unsubd / post_views

Problem statement from Kutumb

post_views

Solution for a Post View counter.

1. post-server.go : HTTP server that serves the requested post.

   a. The user is identified by the jwt present in Authorization http header.

   b. A jwt can be generated by sending username and password as a HTTP POST request to /login endpoint

    Sample request {"username":"[e-mail]","password":"test"}
   

   c. send an HTTP GET request to /posts/{id} to fetch a post

   d. When a user successfully requests for a post, a post_view event is published to the analytics message queue (kafka with topic post_views)

2. analytics-page-counts-handler.go : Kafka consumer for the post_views topic

   a. When the consumer gets a message, it parses it and updates the count on the 'counts' db (cassandra with a counter table)

   b. The post count and the user who read the post are kept separately in their individual tables namely post_views and post_users. This is because cassandra restricts you to create have a mutable field in a counter table.

   c. post_users.users field is a set of users, represented by their IDs as a string d. Schema for post_views table

   column	type	primary key?	indexed?
   postId	text	true	true
   counts	counter	false	false

   e. Schema for post_users table

   column	type	primary key?	indexed?
   postId	text	true	true
   users	set<text>	false	true

3. analytics-server.go : Http server to run analytics queries

   a. HTTP GET to /analytics/posts/{id}/users will return all the users who have seen the given post

   b. HTTP GET to /analytics/users/{id}/posts will return all the posts (POST IDs) that the user has seen