Anatomy of a Couchbase App¶

J Chris Anderson demonstrated a web app somewhat similar to Snapchat, which:

uses Couchbase for asset storage and keyspace management;
doesn’t require complex queries - build your Couchbase key using predictable key patterns;
uses Couchbase to provide ordering, immutable keys and expiry;
is built with Express, React.js and PubNub.

How it works¶

The app asks the server for a message ID;
The server hands them out sequentially and atomically;
The app saves images and audio to URLs based on the message ID;
Optionally allow messages to self-destruct.

The latency sensitive path just uses key-value operations (getting documents that are referred to by other documents can be done in a reasonable timeframe using two round-trips). The messages in a room are just the messages from 0 to the current message number, so the app just does a bunch of sequential gets.

Scaling¶

Since there’s not a lot of logic on the application server (it’s effectively stateless), we can scale by adding machines and balancing load between machines.