy intent examples for eventing

[Anish Karmarkar <Anish.Karmarkar@oracle.com>]

I (along with 'et alia') had an action to start a thread on end-to-end 
policy examples for the eventing space. I'm hoping this email will start 
the discussion. The examples are not exhaustive. This is just an attempt 
to get the discussion going.

1) confidentiality
Confidentiality is on the message and therefore needs to be maintained 
over all links in the message path. In the case of a 
broadcast/peer-to-peer model, there is only one hop (at least at a 
higher level) between a producer and a consumer. But in a broker or 
hub-and-spoke scenario there are multiple hops. Confidentiality will 
have to preserved over all hops. One way to do this is to require 
confidentiality on the SCA channel and require intent matching on all 
producers and consumers.

2) authentication
There are more than one possible usecases here. It may be that the 
events are sensitive in nature and therefore all producers and consumers 
have to be authenticated (say payroll related events). In this case, the 
previous model of intents on the channel and requiring intent matching 
on all producers/consumers will work. But there is another usecase where 
producers are required to be authenticated but consumers are not. For 
example, you want everyone to get earthquake reports, but allow only 
authenticated producers to generate one. One way would be to use 
multiple bindings on the channel (via extensions) and get producers to 
use the binding that requires authentication, whereas consumers use an 
unauthenticated binding. Another way is to do some kind of channel 
forwarding/mirroring (behind the scenes) and have two channels, one for 
producers, one for consumers. Another possibility is to allow one to 
specify whether intents specified on channels are applicable to 
producers or consumers or both. I'm sure there are more.


-Anish
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