Instagram Data Model

post:
	photo or video
	[description]
	time posted
	[expires]
	category
	owner? ... is a user
	nlikes
users: 
	username
	real name
	password
	[profile pic]
activity:
	who did it ... is a user
	what they did
	timestamp
comment:
	user
	post
	text
message:
	text
	timestamp
group:
	name

user did activity
user member-of group
user follows user
user views post
user likes post
user owns post

user sent-by message received-by user
user sent-by gmessage received-by group