Some questions from last week:

1) In publish/subscribe, do interaction partners need to know each other?
   Do they need to be actively participating in the interaction at the same time?

2) Does Sienna give strict timeliness guarantees?  Does it scale?
   Does it handle complex data types?

3) What events cause the subscription table at a Sienna server updated?

4) How would you characterize email (ie SMTP)
   persistent asynchronous?
   persistent synchronous?
   transient asynchronous?
   transient synchronous?
   call return?
   publish/subscribe?