$ sudo apt-get install Python3.4
$ wget https://pypi.python.org/packages/source/v/virtualenv/virtualenv-1.11.6.tar.gz
$ tar xvf virtualenv-1.11.6.tar.gz
$ python3 virtualenv-1.11.6/virtualenv.py redis-test-env
$ source redis-test-env/bin/activate
(redis-test-env) $ pip install redis
   

$ source redis-py-env/bin/activate
(redis-py-env) $ python
Python 3.4.0 (v3.4.0:04f714765c13, Mar 15 2014, 23:02:41) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import redis
>>> local_redis = redis.StrictRedis()
>>> local_redis.dbsize()
    

We'll now use Python to create a small Twitter clone based upon the tutorial, Tutorial: Design and implementation of a simple Twitter clone using PHP and the Redis key-value store

The Redis Key structure for this Twitter Clone

Key	Description	Redis Data Type
next_user_id	user id counter	String
User:{ user_id }	Each user key includes a user id based on the next_user_id and stores information related to the user, including username subkey.	Hash
Users	Contains a mapping between each User's username and user_id	Hash
followers:{ user_id }	Stores user ids for all of the users that following a particular user along with a timestamp score	Sorted set
following:{ user_id }	Stores user ids for all of the users that a particular user is following along with a timestamp score	Sorted set
next_post_id	post id counter	String
post:{ post_id }	Message, timestamp, and creating User for a single post	Hash
posts:{ user_id }	Posts from users that the User is following	List

Create a User

>>> def add_user(username):
	user_id = local_redis.incr("next_user_id")
	user_key = "User:{}".format(user_id)
	local_redis.hset(user_key, "username", username)
	local_redis.hset("Users", username, user_id)
	return user_key
>>> first_user_key = add_user("dwallace")
>>> second_user_key = add_user("bbarker")
>>> print(first_user_key)
     

Add followers to a User

>>> def add_follower(user, follower):
	follower_key = "followers:{}".format(local_redis.hget('Users', user).decode())
	local_redis.zadd(follower_key, time.time(), local_redis.hget('Users', follower))
>>> add_follower('dwallace', 'bbarker')
     

Add following

def add_following(user, following_user):
	following_key = "following:{}".format(local_redis.hget('Users', user).decode())
	local_redis.zadd(following_key, 
                         time.time(), 
                         local_redis.hget('Users', following_user))
     

Add a Post

def create_post(username, body):
	post_id = local_redis.incr("next_post_id")
	post_key = "post:{}".format(post_id)
	local_redis.hmset(post_key, {"user_id": local_redis.hget("Users", username),
				     "time": time.time(), 
                                     "body": body})
	followers = local_redis.zrange("followers:{}".format(
            local_redis.hget("Users", username).decode()),
				       0,-1)
	for follower_id in followers:
		posts_key = "posts:{}".format(follower_id.decode())
		local_redis.lpush(posts_key, post_id)
	return post_key
      

Retrieve all posts from users that a person is following

def get_my_posts(username):
	user_id = local_redis.hget("Users", username)
	posts_id = "posts:{}".format(user_id.decode())
	posts = local_redis.lrange(posts_id, 0, -1)
	for post_id in posts:
		post_key = "post:{}".format(post_id.decode())
		print("""{}:\n{}""".format(local_redis.hget(post_key, "user_id"),
					   local_redis.hget(post_key, "body")))

      

The first steps running node.js, is to download and install node.js and then install the recommended node.js client. We will also two other node modules, express and swig to build a simple website using Redis.

$ sudo apt-get install node.js
$ npm install hiredis redis
$ npm install express
$ npm install swig --save
  

Second, change directory to the node example directory and run the node.js application

$ cd introduction-to-redis/programming-redis
$ node server.js
Application Started on http://localhost:1337/
  

To see an existing Node.js project that uses Redis, checkout Amir Rajan's Todo Application at https://github.com/amirrajan/nodejs-todo.

$ git clone https://github.com/amirrajan/nodejs-todo.git
$ cd nodejs-todo
$ npm install