title: Basic schema design for notifications/feeds/requests?
body: <p>I am designing a social network and wanted to know if I am on the right track. I have Notifications, Requests and Live feeds on the site. Similar to what we see on most sites nowadays. To design these, I assume these are NOT separate components rather they all flow out from the same Activity component? </p>
  
  <p>System has a set of say 200 activities possible involving 30 objects. 40 activities may have notifications, 70 may have feeds, 10 may have requests. So I assume these will be part of the activity look up table that is - does the activity have a Feed, Notification, Request as Boolean columns. If yes, then the default text to display for all 3 (Feed, Notification, Request) to the user like "NAME commented on  photo." Another column will be FK to the object look up table to match objects with activities.</p>
  
  <p>So basically I am unsure if these should all be part of the activity look up table only or is there some other design to consider?</p>
  
  <p>One possible use case is like notifications - the system may have 40 available but the user may only optin to 10 of those. So there will be a separate user settings table to hold user defined preferences.</p>