I'm wondering what would be the best way to design a social application where members make activities and follow other member's activities using Google AppEngine.
To be more specific lets assume we have these entities:
- Users who have friends
- Activities which represent actions made by users (lets say each has a string message and a ReferenceProperty to its owner user, or it can use parent association via appengine's key)
The hard part is following your friend's activities, which means aggregating the latest activities from all your friends.
Normally, that would be a join between the Activities table and your friends list but thats not a viable design on appengine as there are no join simulating it will require firing up N queries (where N is number of friends) and then merging in memory - very expensive and will probably exceed request deadline...)
I'm currently thinking of implementing this using inbox queues where creation of a new Activity will fire a background process that will put the new activity's key in the "inbox" of every following user:
- Getting "All the users who follow X" is a possible appengine query
- Not a very expensive batch input into a new "Inbox" entity that basically stores (User, Activity Key) tuples.
I'll be happy to heard thought on this design or alternative suggestions etc.
See Question&Answers more detail:
os 与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
